BIOLOGY AND CONSERVATION OF THE NILE CROCODILE (Crocodylus niloticus)BY

YUSUFF, HAMMED OLALEKAN

MATRIC NO: 149077007

UNIVERSITY OF LAGOS

SCHOOL OF POST GRADUATE STUDIES

FACULTY OF SCIENCE

DEPARTMENT OF ZOOLOGY

OUTLINE

Introduction Taxonomy Distribution Habitat Adaptation Feeding& Reproduction Conservation status Threats Human- Crocodile Conflicts Reasons for conservation Case study Conclusion Recommendation

INTRODUCTIONCrocodylus is derived from the Greek “krokodeilos’’ which means (kroko = pebble; deilos = worm) referring to the appearance of crocodile, niloticus means "of the Nile" (Nile River, Africa)

Nile crocodile (Crocodylus niloticus) is an African crocodile, largest in africa and the second largest extant reptile in the world, after the saltwater crocodile (Crocodylus porosus).

Primarily nocturnal. In daylight, basks in the sun and cools off in the water when necessary (Fergusson, 2007).

Nile crocodiles are very social reptiles and sometimes hunt cooperatively.

The males are territorial, patrolling and are larger than females.

INTRODUCTION contd.Body Weight: 225 - 500 kg

Body Length: 2-3.3 m (6.6 -10.8 ft); Maximum Length snout to tip of tail:5 m (16.4 ft)

Sexual Maturity: 12 -19 yrs in wild.

Longevity: long lived; survive 50-80 years in the wild.

Dentition: 5 pre-maxillary; 13-14 maxillary; 14-15 mandibularTotal no. of teeth = 64-68

Source: Nile crocodile fact sheet, 2014

COMMON NAMES

English: Nile crocodile

Swahili: Mamba

Yoruba: Ooni

Igbo: Agu iyi

Hausa: Kada

TAXONOMY

Kingdom:AnimaliaPhylum: ChordataClass: ReptiliaOrder: CrocolydiaFamily: CrocodylidaeGenus: CrocodylusSpecies: Crocodylus niloticus - Nile CrocodileLaurenti, 1768

Order CrocodyliaFamily Alligatoridae Family Crocodylidae

Alligator mississippiensis (American alligator) Alligator sinensis (Chinese alligator) Caiman crocodilus (caiman): C. crocodilus

crocodilus, C. c. fuscus, C. c. apaporiensis,C. c. chiapasius

Caiman latirostris (broad-snouted caiman) Caiman yacare (yacaré) Melanosuchus niger (black caiman) Paleosuchus palpebrosus (dwarf caiman) Paleosuchus trigonatus (smooth-fronted caiman)

Family Gavialidae Gavialis gangeticus (gharial)

Source: Adapted from King and Burke, 1989

Subfamily Crocodylinae Crocodylus acutus (American crocodile) Crocodylus cataphractus (slender-snouted

crocodile) Crocodylus intermedius (Orinoco

crocodile) Crocodylus johnsoni (Australian

freshwater crocodile) Crocodylus mindorensis (Philippine

crocodile) Crocodylus moreletii (Morelet's crocodile)

Crocodylus novaeguineae (New Guinea Crocodile)

Crocodylus palustris (mugger) Crocodylus porosus (saltwater crocodile) Crocodylus rhombifer (Cuban crocodile) Crocodylus siamensis (Siamese crocodile) Osteolaemus tetraspis (dwarf crocodile) Subfamily Tomistominae Tomistoma schlegelii (tomistoma)

Crocodylus niloticus (Nile crocodile)

Plate 1: Crocodylus niloticusSource: Fergusson, 2007

DISTRIBUTION

Primarily found in Africa, though native to Madagascar.

In Africa, widespread distribution south of the Sahara

Absent from the southern tip of Africa.

Figure 1: Distribution of Crocodylus niloticus.Source: Fergusson, 2007

HABITAT

Wide habitat preferences, reflecting their success and distribution

Inhabit mostly in coastal lagoons, rivers, estuaries, lakes, waterholes and wetlands.

The dry stream beds, river banks and sandy shores of the wetlands provide preferred nesting sites where eggs are deposited during laying season (Fergusson, 2009).

ADAPTATIONNile crocodile has over 60 teeth; if any fall out during attacks on its prey, a new one replaces it.

The muscles that close a crocodile's jaws generates enormous power, yet the muscles that open the jaws have little strength.

The eyes, nose and ears are high up on the top of the skull, so that the crocodile can be almost completely submerged, yet still hear, see and breathe.

While submerged, a protective membrane closes over a crocodile's eyes - like swimming goggles.

Interacts through sounds. They produce more than six different kinds of vocal sounds.

ADAPTATION contd.Crocodiles have a very good sense of smell with large olfactory lobes in the brain.

Are cold-blooded and rely on the temperature of the sun and water to warm up.

Nile crocodiles do not normally chase their prey - their typical hunting strategy is one of surprise, lunging at prey, and they are able to use the tail and powerful hind legs to spring out of the water.

Crocodiles only eat about fifty full meals a year and can go for long periods without eating; nesting females generally fast.

The female Nile crocodile is an attentive parent, guarding its nest of sixty eggs for the entire incubation period of ninety days and the hatched young for six weeks.

FEEDINGJuveniles feeds on small aquatic invertebrates and insects, soon move onto larger vertebrates (fish, amphibians and reptiles).

Adults, however, can potentially take a wide range of large vertebrates, including antelope, impala, bushbucks, buffalo, young hippos, and even lions.

Fish and smaller vertebrates often form the greatest part of their diet,

Nile crocodiles are apex predators throughout its range, have no natural predator.

Figure 2: Food web of the Nile CrocodileSource: Fergusson, 2009

REPRODUCTIONFemales are sexually mature once they reach 2.2-2.5 metres of length or 10-12 years old, while the males are mature at 3.2 meters at 16 years old.

Males attract females by bellowing, slapping their snouts in the water, blowing water out of their noses.

Once a female has been attracted, the pair warble and rub the undersides of their jaws together.

REPRODUCTION contd.The female then digs a hole a few metres from the bank and up to 500 mm (20 in) deep, and lays between 25 and 80 eggs.

Females remain near the nest at all times.

Incubation time averages 80 to 90 days (ranges from 70 to 100 days), after which females open the nest and carry the juveniles to the water.

High percentage of nests are raided by a variety of animals, from hyenas and monitor lizards to humans.

Plate 2: A close up on a female Nile crocodile laying and burying her eggsSource: Fergusson, 2009

Plate 3: A baby hatchling right after it breaks out of its shellSource: Fergusson, 2009

CONSERVATION STATUSThe IUCN Red List assesses the Nile crocodile as “Lower risk/ Least Concern(LR/lc)’’

The species may be threatened in some parts of the range; (IUCN, 2009)

The CITES lists the Nile crocodile under Appendix I (threatened with extinction) in most of its range;Appendix II (not threatened, but trade must be controlled) in the remainder.

THREATS

General habitat loss due to pressure on resources including water, fish, sand and wetlands ( Nathaniel et al., 2010)

Direct conflict with people, uncontrolled killing in response to attacks on humans ( Nathaniel et al., 2010).

Indirect anthropogenic effects (e.g pollutants, poor water quality and dam-building coincided to cause the deaths.

Uncontrolled hunting for skin for artisanal trade in leather goods (Ottley et al. 2008).

HUMAN- CROCODILE CONFLICTCrocodilian species throughout the world are highly valued for their skin.

Many crocodiles are hunted illegally and their eggs are taken to supply crocodile farms (Aust et al. 2009; McGregor 2005; Ottley et al. 2008).

Table 1: Reported global trade in crocodilian skins 1999-2008

SPECIES 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008A.Mississi 239,944 249,155 343,116 237,840 341,734 368,409 356,393 421,220 262,133 230,464ppiensisC. acutus 0 0 100 630 830 227 204 120 404 1,371C. johnsoni 45 10 0 2 0 0 65 0 0 0C. moreletii 2 1,228 2,430 1,591 997 549 855 158 11 724

C.novae- 22,191 23,233 30,634 30,749 27,308 39,796 32,002 38,645 28,663 28,217guineaeC. porosus 15,971 25,791 28,223 24,278 26,564 30,728 37,441 34,152 45,215 53,888C. rhombifer 0 0 0 0 0 2 0 0 0 0C. siamensis 5,459 2,417 4,422 3,580 10,982 20,930 31,517 47,972 54,331 63,471

SUBTOTAL 416,951 449,145 559,682 458,640 556,968 601,138 578,451 708,574 545,046 547,430

Source: Adapted from John, 2010

C. niloticus 133,339 147,311 150,757 159,970 148,553 140,497 151,491 166,307 154,289 169,295

Plate 4: Nile crocodile skinSource: Ijeomah and Efenakpo, 2011.

Plate 5: A big Crocodile killed near a village on Africa's Niger River.Source: Brett, 2012

Plate 6: Crocodile hunters removing the skin of crocodilesSource: John, 2010

Plate 7: Leather products from crocodile skinSource: John, 2010

CROCODILE- HUMAN CONFLICTAll crocodilians are capable of harming humans.

Of the 24 species of crocodilian, only ten have been reported to carry out unprovoked attacks on humans.

Of these species, attacks by the saltwater crocodile (Crocodylus porosus), Nile crocodile (C. niloticus) and American alligator (Alligator mississippiensis) are the most widely known (Fergusson 2004; Caldicott et al. 2005; Langley 2005).

Plate 8: Human activities such as fishing potentially bring local people into conflict with C. niloticusSource: Richard Fergusson,2009

Plate 9: Injury caused by C. niloticusSource: Richard Fergusson,2009

VALUES OF NILE CROCODILE- REASONS FOR CONSERVATION

Economic values: Skin trade, Crocodile farming, Ecotourism

Ecological values : Apex-predator, help balance the ecosystem

Cultural values : Aesthetic : Recreational

: Scientific : SpiritualIntrinsic values

CASE STUDY 1 Ijeomah and Efenakpo (2011) conducted a study on the assessment of nile crocodile utilization in selected communities of rivers state, Nigeria

The study areas are Choba, Aluu and Emohua and Abonema of Rivers state.

Data for the study were obtained through pre-tested structured questionnaires, in-depth interviews and field observations.

The first set of questionnaire was administered to all crocodile consumers in the four selected communities, and also to all fishermen/hunters who had ever caught a crocodile.

CASE STUDY 1 contd.The second set of questionnaire was administered to owners (management) of crocodile farms.

Data obtained from the study were analyzed using descriptive statistic in form of counts of frequency, Bar chart and Pie chart.

In each community number of crocodile consumed in 2010 per respondent was highest (8) in both Emohua and Aluu communities.

The results show that most respondents (96.0%) considered crocodile meat desirable, about 77.0% of respondents do not make other use of crocodile but utilized it for consumption and the sub-adults (34.0%) are the mostly preferred size.

About 69.0% of respondents were aware of where crocodiles are sold though only 41.0% know the sellers.

CASE STUDY 2Sven and Alison (2012)Estimated demographics of the Nile crocodile(Crocodylus niloticus Laurenti) in the panhandle region of the Okavango Delta, Botswana

This study was undertaken in 300 km of permanent channels within the northern Okavango system, known as the ‘panhandle’ region, in Botswana.

A continuous Capture-Mark-Recapture programme was conducted from January 2002 to December 2006.

Crocodiles were located at night along predetermined non-overlapping transects using a boat and spotlight and captured by hand or noose.

A global positioning system position was recorded at the site of capture, water and air temperatures were recorded at intervals throughout each survey period.

CASE STUDY 2 contdThe lengths of all crocodiles encountered, but not captured, between June 2004 and October 2006 were estimated to determine size class distribution.

Data were separated into northern and southern panhandle datasets.

A total of 1717 individuals were captured (January 2002–December 2006) ranging in size from 136 to 2780 mm SVL.

Overall, 148 (8.6%) hatchlings, 1018 (59.3%) young juveniles, 311 (18.1%) juveniles, 177 (10.3%) sub-adults and 63 (3.7%) adults were captured.

A total of 224 crocodiles were recaptured once, 44 twice, seven were recaptured three times and one was recaptured five times.

CONCLUSIONCrocodilians are the closest surviving relatives of the great dinosaurs.

Importance of Nile crocodile in the ecosystem cannot be overemphasized.

High mortality rate of the juveniles and uncontrolled hunting of adult could lead to local extinction

RECOMMENDATIONPublic awareness campaign on the importance of this specie.

Government policies should be geared towards ensuring the conservation of this animal.

More research work need to be done.

Integration of local people in the conservation process.

The Federal and State Government, Non-Governmental Organization and Conservation bodies should encourage inhabitants of communities through remuneration, training to embark on crocodile farming and captive breeding.

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