COSTA RICA FOREST RESEARCH

PROGRAMME (CRF)

Carate, Osa Peninsula, Costa Rica

CRF Phase 162 Science Report 1 April 2016 – 31 June 2016

Jenna Griffiths, Pascal Lovell, Charlotte Watteyn

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CRF Phase 162

Staff Members

Jenna Griffiths (JG) Research and Operations Manager (ROM)

Pascal Lovell (PL) Principal Investigator (PI)

Charlotte Watteyn(CW) Principal Investigator (PI)

Berglind Karlsdottir (BK) Assistant Research Officer (ARO)

Alex McCaffety (AC) Assistant Research Officer (ARO)

Saule Paltanaviciute Assistant Research Officer (ARO)

Katie Buckley Assistant Research Officer (ARO)

Brooke Bierhaus Field Communications Officer (FCO)

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Contents 1. Introduction ............................................................................................ 4

1.1 Natural history of Costa Rica and its wildlife conservation ............... 4 1.2 Osa Peninsula ................................................................................... 5 1.3 Aims and Objectives of Frontier CBP ................................................ 8

2 Training ................................................................................................. 10 2.2 Briefing Sessions ............................................................................. 10 2.3 Science Lectures ............................................................................. 10 2.4 Field Training .................................................................................. 11 2.5 BTECs, CoPEs and TEFLs during phase CRF162. ............................... 11

3 Research Work Programme .................................................................. 12 3.2 Survey Areas ................................................................................... 12 3.3 Projects .......................................................................................... 13

3.3.1 Estimating the Population Density of the Four Primate Species Coexisting ............................................................................................. 13 3.3.2 Mammal track study along Rio Carate, Osa Peninsula ................. 17 3.3.3 Turtle predation study along Carate and Leona beach, Osa Peninsula. ............................................................................................. 24 3.3.4 Birds of Carate lagoon, a study on the species richness and abundance ............................................................................................ 24 3.3.5 Bird species richness and abundance in primary, secondary and degraded forest..................................................................................... 29

4 References ............................................................................................ 36

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1. Introduction

1.1 Natural history of Costa Rica and its wildlife conservation

Costa Rica, located between Nicaragua and Panama, is one of the seven Central American

countries and covers an area of 51.100 km2. It is surrounded by the Pacific on the west and the

Caribbean on the east, creating a coast line of 1103 km and 255 km respectively. Even though

this small country covers only 0.01 percent of the earth’s surface, it contains >4% of the world’s

biodiversity, including around 12,000 plant species, 1,239 butterfly species, 838 bird species,

440 reptile and amphibian species, and 232 mammal species (Sánchez-Azofeifa et al., 2002;

IUCN, 2006; World Resources Institute, 2006; National Biodiversity Institute, 2007). The high

species richness has been attributed to two main factors; its geographical location and climatic

conditions. The fact that Costa Rica is situated between North and South America means it can

serve as a species corridor between these two continents. Furthermore, it lies halfway between

the Tropic of Cancer and the equator, leading to an annual average temperature of 27 °C, with

very little fluctuations throughout the year. Therefore, the seasons in this area are defined by

precipitation, not temperature, resulting in a distinct dry and wet season. The dry season starts

around November/December and continues through April/May, after which the rainy season

begins. The southern Pacific lowlands receive a particularly high degree of average annual

rainfall (about 7,300 mm) (Baker, 2012). Although more than one-fifth of Costa Rica is protected,

further action must be taken in order to raise, or at least sustain the current level of biodiversity

(World Resources Institute, 2006).

Costa Rica is one of the world’s leading countries in environmental sustainability and

conservation (Fagan et al., 2013), however, this has not always been the case. Like many other

countries throughout the world, Costa Rica has been the site of extensive deforestation over the

past few centuries. Up until the 1960s, activities such as logging and hunting seriously

threatened the biodiversity in this region, resulting in over half of the country’s forests being cut

down and many species being driven to the verge of extinction (Henderson, 2002). The poaching

of turtles for the fatty calipee and collection of turtle eggs for example, has severely depleted

populations of endangered black turtles (Chelonia mydas) and vulnerable olive ridley turtles

(Lepidochelys olivacea) that use Costa Rica’s coastlines as nesting sites. Similarly, the hunting of

Costa Rica’s wild cat species, peccaries and tapirs for their meat, skins and other body parts, has

significantly reduced wild populations. Since the 1960s, some of these issues have been

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controlled through the implementation of several reforestation programs, legislation, education

and the creation of protected areas, now representing almost 27% of the country’s surface area

(The World Bank Group, 2015). Costa Rican law currently protects 166 species from being

hunted, captured and traded, yet illegal hunting still occurs, including in protected areas (Baker,

2012). Deforestation and habitat fragmentation outside of the country’s protected areas and

national parks is still a significant problem due to expanding human populations and related

increases in economic pressure. Additionally, the projected impacts of climate change are also

likely to have significant adverse effects on Costa Rican biodiversity (Baker, 2012). Due to the

high levels of biodiversity and multiple threats placed on Costa Rica it is important to conduct

research to determine the health of the ecosystem and its species. Massive deforestation and

the resulting biodiversity crisis have already increased awareness and interest in conservation

of tropical habitats worldwide (Wilson, 1992), but the real practice requires a basic

understanding of the native fauna and flora; and since tropical forests are not single,

homogeneous, biotic formations (Gentry, 1990), the biodiversity of these areas must be

understood on a local, as well as regional, level.

1.2 Osa Peninsula

The Osa Peninsula is located in the southwest of Costa Rica and covers an area of 1093 km²

(Henderson, 2002). The peninsula contains the last remnants of tropical broadleaved evergreen

lowland rainforest on the Central American Pacific slope (Kappelle et al. 2002) and has a very

high species richness of about fifty percent of Costa Rica’s biodiversity. Furthermore, this area

inhabits several endemic species such as the Cherrie’s Tanager (Ramphocelus costaricensis), the

Red-backed squirrel monkey (Saimiri oerstedii)) and the Golfo Dulce poison dart frog

(Phyllobates vittatus). Since these and more species are only found in this area, it makes the Osa

Peninsula the ideal location for conservation research (Larsen & Toft 2010).

Three main forest types can be found in the Osa Peninsula; Tropical Wet, Premontane Wet and

Tropical Moist forest, with elevations ranging between 200 and 760 m (Santchez-Azofeifa et al.,

2002). The variation in topography leads to a highly variable climate, with an average annual

rainfall of 5500 mm, a mean temperature of around 27 °C and humidity levels almost never

dropping below 90% (Cleveland et al, 2010). There are about 12,000 people living in the Osa

Peninsula, mainly settled in small and scattered villages. The most important sources of income

in this region are agriculture (rice, bananas, beans and corn), livestock (cattle), gold mining,

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logging and, more recently, the expanding eco-tourism industry (Carrillo et al., 2000).The human

population is increasing at a rate of 2.6% annually, which is incredibly high compared to 1.3% in

the rest of the country and 1.14% globally (Sánchez-Azofeifa et al., 2001). As a result of the

growing popularity of ecotourism, there has been a rise in the number of hospitality business

along the road, from Puerto Jimenez to Carate, since the 1990s (Minca and Linda, 2002). This

has caused growing concern for the sustainability of the region’s environmental resource

demands (Sánchez-Azofeifa et al., 2001).

The Frontier’s Costa Rica Forest Research (CRF) programme began in July 2009 in collaboration

with the local non-governmental organisation, Osa Conservation, based at the Piro site (N

08°23.826, W 083°20.564) in the southeast of the Osa Peninsula. In October 2015, Frontier

moved to Carate, located in the southwest of the Osa Peninsula. The site is a prime location for

carrying out both forest and shoreline surveys as there is relatively easy access to both the

primary and secondary forest, as well as pristine beach habitat. The long term objectives of the

project are to provide information on the dispersal and diversity of faunal communities in the

Golfo Dulce Forest Reserve, with the aim of increasing protections and connectivity in the area,

whilst also investigating the effects of climate change, deforestation and other anthropogenic

impacts on the terrestrial communities of Costa. There are five core faunal study groups within

CRF; primates, sea turtles, wild cats and other mammals, herpetofauna and bird

Figure 1. Map of the Osa Peninsula, showing Carate, our area of study http://www.vivacostarica.com/costa-rica-

maps/costa-rica-maps-southern-pacific.html.

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1.3 Aims and Objectives of Frontier CBP

Under the umbrella of the research program, the specific aims and objectives of Frontier CRF

are:

1. To estimate the population density, distribution and feeding preferences of the four

primate species present in Carate, Osa Peninsula, Costa Rica; and compare these among

the different habitat types present in this area.

2. To assess mammal species richness and abundance along Rio Carate by searching for

natural tracks in and near the riverbed.

3. To assess nest success and turtle nest predation by conducting morning and night turtle

patrols along two beaches, Playa Carate and Playa Leona.

4. To determine bird species richness and abundance in and around the lagoon of

pejeperrito in Carate; and to see how changes in environmental variables affect the

presence of these species.

5. To compare the bird species richness and abundance between primary, secondary and

degraded forests, by performing point counts along the different trails, focusing on 44

forest bird species selected on several criteria, such as endemism, IUCN status,

ecological function and migratory features.

6. *To gather information about the amphibian and reptile species richness in the primary,

secondary and degraded forests of Carate, Osa Peninsula, Costa Rica.

*The points in italic are the studies that are still in their initial phases. We are currently working

on developing the methods to carry out these studies.

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2 Training

The volunteer Research Assistants (RAs) and newly appointed staff members receive a number of

briefing sessions on arrival (Table 1), followed by regular science lectures and field training (Table 2)

throughout their deployments. The CRF research program also supports candidates completing the

BTEC Advanced Certificate, Advanced Diploma in Tropical Habitat Conservation, the Certificate of

Personal Effectiveness (CoPE) and the Teach English as a Foreign or second Language (TEFL) (Table 4).

2.2 Briefing Sessions

All the people newly arriving to CRF get an introduction towards the aims of the research program, the

methodologies used and the research output of the individual projects. Furthermore, they get an

update on the achievements of CRF through a general Science presentation; this is an introduction to

the Frontier Costa Rica Forest Research Program in Carate. Additionally, all volunteers and staff are

given a health, safety and medical briefing, of which they are tested on before participating in any field

activity. Volunteers undertaking any kind of the previous mentioned qualification courses are given an

introductory briefing before they begin the assessments.

Table 1. Briefing sessions conducted during Phase CRF162

Briefing Session Presenter

Introduction to the Frontier Costa Rica Forest Research Programme JG, CW

Health and Safety Briefing and Test CW, BK, AC, SP

Medical Briefing and Test CW, BK, AC, SP

Introduction to the BTEC, CoPE & TEFL Qualifications JG, CW

Introduction to Surveying and Monitoring ALL

Camp Life and Duties JG, CW

2.3 Science Lectures

A broad program of science lectures is offered at CRF, providing information and training the different

aspects of research going on in our study area. Lectures are presented using PowerPoint and give a

better understanding about the biology and ecology of the studied species. Furthermore, they give an

insight in the methods and data analysis used by CRF and considerations made when planning research

projects.

Lectures are scheduled with the following objectives:

To allow every volunteer and member of staff to attend each presentation at least once during

deployment, regardless of length of stay.

To meet the time requirements for BTEC assessments.

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Name BTEC Title and Type Mentor

Bea Tropical Habitat Conservation – Advanced Certificate BB, SP

Lucia Tropical Habitat Conservation – Advanced Certificate AR

Marianne Tropical Habitat Conservation – Advanced Certificate BK

Eleanor Tropical Habitat Conservation – Advanced Diploma AC, KB

To avoid conflict with other activities, maximizing attendance

To provide detailed training on specific software and applications used in conservation, such as

GPS.

Attendance of lectures is compulsory.

Table 2. Science lectures delivered during Phase CRF162.

Science Lecture Presenter

Primates JW, AC

Terrestrial birds ALL

Lagoon birds BK

Turtle patrol survey JG

Mammal tracks and GPS workshop JG

Amphibians and Reptiles BK

Climate change ALL

2.4 Field Training

All volunteers and newly appointed staff members receive field training. Training is hands-on and

provides an opportunity to become familiar with the field equipment used during surveys. These

sessions are held before starting every survey, to inform volunteers and new staff members about the

way the survey is carried out and to assure accurate data collection. Both in the field and on camp site,

various identification books are present to teach how to identify flora and fauna species.

2.5 BTECs, CoPEs and TEFLs during phase CRF162.

Frontier offers volunteer Research Assistants an opportunity to gain internationally recognised

qualifications based around teamwork, survey techniques, environmental conservation and effective

communication of results. The BTEC in Tropical Habitat Conservation can be done in a four week

program (Advanced Certificate) or a ten week program (Advanced Diploma). Table 4 gives an overview

of the BTECs carried out during this phase.

Table 3. BTECs, CoPEs and TEFLs during phase CRF 162.

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3 Research Work Programme

3.2 Survey Areas

All the fieldwork is carried out in Carate, located in the southwest of the Osa Peninsula. The research

in this area began in November 2015. The landscape is heterogeneous, composed of lowland moist

primary, secondary and coastal forest, and disturbed forest. Dominant tree species include; Ficus

insipida, Ceiba pentandra, Attalea butyracea, Carapa guianensis, Castilla tunu, Spondias mombin,

Hyeronima alchorneoides, Chimarrhis latifolia, Fruta dorada, Caryocar costaricense, Ocotea insularis,

Pouteria torta, and Inga allenii. Mean annual rainfall and temperature for the area is 5,000-6,000 mm

and 26-28 °C respectively; the dry season extends from the end of December until March. Different

trails have been selected, including the different types of habitat and with different degrees of usage

and disturbance (table 4). These trails are used as survey transects for the eight different projects.

Most of the trails are narrow and machete-cut. The exact habitat types present on the trails is not yet

known, for example, it is highly possible that Luna ridge contains a mix of primary and secondary

forest. In order to assess this in more depth GIS work is being undertaken and in-depth habitat studies

are required, perhaps with the help of drones to get more knowledge about all the different habitat

types present in Carate and surroundings.

Table 4. Current trails used for the research carried out in Carate S coordinates of the start and the end of the trail, as well as the length (km).

Trail Name (code) Transect Length (km)

GPS Coordinates START trail

GPS Coordinates END trail

Disturbed forest Attalea Loop (with some secondary forest patches)

1 km 08º26'11.14 N 83º26'16.99 W

08º26'29.60 N 83º29'02.37 W

Road 1.8 km 08º26'28.37 N 83º26'25.73 W

08º26'28.11 N 83º27'16.33 W

Secondary forest Shady Lane 2.5km 08º44'44.59 N

83º27'49.54 W 08º26'48.19 N 83º28'52.97 W

Beach Trail (mix of coastal and secondary forest) 2 km 08º26'36.69 N 83º44'63.16 W

08º26'50.30 N 83º29'02.37 W

Leona Loop 2km 08º26'56.09 N 83º29'04.37 W

08º26'56.39 N 83º29'05.16 W

Gallery forest Rio Carate 2.5 km 08º44'22.75 N

83º46'31.56 W 08º27'37.30 N 83º27'48.69 W

Primary forest Leona Ridge 4 km 08º26'48.19 N

83º28'52.97 W 08º26'54.51 N 83º29'05.16 W

Luna Ridge 9 km 08º26'29.63 N

83º27'16.62 W

08º26'28.54 N 83º26'56.86 W

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Turtle patrols take place on two beaches; Playa Carate and Playa Leona. River Rio Carate passes

through the survey areas, bordering the National park of Corcovado, and has an important function in

providing water and food for animals when they move out of the park.

3.3 Projects

3.3.1 Estimating the Population Density of the Four Primate Species Coexisting

Introduction

Throughout Costa Rica, four different primate species can be found; the Central American squirrel

monkey (Saimiri oerstedii), the mantled howler monkey (Alouatta palliata), the geoffroy’s spider

monkey (Ateles geoffroyi) and the white-faced capuchin (Cebus capucinus). The Osa Peninsula is the

only part of Costa Rica where these four new world primate species occur together, making this place

a very interesting area for study (Carrillo et al., 2000). Primates are predominantly frugivorous,

therefore, they have an important ecosystem function as seed dispersers, making them vital for

maintaining the plant diversity within the forest (Julliot, 1997; Garber et al., 2006). Generally, primate

species are highly sensitive to land conversion for agricultural purposes and development, clear

cutting, selective logging, hunting and the pet trade (Cropp and Boinski, 2000). In Costa Rica, primates

are mainly threatened by increased rates and amounts of forest loss and fragmentation, and

infrastructural changes for the country's booming tourism industry. In Panama, they have fared even

worse since deforestation has been extensive and unregulated (Boinski & Sirot 1997; Boinski et al.

1998). The development of agribusinesses for oil palm and banana plantations is a serious component

of habitat destruction and fragmentation. Logging roads, clearings for telephone and electric power

lines, or other practices leading to forest fragmentation restrict populations to smaller forest areas,

decreasing their ability to find food during times of the year when food abundance is lowest (e.g. dry

season) and leading to declines of genetic diversity, which in turn affects the population health and

stability (Boinski et al. 1998).

Since October 2015 Frontier CRF has been surveying the presence of the four primate species in Carate.

The overall research aim is to gain more knowledge about the distribution of the four primate species

in this area of the Golfo Dulce Reserve. By comparing the richness and abundance of primate species

between the different habitat types, we can gain more information regarding management and policy

decisions on a local level. Until now, density estimates are lacking for the Central American squirrel

monkey and the white-faced capuchin, which makes them key to survey, however, focus is also placed

on the red listed spider and howler monkeys.

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The Central American squirrel monkey (Saimiri oerstedii) is one of the five species of squirrel monkeys.

Their status on the IUCN list is Vulnerable, with decreasing populations (IUCN, 2008). The main threats

are habitat loss due to logging and agriculture. They inhabit the lowland rainforests of Pacific Costa

Rica towards Western Panama. They are an arboreal and diurnal species, depending on a diet of

insects, leaves, fruits, barks, flowers and nectar, and foraging in the low and middle levels of primary

and secondary Forests. Group sizes range from 20 to 75 individuals that are travelling between 2.5 and

4.2 km per day (IUCN, 2008). The white-headed capuchin (Cebus capucinus), also known as the white-

faced or white-throated capuchin, has a very important ecological function within the forest ecosystem

by dispersing pollen. They are Least Concern on the IUCN list but their main threats include tree logging

and clear-cutting because these activities drastically reduce suitable habitats. Other threats include

the capturing for the pet trade and hunting for their meat. Like the squirrel monkeys, the capuchins

are diurnal and arboreal species with a diet of mainly fruits and insects. They range from Honduras all

the way down to Ecuador and are highly adaptive species, meaning they can occupy various habitats,

but usually occur in tropical evergreen and dry deciduous forests. Their group size ranges from 4-40

individuals, with a mean average of 16 and they travel on average 2 km a day (IUCN, 2008). The Golden

mantled howler monkey (Alouatta palliata) is found in Costa Rica, Nicaragua, Panama and Guatemala,

mostly in the older areas of evergreen primary forest as well as secondary and semi- deciduous

forest. They have an important function as seed dispersers and germinators and their dung is an

important food source for several dung beetle species. Their status on the IUCN list is Least concern

(IUCN, 2008). They are diurnal, arboreal species with a diet that mainly consists of leaves, giving them

low amounts of energy which makes them rest for most of the day. Their main threats are forest

destruction and fragmentation. The group size ranges from 10-20 individuals, but can reach up to 40

individuals. The males are characterized by a very obvious white scrotum when they reach sexual

maturity and have an enlarge hyoid bone which allows them to create a loud howling noise, usually

displayed at dawn and dusk (IUCN, 2008). The Geoffroy’s spider monkey (Ateles geoffroyi) is native to

Costa Rica and Panama and is currently Endangered with a decreasing population (IUCN, 2008). They

are diurnal and arboreal species, mainly inhabiting the upper layers of the forest, and have a diet of

fruits, leaves and sometimes insects, seeds, barks and flowers. Their threats are habitat loss and

hunting for their meat and the pet trade. The group size ranges from 20-40 individuals that are living in

a fission-fusion society, meaning that they split into subgroups during the day and congregate again

during the night (IUCN, 2008).

Material and Methods Data was collected by walking six different trails (Beach trail, Road, Attalea loop, Luna ridge, Leona

loop, Shady lane) and conducting total counts of all the primates encountered. The surveys started

between 05.30 and 06.00 am, to cover peak primate activity and thus increasing detection

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probability. A minimum of three observers walked at a constant speed of 2 km/h, including regular

stops every 100m as recommended by Peres (1999). The six trails were divided into three main

habitat types; primary (Luna ridge, Leona loop), secondary (Beach trail, Shady lane) and degraded

(Road, Attalea loop) forests. Each trail was walked in one way, and not more than once a week. The

surveys were done in fair weather because of reduced detection probability in adverse weather

conditions. As phase two included the start of the reason, there were some problems with cancelling

surveys because of adverse weather conditions. When encountering a monkey troop, an observation

time of maximum 30 minutes was set. This provided enough time to assure a reliable count of all the

individuals without disturbing them for too much time (Pruetz & Leasor 2003). All individuals seen at

the same time and exhibiting the same general behaviour (i.e., resting, moving or foraging) were

considered to be part of the same group (Chapman et al., 1995). Where possible, secondary data on

group composition (i.e. gender and age; adult, juvenile, infant) was also recorded. Furthermore, the

behaviour (i.e. resting, moving or foraging) upon encounter, the duration of observation, the

perpendicular distance from the trail to the geometric centre of the group at first sighting, height of

the group in the tree and direction of travelling was noted. This study was non-invasive and according

to the legal requirements of Costa Rica (Costa Rican Government Decree 31514-MINAE). Any kind

of abnormal or aggressive behaviour towards the observers by individual primates was responded to

by moving on as quickly as possible.

Results

A comparison was made between the abundance of the different primate species of the six different

trail types (Luna ridge, Leona ridge, Shady lane, Beach trail, Attalea loop, Road) (figure 2), that are

divided in three main habitat types (primary, secondary and degraded forest). A Kruskal-Wallis test

was carried out, since there are more than 2 groups to compare and the data didn’t fulfill the

requirements to carry out a parametrical test. The p-value is lower than 0.05, meaning that there is a

significant difference between the groups (here: trails) in mean amount of individuals per primate

species. On average, the lowest amount of primates was found on the trails with primary forest,

whereas the highest amount was encountered on the trails with secondary and degraded forest.

Squirrel and capuchin monkeys were not encountered in Leona and Luna ridge, which are the trails

containing primary forest. They were only present on the other trails, which are the ones containing

secondary and degraded forest. The other two primate species were found on all the trails, but more

on the trails that hold secondary and degraded forest.

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Figure 2: Mean abundance of individuals per primate species encountered on the six different trails.

Discussion

During this phase, focus was placed on the abundance of the four primate species among the six

different trails. The results so far showed the opposite of what was expected. More primates were

seen in the secondary and disturbed forests than in the primary forests. One reason for this could be

that they use the disturbed forest patches as a corridor to move in between secondary and primary

forest patches. Since primate groups cannot be followed during the whole day, it is difficult to know

where exactly they are foraging so the data collected thus far cannot be relied upon. Therefore, it

would be preferable to focus on the overall distribution of the primates in Carate and their trophic

preferences.

A general study on their distribution will be established in the next phase and their richness and

abundance among the different types of habitat will be compared. More research is needed to find

suitable methods, for example, the use of line transects, and a laser range finder to make better

estimates about the distances of the primate groups from the observation point on the trail, etc.

This will involve a more in-depth literature study during the next phase in which we hope to

implement the new methods.

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3.3.2 Mammal track study along Rio Carate, Osa Peninsula

Introduction

In general, protected areas are the backbone of conservation and are supposed to safeguard the

species inside the area. However, many protected areas don’t function in the way they should (e.g.

Caro & Scholte, 2007; Russel & Cuthill, 2009; Craigie et al., 2010). Effective protection to maintain

healthy species richness and abundance can vary with the location and size of the area. Furthermore,

abiotic and biotic as well as indirect and direct human activities occurring close to the borders of the

reserve, such as firewood collection, cattle grazing, bush fires, fishing and hunting, are affecting all the

organisms living in or crossing the periphery of the reserve (Laurance, 2010). With increasing human

disturbance, mammals often move to the central parts of protected areas while areas closer to the

park boundaries may be less attractive due to the negative effects of human activities along the edges.

Despite the fact that these so-called edge effects can have big consequences regarding conservation

issues (e.g. Primack, 2010), this topic has received little attention. Most of the studies have been

focusing on large carnivore species (e.g. Revilla et al., 2001; Slotow & Hunter, 2010), showing that their

large individual home ranges are extending the boundaries of the decreasing reserve areas, leading to

a movement outside the reserves via buffer zones, however, the threats outside the reserves block

these species from moving out of the reserve. Instead, they often have to move back towards the

centre, leading to population declines due to habitat and food competition. Despite protective

legislation, these kind of human-wildlife conflicts are common throughout Central and South America

(Zimmermann et al. 2005), as natural habitats are still being converted for agricultural purposes and

resource extraction, and poaching activities are still present along the reserve borders (Cavalcanti &

Gese 2009).

Estimating the distribution and abundance of mammals is not that easy. Especially in the case of the

Osa Peninsula, where big mammals are extending their home ranges from Corcovado National Park

towards other areas within the Osa Peninsula. This makes it even more vital to conserve and manage

these areas and the biological corridors that connect them. Information on the distribution is also vital

for the introduction of education and awareness initiatives, with the aim of preventing human-wildlife

conflict that threatens mammal populations and livelihoods across the species range (Zimmermann et

al. 2005). The aim of this study is to estimate the mammal species richness and abundance along the

river Rio Carate, which is located at the border of Corcovado National Park, the Osa Peninsula, Costa

Rica. Corcovado National Park compromises primary lowland rainforests, and serves as an important

haven for various animals and plant species. However, for many mammal species, the area of the park

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is not sufficient to maintain healthy populations. By using tracking techniques, we can gain knowledge

about the mammal species present in and along the border of the park, and it will give us an idea of

which mammals are moving in and out of the park. This is especially important for feline species, since

their broad distribution ranges obligate them to move in between different protected areas in order

to not override their maximum carrying capacities.

Material & Methods

Tracking mammals by following footprints is probably the oldest known method of identifying

mammal’s presence in an area (Bider, 1968). Track surveys are efficient and usually low in cost, but are

dependent on suitable field conditions and trained observers (Burnham et al, 1980; Smallwood &

Fitzhugh, 1995). Track searches were performed along the river Rio Carate, Carate, Osa Peninsula,

Costa Rica; starting at the river estuary, and going two kilometres upstream. The surveys consisted of

volunteers walking and looking for tracks in and around the riverbed. Surveys started at 7:00 am to

prevent tracks from being washed away. More than 200 mammal species are currently present in the

different forest types of Costa Rica, with this study focusing on 20 mammal species. Table 6 gives an

overview of the 19 selected mammal species. All species are found in the lowland rainforests of the Osa

Peninsula (Cavalcanti & Gese, 2009). Among the focal species’ distribution range, only the Baird’s

tapir is listed as Endangered. Many other mammal species are listed as globally Vulnerable or Near

threatened (IUCN, 2014). However, in Costa Rica, the six feline species, Neotropical river otter and

Paca are considered to be Endangered (Cavalcanti & Gese, 2009).

All mammal tracks were recorded and identified by measuring its widest point and the vertical distance

from the toes to the palm pad and by using mammal track sheets (Adapted and modified of Sanchez,

1981). The GPS position of the track was noted down as well as the direction of movement. This gave

information on the movement of individuals within a certain area. If a track of the same species was

found within 100 m from the previous track, it was not recorded and was assumed to be the same

individual. Due to the very dry substrate, which is a mix of sand and rubble, a considerable level of skill

was necessary to accurately detect and identify the tracks.

Finally, the program Estimate S was used to estimate the mammal species diversity. With this

program, we are able to estimate the Simpson’s diversity Index, which is essentially the probability of

two randomly chosen individuals (tracks) being from different species. Furthermore, an estimate of

the evenness was made, which showed how evenly distributed the species were.

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Table 6. Overview of the 20 selected mammal species (IUCN, 2014)

Common species name Latin species name IUCN status Costa Rica status

Baird’s tapir Tapirus bairdii Endangered Endangered

Collared peccary Peccari tajacu Least concern Least concern

White-lipped peccary Tayassu peccary Vulnerable Endangered

Red brocket deer Mazama Americana Data deficient Data deficient

Tayra Eira Barbara Least concern Least concern

Neotropical river otter Lontra longicaudis Data deficient Endangered

Striped hog-nosed skunk Conepatus semistriatus Least concern Least concern

Common opossum Dedelphis marsupialis Least concern Least concern

Water opossum Chironectes minimus Least concern Least concern

Northern tamandua Tamandua Mexicana Least concern Least concern

White-nosed coati Nasua narica Least concern Least concern

Crab-eating raccoon Procyon cancrivorus Least concern Least concern

Central American agouti Dasyprocta punctate Least concern Least concern

Paca Agouti paca Least concern Least conern

Nine-banded armadillo Dasypus novemcinctus Least concern Least concern

Puma Puma concolor Least concern Endangered

Ocelot Leopardus pardalis Least concern Endangered

Jaguarondi Puma yagouaroundi Least concern Endangered

Margay Leopardus wiedii Near threatened Endangered

Jaguar Panther onca Near threatened Endangered

Figure 2. Standard measurements taken; A- Track widest point and B- vertical distance from the toes to the palm pad.

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Results

During this second phase of the mammal track project, 16 different species were seen over 15 surveys,

of which 2 were unidentified (1 unidentified cat spp, 1 unidentified mammal species). The 14

identified species were: agouti, armadillo, Baird’s tapir, red brocket deer, collared peccary, common

opossum, crab-eating racoon, margay, Neotropical river otter, ocelot, tayra, water opossum, white-

lipped peccary, and white- nosed coati. 104 different individuals were seen over the 15 surveys. The

mean species count per sample (or in our case survey) was 6.5; meaning that on average, six different

species were seen each survey. The amount of tracks for each mammal species is given in figure 4.

Most of the tracks are from the Neotropical river otter, followed by the ocelot, Baird’s tapir, crab-

eating raccoon and white-nosed coati.

1.4

1.2

1

0.8

0.6

0.4

0.2

0

Figure 4. Graph representing the amount of tracks found per mammal species over the 15 surveys.

The cumulative number of species encountered (y) levels off with the cumulative number of samples

(surveys) carried out over time (x) (figure 5). However, after carrying out a rarefaction, the curve does

not level off much towards the end, suggesting that the maximum number of species in the area have

not been recorded.

we have not been able to record the maximum number of species present in the area.

MEA

N E

NC

OU

NTE

R O

VER

SU

RV

EYS

MAMMAL SPECIES

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Sanple Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total

Species Count 7 6 4 3 6 3 4 5 1 6 2 3 3 2 0 16

Cumulative Spcies Count

7 10 10 11 13 13 13 13 13 15 15 15 16 16 16 16

Abundance 9 9 5 8 5 5 4 16 1 10 2 5 2 4 4 89

CU

MU

LATI

VE

SPEC

IES

NU

MB

ER

Rarefaction: A statistical interpolation method of rarefying or thinning a reference sample by drawing

random subsets of individuals (or samples) in order to standardize the comparison of biological diversity on the

basis of a common number of individuals or samples.

Species accumulation curve: A curve of rising biodiversity in which the x-axis is the number of sampling units

(individuals or samples) from an assemblage and the y-axis is the observed species richness. The species

accumulation curve rises monotonically to an asymptotic maximum

number of species.

18

16

14

12

10

8

6

4

2

0

0 2 4 6 8 10 12 14 16

CUMULATIVE SURVEY NUMBER

Figure 5. The species accumulation and rarefaction curve.

Table 7. An overview of the species count, cumulative species count, abundance and cumulative sample number. The species

count gives the amount of species found in each sample (survey). The cumulative species count adds the amount of species

found in sample x to the amount of species found in sample x-1. The abundance gives the amount of individuals over all the

species found in each sample. The cumulative sample number gives the amount of samples (surveys) carried out during the

period.

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Log

Cu

mu

lati

ve S

pec

ies

Nu

mb

er

The extrapolated species accumulation curve (figure 6), gave the equation for an estimation of how

many surveys would be needed to observe the maximum amount of species present in the area. Table

7 shows the amount of species we would have throughout the surveys. So far, 15 surveys have been

completed, revealing the tracks of 16 species. Based on the formula, around 19 different species’

tracks should have been seen, which shows that the equation gives a good estimate of reality.

1.4

1.2

1

y = 0.4495x + 0.7838

0.8

0.6

0.4

0.2

0

0 0.2 0.4 0.6 0.8 1 1.2

Log Cumulative Sample Number

Figure 6. The extrapolated species accumulation curve with an equation that gives the relationship between the species

richness and the number of samples (surveys).

Sample Number

Cumulative Species Number

Log Sample Number

Log Cumulative

Species Count

1 7 0 0.84509804

2 10 0.301029996 1

3 10 0.477121255 1

4 11 0.602059991 1.041392685

5 13 0.698970004 1.113943352

6 13 0.77815125 1.113943352

7 13 0.84509804 1.113943352

8 13 0.903089987 1.113943352

9 13 0.954242509 1.113943352

10 15 1 1.176091259

11 15 1.041392685 1.176091259

12 15 1.079181246 1.176091259

13 16 1.113943352 1.204119983

14 16 1.146128036 1.204119983

15 16 1.176091259 1.204119983

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Furthermore, the output of Estimate S gave an estimate of the species diversity, similarly to the Simpson’s

diversity index. The Simpson’s mean (D) was 8.21, and from this the Simpson’s mean index (1-D) was

calculated with the formula 1-D = 1-(1/D) = 0.878197. Since this is close to 1, it means that there was a high

mammal species richness over all of the surveys. Using the Simpson’s diversity index, evenness (E) was

calculated with the formula E = (1/D)/S, with S being the amount of samples (surveys). The result was

0.631538, which is closer to 1, meaning that Rio Carate is characterized by a quite an evenly distributed

abundance of species.

Discussion

From the results so far we can see that there are 16 mammal species present and active around Rio

Carate. 15 surveys have been carried out, and a higher sample effort is needed to determine the true

value of the number of species found here. The extrapolation curve (Figure 6) is starting to level off at the

end, meaning that the number of species detected in this study is quite close to the number of species

present in this area (that can be detected with this methodology).

Most of the tracks were identified as Neotropical river otter, which can be mainly explained by the fact that

the surveys were carried out along the river Rio Carate. It is still interesting to see that even though it is

dry season, there are still quite a few otters present in the area. During dry seasons, mammals tend to

move to other places to look for more favourable habitats. They have to look for water and food

resources that they are not finding in the areas they used to live during the wet season. Quite a lot of

ocelot tracks were observed, as well as Baird’s tapir, crab-eating raccoon and white-nosed coati. The

presence of feline species tracks, such as the ocelot, shows that wild cats are moving in and out of

Corcovado National Park, however, more data and analysis is needed to figure out how abundant they are

and to which areas they are moving to and from.

The data during phase two was collected towards the start dry season, probably affecting the encounter

probability as it is thought that mammals move deeper into the centre of a protected area (in this case

Corcovado National Park), looking for food and water resources. In general, the composition of mammal

communities depends on the forest’s ability to support the requirements of the mammals present in the

area. Modification of habitats, such as temporal or spatial changes, may generate boundaries for species

due to the newly created patchiness in the landscape, and this has effects on the structure and dynamics

of all biological communities (Cadenasso et al., 2003). Surveys carried out over the whole year, will make it

interesting to see if there is a difference in the amount of mammal species and abundance we see during

the wet and dry seasons.

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During the following phase, some changes to the methodology should be made. Instead of only using

natural mammal tracks, track boxes of a previous BTEC student will be used and placed higher up the river

since observational walks have shown that there are more tracks present higher up. Data will continue to

be taken from natural tracks, but the trail will be extended higher up the river as so far only a length of

about 2km is covered. Furthermore, many mammals are shy and elusive creatures, and their adaptation to

live in the undergrowth or canopy, or their nocturnal lifestyle makes detection difficult. Over the years,

wildlife biologists have used various tracking techniques to assess mammal populations. The most

common method is to detect the tracks left in fine soil or sand (Olifiers et al. 2011), which is what we did

during this phase, however, the addition of camera traps will allow for much more efficient detection. This

method is especially efficient for inventories of cryptic animals as well as for population studies of species

for which individuals can be individually recognized by marks (Karanth, 1995; Carbone, 2001). Camera-

trapping is an important non-invasive tool for assessing patterns of mammal abundance and richness

throughout space and time, and their link with activity patterns, habitat use and reproductive information,

which are key elements for wildlife conservation research. Track surveys are efficient and usually involve

low costs, but depend on suitable field conditions and trained personnel (Burnham et al., 1980; Smallwood

and Fitzhugh, 1995). Camera-trapping on the other hand is more costly at the beginning, but is not so

dependent on the environment to be sampled, constant assistance or experienced field staff (Rappole

et al., 1985). Once camera trapping has been included in the methodology, the data from it can be

combined with the data from track surveys.

3.3.3 Turtle predation study along Carate and Leona beach, Osa Peninsula.

As the high season for the turtles that nest in this region only starts in August, turtle patrols are only

carried out from July onwards (during the next phase), and therefore the study has not been included in

this report.

3.3.4 Birds of Carate lagoon, a study on the species richness and abundance

Introduction

Coastal areas are typically characterised by a high human population density and thus activity, causing a

high pressure on the associated ecosystems, such as lagoons. Increasing human activity results in

environmental deterioration and disturbs biogeochemical processes that are going on in the lagoons

(Seitzing et al., 2005; Halpern et al., 2008; Qu & Kroeze, 2010). Due to ideal temperatures and

precipitation patterns, tropical coastal areas are very productive zones, and are therefore highly affected

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by anthropogenic nutrient loading compared to similar habitats at higher latitudes (Yule et al., 2010;

Smith et al., 2012).

Coastal lagoons are shallow waterbodies, spatially separated from the ocean by sandbars and barrier

islands or temporarily separated during certain times of the year (Johnston, 2000). They are highly

productive ecosystems, providing several ecosystem services valuable for society, including fisheries,

storm protection, tourism, etc. (Gönenc & Wolflin, 2005; Anthony et al., 2009). Although, little changes in

water quality can have big effects on the functioning of the lagoon, and all its associated living organisms.

The degree to which a lagoon is sensitive towards changes in water quality mainly depends on the lagoon

type, referring to its exchange rate with the ocean and its size and on the faunal and floral communities

present in and around the lagoon (Johnston, 2000). Due to the little amount of information available about

the sensitivity of lagoons towards changes in water quality, there is a need to examine which environmental

parameters affect the health of the lagoon in general, with focus on the bird communities. There are a

couple of quality parameters that are expected to have a big influence on the functioning of lagoons, such

nutrient enrichment, turbidity, toxic contamination and organic enrichment (Johnston, 2000). Especially

with changing climate, these parameters can vary, affecting the physical structure, ecological

characteristics and social values associated with lagoons. Expected shifts in physical and ecological

features range from changes in flushing regimes, freshwater inputs and water chemistry, to inundation

and habitat loss (Anthony et al., 2009). Gathering more information about coastal lagoons, especially in

the context of climate change, is critical. In this study, the bird species richness associated with a tropical

lagoon, situated in Carate, Osa Peninsula, Costa Rica, is studied; as well as their response upon changes in

environmental parameters. In addition, evidence from the few lagoon-specific studies undertaken,

suggests that once impacted (particularly by nutrient enrichment) lagoons may recover slower from

impacts due to changes in water quality. This highlights the need to identify water quality impacts within

lagoons as early as possible and suggests the need for a precautionary approach to interpreting and acting

on information that may indicate an impact (Johnston, 2000).

This study seeks to examine the health of the lagoon Pejeperro in Carate. Bird species richness and

abundance will be examined in order to understand how the lagoon is functioning. Furthermore,

information will be gathered about different environmental parameters, their change over time and the

effect on the bird diversity.

Material and methods

The study is carried out at the coastal lagoon Pejeperro, located on Carate beach, Carate, Osa Peninsula,

Costa Rica. During dry season (December-may), the lagoon is separated from the Pacific ocean, changing

the internal characteristics (e.g. salinity, nutrient concentration, turbidity). Heavy rains allow the lagoon to

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connect again with the ocean. The lagoon is surrounded by lowland rainforest and gets disturbed by the

activities of local fisherman and tourists staying at the surrounding eco-lodges. A group, consisting of a

minimum of three and maximum five observers, carry out the survey at two different spots close to the

lagoon. A minimum of three persons are necessary to fulfill the health and safety requirements of the

Frontier Costa Rica Project (see earlier), and a maximum of five persons allows us to minimise the

disturbance on the foraging behaviour of the birds during the survey. The spots were chosen in such a way

that we are close enough to see and identify the birds without disturbing them too much. Once arrived at

the survey point, all the different bird species present in the lagoon, on the sandbanks as well as in the

vegetation surrounding the lagoon were noted down. Not included in the study were bird species of the

lowland rainforest from right behind the lagoon since these bird species were more likely to be part of the

forest ecosystem. Birds were identified with binoculars and bird identification books (Garrigues, 2014). If

they were unidentifiable, pictures were taken and then identified back on camp.

Results

During the second phase (April – June 2016), 32 different lagoon bird species were identified in and

around the lagoon of Carate. Table 8 gives an overview of the identified lagoon bird species, grouped

by family.

Table 8: Overview of the identified lagoon bird species, grouped by family.

Herons, Sandpipers, Guls, Plovers, Ibises, Spoonbils Jacanas Rails, Other Egrets, Allies Terns, Lapwings (Threskiornithidae) (Jacanidae) Crakes, lagoon- Bitterns (Scolopacidae) Skimmers (Charadriidae) Gallinules dependent

(Ardeidae) (Laridae) (Rallidae) birds

Bare- throated

tiger heron

Sandpiper spp.

Black tern Black-billed plover

Roseate spoonbill Northern jacana

Purple gallinule

Baltimore oriole

Great egret

Solitary sandpiper

Least tern Plover spp. White ibis Black vulture

Great blue heron

Snowy plover Blue-back grosbeak

Green heron

Southern lapwing

Blue-winged teal

Little blue heron

Cherries tanager

Reddish egret

Crested caracara

Snowy egret

Great kiskadee

Tri- coloured

tiger heron

Great-tailed grackle

Yellow- crowned

night heron

Scarlet macaw

Smooth-billed ani

White- collared

seedeater

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The Ardeidae family is well represented in and around the lagoon (table 8). The families containing the

little birds, such as the sandpipers, terns and plovers, are less represented. Besides the typical lagoon

bird species, we also saw a number of species not exclusively found in the lagoon (scarlet macaws,

black vultures etc). Figure 6 below shows the mean amount of individuals seen per species during the

first two phases of the year.

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MEA

N A

MO

UN

T O

F IN

DIV

IDU

ALS

12

10

8

6

4

2

0

Figure 6: Mean amount of individuals per species seen during phase 1 and 2. Discussion

This is the first time that a lagoon bird study has been carried out on this project. During the first

weeks, observers had to get to know the birds and needed more time to identify them. Now, those

conducting the surveys are more skilled and are able to spot and identify the different bird species

more easily.

From Figure 6 we can see that the species that were detected in the highest abundance were the

northern jacana, white ibis, and the bare-throated tiger heron respectively. However, these species

are very easily identified and may have skewed their detection probability to their favour.

It is hoped that, during the next phase, the effects of disturbance on the species richness and

abundance of the lagoon birds can be investigated. By comparing surveys with (human) disturbance to

surveys without (human) disturbance, we can see if kayaks, fisherman, etc. have a negative influence

on the bird diversity in the lagoon. It could be noted that observers conducting these studies also

disturb the birds present in and around the lagoon. However, since there is a high level of species

richness, it can be said that this presence has a very low effect on their behaviour or no effect at all.

Another idea is to include different environmental parameters into the study. Since it is known that

salinity, temperature, pH, depth, etc. influence the functioning of lagoon ecosystems, it is important

to know have they vary over time and if this influences the presence of bird species in and around the

lagoon. In order to carry out these extra measurements, MINAE need to be contacted and the

standard protocol for water quality monitoring needs to be followed.

Finally, the use of kayaks during the next phase of the study would be necessary in order to survey

the whole lagoon, as currently only a small area of the lagoon can be observed from the shore,

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making data collection difficult. This will require going into the water before sunrise, finding a fixed

spot in the lagoon and waiting until birds arrive. In this way, we don’t disturb them since we are not

moving and are stationary in the kayak.

3.3.5 Bird species richness and abundance in primary, secondary and degraded forest

Introduction

The highly heterogeneous environments of Costa Rica give rise to many species-rich communities,

particularly those within the bird families (Herzog, Kessler & Cahill, 2002). Costa Rica hosts

approximately 850 bird species, of which 160 species are endemic (Henderson, 2010). This high bird

species richness means that Costa Rica has a relatively long history of studies focusing on bird

community structure (e.g., Young et al, 1998; Blake & Loiselle, 2001; Sigel et al, 2006) and demography

(e.g., Ruiz-Gutiérrez et al, 2008; Young et al, 2008; Woltmann & Sherry, 2011). Birds provide various

important ecological functions, such as seed dispersion and pollination, and can therefore help in the

maintenance of plant communities, and even contribute towards the reforestation of fragmented

habitats (Pejchar et al., 2008). However, the majority of bird studies have been carried out in pristine

habitats with very little attention given to degraded or fragmented areas (Wilson, Collister & Wilson,

2011). Furthermore, partly due to its remoteness, little is known about the bird communities of the

Osa Peninsula despite its extraordinary species diversity and high levels of endemism (Wilson, Collister

& Wilson, 2011).

Home to approximately 375 species of birds (or 420 species according to Garrigues, 2007), including

many migratory birds and 18 endemic species (Sanchez-Azofeifa et al, 2002), the Osa Peninsula

comprises one of the largest remaining tracts of intact lowland rainforest in Mesoamerica (Barrantes

et al, 1999). This provides important habitat for a myriad of bird species. While 39% of the region is

under the protection of Corcovado National Park, in recent decades significant development,

deforestation and forest fragmentation has occurred outside of the reserve (Sanchez-Azofeifa et al,

2002).

Deforestation and fragmentation is considered the primary threat to birds in the Osa Peninsula (Osa

Conservation, 2016). Due to a human population growth rate of 2.6% (Sánchez-Azofeifa et al, 2001)

and increases in ecotourism, large areas of forest have been cleared to make space for agricultural

practices and the hospitality industry (Minca & Linda, 2002). Studies have found that in the period

between 1979 and 1997 the percentage of forested area in the Osa decreased from 97% to 89%

(Sanchez-Azofeifa et al, 2002). Furthermore, Sanchez-Azofeifa et al (2002) found that as of 1997, the

majority of the remaining forest outside of Corcovado National Park has been altered, with only 44%

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of the region representing mature forest. Today, the tropical forest exists as a patchwork of various

size, age and connectivity within a human-dominated landscape (Wilson, Collister & Wilson, 2002).

Particular bird groups, such as understory insectivores (Canaday, 1996; Sekercioglu et al, 2002; Sigel et

al, 2006), can be very sensitive to such changes, whilst others are able to utilise degraded and

fragmented habitats (Wilson, Collister & Wilson, 2002). Development is likely to continue in the Osa

Peninsula and thus it is of the upmost importance to understand how birds, outside of Corcovado

National Park, are being affected by these changes.

In addition to deforestation and fragmentation the birds of the Osa Peninsula are up against another

threat: climate change. This threat is not unique to the region, however, changes in temperature,

precipitation and greater climatic extremes are likely to have significant impacts on the avifauna. Due

to the fact that birds are endothermic, increased temperatures may cause greater energy use for

thermoregulation (Wormworth & Mallon, 2006). Additionally, temperature changes can indirectly

affect the birds reproduction, timing of breeding and migration (Wormworth & Mallon, 2006). For

example, shifts in temperatures cause birds to shift the timing of seasonal events such as egg laying or

migration (Wormworth & Mallon, 2006). This causes birds to be out of synchrony with other species,

particularly plants and insects, which are necessary for their survival (Wormworth & Mallon, 2006).

Such changes may significantly impact species’ reproductive success, which could ultimately result in

the collapse of breeding populations in the long-run (Wormworth & Mallon, 2006). Precipitation

changes are also expected to negatively affect bird populations. Studies have shown that periods of

low or zero rainfall are correlated with lower bird populations due to reduced food availability

(Wormworth & Mallon, 2006). Furthermore, it is believed that climate change is likely to increase

extreme weather events such as drought or flooding (Wormworth & Mallon, 2006). Extreme conditions

can alter important habitats and reduce the survival rates of both young and adult birds. Moreover,

drought or floods in critical stopover areas along bird migration routes can impair migratory birds’

ability to reach their final destination (Wormworth & Mallon, 2006). Altogether, the effects of climate

change and birds responses to it will vary from species to species, thus it is critical that the different

species of the Osa Peninsula are monitored in order to determine how they are being affected.

Overall, the high species diversity and endemism of the avifauna in the Osa Peninsula coupled with the

threats of deforestation, fragmentation and climate change, highlights the need to better understand

and monitor the birds in the region. Due to the lack of scientific studies on birds in the Osa Peninsula,

Frontier aims to determine the species richness and abundance of birds in Carate in relation to their

habitat and disturbance, since bird distribution and species richness is often explained by habitat type

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and environmental characteristics. Therefore, owing to their sensitivity towards environmental changes,

birds are good indicators of habitat health (Wilme & Goodman, 2003). Monitoring trends in bird

diversity may help to identify species at risk of population decline or even extinction due tohuman-

induced environmental changes, such as habitat fragmentation and loss, climate change,

pollution and pet trade (Pejchar et al., 2008).

As such, the main objective is to compare the species richness and abundance between disturbed,

secondary and primary forest habitats through point count surveys, whereby the bird species are

recognized by sound and sight. In addition, Frontier aims to support the goals of the National Parks

Service in the United States of America and MINAE by monitoring migratory birds species that inhabit

both North America and migrate to Costa Rica during winter periods. Finally, due to the sensitivity of

birds to climate change, Frontier aims to monitor the bird species diversity and abundance in

conjunction with climatic changes over the long term.

Material and Methods

This study focuses on 44 bird species, and the species are selected based on the following criteria;

endemic species, data deficient/poorly studied species, specialist species, migratory species, species

under threat (according to the IUCN) and species that perform a high ecological function. Worldwide,

the most important places for habitat-based conservation of birds are the Endemic Bird Areas (EBAs).

Most of the bird species are widespread and can inhabit large ranges of habitats. Some however are

said to be endemic since they are restricted to specific areas due to food and habitat requirements.

The landscapes where these species occur are high priority for broad-scale ecosystem conservation.

EBA’s are found around the world, but most of them are located in the tropics and subtropics,

especially the tropical lowland forest and moist montane forest. Geographically, EBA’s are often

islands or mountain ranges (Birdlife International, 2008). The poorly studied species are species with

very few or deficient data available about their status, distribution, abundance, etc., which makes them

highly prioritized species to study. Specialist species are occurring in certain habitats because of

specialist habitat or food resource needs. If their habitat disappears, it is very likely that the species

disappears will disappears too. Regarding the migratory species, we are working together with the

American National Park of North America and Canada. The bird species that are migrating from north

to south during northern hemisphere winters are being studied since little information is available

about these species when they are moving towards the south. Finally, the bird species with important

ecological functions are also our focus on species, since they have important functions within the

ecosystem they live. For example, woodpeckers make holes in trees that are habitats for other species

such as bats, beetles, etc.

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Table 9: Overview of the selected 44 bird species on study.

Bird species common name Bird species Latin name Selected criteria

Fiery-billed Aracari Pteroglossus frantzii Endemic species to Pacific Costa Rica

and Western Panama

Chestnut-mandibled Toucan Ramphastos swainsonii Vulnerable

Black-bellied Wren Pheugopedius fasciatoventris Endemic species to Pacific Costa Rica

and Western Panama

Riverside Wren Cantorchilus semibadius Endemic species to Pacific Costa Rica

and Western Panama; Data deficient

Cherries Tanager Ramphocelus costaricensis Endemic species to Pacific Costa Rica

and Western Panama; Data deficient

Blue-crowned Manakin Lepidothrix coronata Endemic species to Pacific Costa Rica

and Western Panama

Red-capped Manakin Ceratopipra mentalis

Orange-collared Manakin Manacus aurantiacus Endemic species to Pacific Costa Rica

and Western Panama

Pale-billed Woodpecker Campephilus guatemalensis Specialist species; Ecologically

important function

Golden-naped Woodpecker Melanerpes chrysauchen Endemic species to Pacific Costa Rica

and Western Panama

Long-tailed Woodcreeper Deconychura longicauda Near threatened

Bright-rumped Atilla Attila spadiceus Disturbance indicator

Rufous Mourner Rhytipterna holerythra

Rufous Piha Lipaugus unirufus Specialist species

Tawny-Crowned Greenlet Hylophilus ochraceiceps Specialist species; Data deficient

Scarlet Macaw Ara macao Data deficient

Turquoise Cotinga Cotinga ridgwayi Endemic species to Pacific Costa Rica

and Western Panama; Vulnerable

Yellow Warbler Setophaga petechia Migratory species

Golden-winged Warbler Vermivora chrysoptera Migratory species

Blue-winged Warbler Vermivora cyanoptera Migratory species

Black-hooded Antshrike Thamnophilus bridgesi Endemic species to Pacific Costa Rica

and Western Panama; No data

Black-cheeked Ant-tanager Habia atrimaxillaris Endemic species to the Osa Peninsula;

Endangered

Bicoloured Ant-bird Gymnopithys leucaspis

Dot-winged Antwren Microrhopias quixensis Specialist species

Ruddy-tailed Flycatcher Terenotriccus erythrurus Specialist species

Sulphur-rumped Flycatcher Myiobius sulphureipygius

Yellow-billed Cotinga Carpodectes antoniae Endemic to Costa Rica; Endangered

Baltimore Oriole Icterus galbula Migratory species

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Rufous-tailed Jacamar Galbula ruficauda Disturbance indicator

Wood Thrush Hylocichla mustelina Near threatened; Migratory species

Smooth-billed Ani Crotophaga ani Disturbance indicator

Common Potoo Nyctibius griseus Poor data; Vulnerable

Great Tinamou Tinamus major Poor data; Climate change indicator

Great Curassow Crax rubra Vulnerable; Climate change indicator

Spectacled Owl Pulsatrix perspicillata Ecologically important function

Crested Guan Penelope purpurascens Poor data

Marbled wood Quail Odontophorus gujanensis Near Threatened

Spot-crowned Euphonia Euphonia imitans Endemic species to Pacific Costa Rica

and Western Panama; Specialist

species

Green-shrike Vireo Vireolanius pulchellus Data deficient

Mealy Parrot Amazona farinosa Ecologically important function

White-crowned Parrot Pionus senilis Poor data; Ecologically important

function

Brown-hooded Parrot Pyrilia haematotis Poor data; Specialist species

Black-Throated Trogon Trogon rufus Poor data

Baird’s Trogan Trogon bairdii Endemic species to Costa Rica; Near

Threatened

Using point counts, estimates of the bird species richness and abundance can be made. Point counts

are a widely used method to assess the distribution patterns and relative abundance of birds in tropical

habitats (Miller et al., 1998; Sánchez-Azofeifa et al., 2001; Henderson, 2010). A point count refers to a

count carried out by someone that is standing at a fixed place, from which the target species (birds)

are counted by sight and call, and this for a fixed period of time (Bibby et al., 2000; Gibbons & Gregory,

2006; Hartley & Greene, 2012). The methodology is quite straightforward and observers can easily

gather the required data by walking a trail and stop at different points to record all the present bird

species by sound and sight. It must be said that, due to the high level of tree density within a tropical

forest, as well as the very high species diversity in this region, there is quite a high level of experience

necessary to detect and identify birds accurate. The point counts are carried out along all the different

trails; Luna ridge, Leona ridge, Shady lane, Rio Carate, Attalea loop, road. During each survey, three

point counts are carried out, separated 250 m from each other and started at 100 m from the forest

edge. Since we work with a distance radius of 0 – 30 m (1), 30 – 100 m (2) and >100 m (3), it is important

to stick with the 250 m in between the point counts to avoid an overlap of counts. Furthermore, it is

important to take into account the effort efficiency of the observers. This is why not more than three

point counts were carried out during every survey since there is a drop in focus over time, making it

important to find a compromise between collection effort and precision / accuracy (Verner,

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1985). Before starting the recording period of ten minutes, there is a two minute settling period to

allow the birds coming back after our disturbance from walking towards the point counts. The point

counts are permanent points, which are permanently chosen locations within a site and clearly marked

with colourful tape flags (Huff et al., 2000). All the birds that are seen and heard within the different

radius are noted down (sight: S; sound: H), as well as the flying-over and flying-thrus birds are recorded

in a separate list as respectively FO and FT.

3 2 1

Figure 8: Graphic view of the distance radius used during the point counts.

The analysis will consist of calculating biodiversity indices of the data collected for each of the different

rainforest types. Firstly, the Species Richness index will be calculated; this is simply the number of

different species detected in each habitat, and the number of unique species will also be observed.

Secondly, the Shannon Diversity index will be calculated to allow a comparison of biodiversity between

the different habitats and taking into account the abundance of each species found (the Shannon Index

discriminates against species where very few were detected, giving a better overall view on the

diversity of an area). Lastly, the Simpson’s Diversity index will be calculated, which is given as a scale

between zero and one. The closer the Simpson’s Diversity index is to zero, the lower the diversity (an

environment with a Simpson’s Diversity index of 1 will have equal numbers of all the species detected;

and an environment with an index closer to 0 will have a large abundance of one or more species

compared to the rest).

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Results Table 10 below shows a summary of the different indices used to calculate diversity. Table 10: Summary table of the Species Richness, Unique Species, Shannon Diversity index, and the Simpson's

Diversity index.

FOREST TYPE SPECIES RICHNESS

UNIQUE SPECIES

SHANNON INDEX

SIMPSONS INDEX

SAMPLE EFFORT

PRIMARY 17 2 2.34 0.88 11

SECONDARY 22 5 2.03 0.79 16

DISTURBED 12 1 2.18 0.84 12

GALLERY 11 0 1.48 0.67 8

From the above table, we can see that the secondary forest has the highest species richness (22) and

unique species (5), however the primary forest has the highest biodiversity indices (Shannon=2.34;

Simpson’s=0.88). The gallery forest has the lowest species richness (11), unique species (0), and both

Shannon and Simpson’s indices (1.48 and 0.67 respectively).

Discussion

From Table 10 in the results section we can see that the secondary forest has higher species richness (22)

and unique species (5) than the primary forest (17 and 2 respectively). However, after taking into account

the different diversity indices it can be concluded that although the species richness is higher in secondary

forest, it includes a lot of species that were only detected once (40% of the species detected in the

secondary forest were detected only once, compared to 12% in the primary forest). Therefore it can be

conclude that the primary forest has the highest levels of biodiversity, and this result is echoed in many

other comparative studies of biodiversity. The higher level of biodiversity in primary forest can be

attributed to lower levels of habitat degradation and fragmentation, which is known to affect bird species

worldwide, as well as the presence of a higher diversity of flora which may support specialist species

vulnerable to deforestation. The gallery forest has the lowest levels of biodiversity, with the lowest values

for both the Shannon (1.48) and Simpson’s Diversity (0.67) indices. This low value for the Simpson’s

Diversity in the gallery forest can be attributed to the fact that 50% of the individuals detected were scarlet

macaws, therefore there is a higher likelihood that two individual observations chosen at random will be

the same species. The disturbed habitat also has higher biodiversity indices than the secondary forest,

which may also be due to the fact that 41% of the individuals detected in secondary forest were scarlet

macaws, compared with 30% in the disturbed forest.

The secondary forest detected the most unique species (5), including the endangered Black-cheeked ant

tanager (detected once), and the near-threatened Marbled wood quail and Wood thrush (also both

detected only once). That there were more unique species (including species threatened with extinction)

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detected in the secondary forest despite there being lower levels of biodiversity when compared with

primary forest can be attributed to the fact that there was a higher sample effort there (16 compared to

11), as well as detection being simpler in more degraded habitat (it is harder to detect certain species in

denser, primary forest).

This study is still very much in its infancy, with staff members as well as volunteers still in the process of

learning bird calls and recognizing them by sound and sight. Furthermore, bird sound recording

equipment will be purchased in order to record the bird calls in the field and identify them back on

camp by using the online catalogued bird calls. This will ensure a more reliable dataset by double

checking bird call recognizing skills in the field with the recordings. Furthermore, it will be possible to

observe the accuracy of the observers before surveys are carried out.

4 References

Barrantes, G., Q. Jimenez, J. Lobo, T. Maldonado, M. Quesada, & R. Quesada. 1999. Manejo Forestal y

Realidad Nacional en la Peninsula de Osa. INBio, San Jose, Costa Rica

Blake, J. G., & B. A. Loiselle. 2001. Bird assemblages in second-growth and old-growth forests, Costa

Rica: Perspectives from mist-nets and point counts. The Auk. 118: 304–

326.

Canaday, C. 1996. Loss of insectivorous birds along a gradient of human impact in

Amazonia. Biological Conservation. 77: 63–77.

Herzog, S.K., Kessler, M., & Cahill, T.M. 2002. Estimating species richness of tropical bird

communities from rapid assessment data. The Auk. 119 (3): 749-769.

Minca, C. & Linda, M. 2002. Ecotourism on the Edge: the case of Corcovado National

Park,

Costa Rica. In: Font, X. & Tribe, J. editors. Forest tourism and recreation: case studies in

environmental management. Oxon: CABI Publishing, UK. 103-127.

Osa Conservation. 2016. Our work: Birds. Available at:

http://osaconservation.org/projects/wildlife/birds/ [16 March 2016].

CRF162

37

Ruiz-Gutiérrez, V., T. A. Gavin, & A. A. Dhondt. 2008. Habitat fragmentation lowers survival of a tropical

forest bird. Ecological Applications. 18: 838–846.

Sánchez-Azofeifa, G. A., R. C. Harriss, & D. L. Skole. 2001. Deforestation in Costa

Rica: a quantitative analysis using remote sensing imagery. Biotropica. 33: 378–384.

Sanchez-Azofeifa, G., Rivard, B., Calvo, J. & Moorthy, I. 2002. Dynamics of Tropical Deforestation

Around National Parks: Remote Sensing of Forest Change on the Osa Peninsula of Costa Rica. 2002.

Mountain Research and Development. 22(4): 352-358.

Sekercioglu, C. H., P. R. Ehrlich, G. C. Daily, D. Aygen, D. Goehring, & R. F. Sandi. 2002. Disappearance of insectivorous birds from tropical forest fragments. Proceedings of the National Academy of Sciences of the United States of America. 99: 263–267. Sigel, B. J., T. W. Sherry, & B. E. Young. 2006. Avian community responses to lowland tropical rainforest

isolation: 40 years of change at La Selva Biological Station, Costa Rica. Conserv. Biol. 20: 111–121.

Wilson, S., Collister, D. & Wilson A. 2011. Community composition and annual survival of lowland

tropical forest birds on the Osa Peninsula, Costa Rica. Ornitologia Neotropical. 22:421-436.

Woltmann, S., & T. W. Sherry. 2011. High apparent annual survival and stable territory dynamics of

Chestnut-backed Antbird (Myrmeciza exsul) in a large Costa Rican rain forest preserve. The Wilson

Journal of Ornithology. 123: 15–23.

Wormworth, J. & Mallon, K. 2006. Bird Species and Climate Change: The Global Status Report version 1.0. London: Climate Risk Pty Limited. Young, B. E., D. Derosier, & G. V. N. Powell. 1998. Diversity and conservation of understory birds in the

Tilarán Mountains, Costa Rica. The Auk. 115: 998–1016.

Young, B. E., T. W. Sherry, B. J. Sigel, & S. Woltmann. 2008. Nesting success of Costa Rican lowland rain forest birds in response to edge and isolation effects. Biotropica. 40: 615–622.