Gradient habitat modeling of Regal fritillary and larval host

plant using a distribution modeling approach with notes on

life history attributes

Male Female

Kelsey McCullough, Gene Albanese & David A. Haukos

Introduction

Why Are

They

Important?

The Regal fritillary was once an abundant

butterfly species of the prairie biome.

Populations have declined approximately 99% in

the prairie region and it is nearly extirpated from

the eastern portion of its former range.

However, populations within northeastern Kansas

remain relatively abundant and are considered

stable.

Causes for the population decline of Regal

fritillary remain largely undetermined but the

decline of this species appears to be the result of

habitat loss and the subsequent breakdown of

metapopulation dynamics.

Regal Fritillary: Life History• Regal fritillary are univolitne

with an adult flight from June-

September.

• They mate

soon after

they emerge.

• Oviposition

is delayed

until late

August-

September.

• Females lay

several

hundred

eggs with

reports of

some

females

laying more

than 1,000

eggs.

• Females

emerge 1-2

weeks after

males.

• Oviposition behavior appears to be somewhat

haphazard, with eggs laid singly near, but not

necessarily on the violet host plants.

• Regal fritillary eggs

hatch in ~ 25 days. The

1st instar larvae

immediately consume

the chorion and enter

diapause.

• Larval

development

resumes in the

spring with the

emergence of

young violet

leaves, and is

completed by late

May - June.

• There are 6 larval

instars.

• Pupal stage of 2.5 to 4.0 weeks.

Larval Host Plant

Violets (Viola sp.) are the larval food plants for members of the genus Speyeria. While they are able to use a variety of species, Regal fritillary are associated with specific violet species in different parts of their range.

Birdfoot and Prairie violet (V. pedata, pedatifida) are thought to be the preferred larval food plants throughout the Midwestand Great Plains.

Prairie violet is a small perennial plant characteristic of native tallgrass communities within Kansas.

• Background Prairie Violet

Objectives

Provide spatially explicit estimates of the current distribution and relative abundance

patterns of Prairie violet and identify habitat features and management practices that

influence the occurrence and density of Prairie violet at the Fort Riley Military Reserve

(FRMR) and Konza Prairie Biological Station (KPBS).

Provide spatially explicit estimates of the current distribution and relative abundance

patterns of adult Regal fritillary and identify habitat features and management practices

that influence the occurrence and density of adult Regal fritillary within the FRMR and

KPBS.

Provide spatially explicit estimates of the current distribution and relative abundance

patterns of post diapause female Regal fritillary and identify habitat features and

management practices that influence the occurrence and density of post diapause female

Regal fritillary within the FRMR and KPBS.

Provide spatially explicit estimates of the current distribution and relative abundance

patterns of Regal fritillary larvae and identify habitat features and management practices

that influence the occurrence and density of late instar larvae among discrete clusters of

Prairie violet within the FRMR and KPBS.

Predicting Prairie Violet Occurrence

Methods We used Prairie violet occurrence data

collected during the 2012 REU program

at KPBS as the response variable in a

maximum entropy model.

Using GIS technologies we calculated a

suite of surface metrics.

From these surface metrics, we selected

a parsimonious set of variables for the

final distribution model.

Field Validations of Prediction Areas

Methods We randomly distributed ~ 312 violet survey

points among the 4 study areas using GIS and

then surveyed these points to validate the

predictions of the species distribution model.

10m2 plots were surveyed for ~12 min. After

the entire plot had been searched the number

of violets present were recorded.

We also randomly selected a subset of points

to re-survey to account for detection error.

27.5% of the plots surveyed had Prairie

violets present.

Larvae Surveys

Methods During violet surveys we selected ~ 5 areas to

conduct larvae surveys.

After initial surveys at each point we used violet

count data collected to predict the density of violets

within grids using variogram and interpolation

models.

Based on model results, we searched for larvae

within a subset of10m2 and 5m2 sub-plots inside

each 100m2 grid.

We searched for larvae at various times including

dusk, dawn, day and night.

The 5 larvae that we detected were found during

night surveys.

9, 9 9 ,8 9 ,7 9,6 9,5 9, 4 9, 3 9, 2 9 ,1

8, 9 8 ,8 8 ,7 8,6 8,5 8, 4 8, 3 8, 2 8 ,1

7, 9 7 ,8 7 ,7 7,6 7,5 7, 4 7, 3 7, 2 7 ,1

6, 9 6 ,8 6 ,7 6,6 6,5 6, 4 6, 3 6, 2 6 ,1

5, 9 5 ,8 5 ,7 5,6 5,5 5, 4 5, 3 5, 2 5 ,1

4, 9 4 ,8 4 ,7 4,6 4,5 4, 4 4, 3 4, 2 4 ,1

3, 9 3 ,8 3 ,7 3,6 3,5 3, 4 3, 3 3, 2 3 ,1

2, 9 2 ,8 2 ,7 2,6 2,5 2, 4 2, 3 2, 2 2 ,1

1, 9 1 ,8 1 ,7 1,6 1,5 1, 4 1, 3 1, 2 1 ,1

1 0, 9 10, 8 10, 7 10 ,6 10 ,5 10 ,4 10 ,3 1 0, 2 10, 1

9 ,10

8 ,10

7 ,10

6 ,10

5 ,10

4 ,10

3 ,10

2 ,10

1 ,10

10, 10

69 85 0 0.0 0 0 0 0 0

69 85 0 0.0 0 0 0 0 0

6 98 5 50 . 0 0 00 00

6 98 5 50 . 0 0 00 00

6 98 60 0 .0 0 0 0 0 0

6 98 60 0 .0 0 0 0 0 0

4340

550 .0

0000

0

4340

550.0

0000

0

4340

600 .0

0000

0

4340

600.0

0000

0

4340

650 .0

0000

0

4340

650.0

0000

0

4340

700 .0

0000

0

4340

700.0

0000

0

High

Low

Prairie Violet Density

RODNEY

Larvae Pupa Adult

Feed Sign

Adult Surveys

Methods Adult surveys started in early June.

Standardized transects were surveyed using

a repeated, modified pollard walk method.

Twenty six transects surveyed in 2014.

Location of transects stratified by violet

density and management regime i.e.

grazing, fire return interval, haying etc.

The coordinates and number of Regal

fritillary detected within 4 distance classes

to 30 meters from the transect and the initial

coordinates of were recorded.

Vegetation Surveys

We conducted vegetation surveys to

characterize vegetation along transects

and relate to adult abundance.

Vegetation survey points were randomly

distributed along adult survey transects.

We used a modular vegetation plot

method to quantify percent cover of

trees, shrubs, grass, forbs, ferns, bare

ground and litter.

In addition to percent cover we also

surveyed for host plants and measured

vegetation height.

We surveyed 182 vegetation plots along

the 26 adult survey transects.

Methods Vegetation Survey Map

Oviposition Surveys

Methods Oviposition surveys started in late August

and were finished in early October.

Standardized transects were surveyed using a repeated modified pollard walk method.

6 oviposition transects were surveyed in 2014.

Location of transects stratified by violet density and management regime i.e. grazing, fire return interval, haying etc.

Start/stop coordinates of followed females were recorded.

Oviposition Surveys

We followed gravid females to

record oviposition locations.

Females were recorded

depositing eggs at 27 locations.

Each location was marked with

a flag and habitat

measurements were collected.

5 eggs were collected for

further observations.

Blue violet (Violoa sororia) was

detected at 14 of the 27

locations.

Results Oviposition Map

Female Laying Eggs

Eggs & 1st Instar Larvae

Prairie Violet Distribution Modeling

Improving

our SDM

We used a similar analytical framework with the 2014 field data as we did with the pilot data to predict Prairie violet occurrence.

To improve the current Prairie violet distribution model, we are using 2014 field data to model and compare alternative distribution modeling techniques that include:

Random Forest (RF)

Boosted Regression tree (BRT)

Generalized Linear Model (GLM)

Multivariate Adaptive Regression Splines (MARS).

Better data (e.g., presence and absence data etc.)

Comparing multiple models facilitates the selection of the model that best predicts the occurrence of Prairie violets (i.e., adaptive modeling).

Maps of Predicted Prairie Violet Occurrence

within Study Areas in North Central Kansas

Preliminary Results

BRT correct classification rate

78.7%

MARS correct classification rate

73.5%

RF correct classification rate

68.4%

GLM correct classification rate

60%

Vegetation Index

Roughness

Annual Variation in

Vegetation Index

Heat Load Index

Model Performance Top Covariates

Conclusions

Progress Using GIS and distribution modeling we produced a

predictive distribution map of Prairie violet within

our study areas.

Our study identified environmental variables that

predicted the occurrence of the Regal fritillary host

plant, Prairie violet.

Validated the species distribution model with field

surveys.

Collected larvae, adult, oviposition and supporting

vegetation data.

Implemented and improving the SDM’s to compare

and select among models.

Conclusions

Coming Up We will validate the improved Prairie violet

distribution model with new surveys within FRMR

and KPBS.

We will generate a species distribution model for

Blue violet and test this model with field

validations.

We will collect a second field season of data on

adults, larvae, ovipositioning females and collect

supporting vegetation data among study sites.

These data will then be applied to occupancy and

distribution models as well as identify habitat and

management attributes that are important to

maintaining Regal fritillary populations.

ACKNOWLEDGMENTS: We gratefully acknowledge funding and

support from the Department of Defense, Konza Prairie Biological

Station, KSU Division of Biology, and the Kansas Cooperative Fish and

Wildlife Research Unit.

QUESTIONS?