THE EFFECT OF ELEVATION ON BIRD

MIGRATION

Michaeline Fraser3/25/2011

Ms. DonoghueMorning Intern

Mentor & Site Site: Patuxent Wildlife Research

Center With the Bird Phenology Program (BPP) Building 308, Center Road, Beltsville MD Purpose: At BPP, I do a variety of things

including sorting, scanning and refile-ing bird migration cards

All cards are from the 1880’s-1970’s Mentor: Jessica Zelt

She is the Program Coordinator of BPP.

Introduction The study conducted, researched bird arrival dates and whether elevation patterns affected their flight was studied in the states of New jersey, Maryland, Delaware, Pennsylvania and Virginia Birds Studied include Wilsonia citrina, (Hooded

Warbler) Setophaga ruticillla (Amerian Redstart), Dendroica petechia (Yellow Warbler) and Dendroica fusca. (Blackburnian Warbler) Later on other variables such as Latitude and Year were

added This topic was selected because at BPP an abundance

of bird migration cards are available and Ms. Jessica Zelt suggested these species because they are neo-tropical migrants; traveling from southern and Central America to breed in Northeastern America.

Introduction (con.)

A birds behavior is heavily dependent on the state and condition of the earth. Bird’s are very responsive to any slight fluctuations, changes or differences in the environment because those are their cues as to when to start, stop and travel during migration. Studying how birds have been affected by

elevation will provide insight on how/whether the earth has or has not been affected over time.

PhotosExample of

Bird Migration card

Few of the cabinets that store migration cards

Me holding a bird, during the field visits

Photos Courtesy of Jessica Zelt

Problem

How Does elevation affect Bird migration arrival

dates ?American Redstart/ Setophaga ruticillahttp://sdakotabirds.com/species_photos/american_redstart_2.htm

Hypothesis

It is predicted that the higher in elevation a certain area is, the longer it takes the bird to travel and thus causes a later arrival date because if the Julian Date increases then the elevation has also increased.

Null: If the Julian date decreases then the elevation has decreased and there is no correlation between the two variables.

Yellow Warbler/ Dendroica petechiahttp://www.pbase.com/dadas115/image/129002746

Methods Migration records from New Jersey, Pennsylvania, Maryland, Delaware,

and Virginia from the Bird Phenology Program were scanned onto the desktop using Adobe Standard 7.0.

All Bird cards were transcribed into Microsoft Excel, and the altitude, latitude, and longitude was also found using http://www.gpsvisualizer.com/geocoder/ and transcribed into excel.

All of the data was sorted according Julian Date. Data with migration dates after May 20th, Julian day 120 were deleted. Pivot Charts and Histograms were made for each state and bird species,

and the number of times a Julian date occurred was graphed. Various graphs made, like Julian Day vs. Altitude, Julian Day vs. Latitude

and Year vs. Altitude, to analyze, organize, and view data. Program named Past.exe™ was downloaded to begin statistically

analyzing data. Past.exe™ was used to find the p-value, r2, slope, and intercept for the cumulative states of each species. Data was placed into a chart.

Multiple regression tests were also utilized to analyze the surplus of data comparing Julian date to more than one independent variable.

http://www.pbase.com/dadas115/image/110560030Wilsonia citrina/Hooded Warbler

Results Analysis of Julian Day Vs. Altitude

Species # of Records

Slope

Intercept

P-value r2

Wilsonia citrina 364 15.5 -1808.6 0.908 0.000Setophaga

ruticilla 855 -18.5 -2088.4 0.013 0.007Dendroica petechia 560 -15.6 2014.7 0.000 0.091

Dendroica fusca 393 -20.0 2718.4 0.000 0.041

Results In studying how altitude affected the Julian

date of arrival of the four different Neo-tropical migrants, a total of 2172 migration cards were scanned and analyzed. When the species were analyzed as a whole, all of the data was significant except for the Wilsonia citrina (Hooded Warbler). When the data was shown to be significant it was always extremely significant with P-values at less than 0.05. All of the data placed in the previous chart can also be viewed in the graphs to be shown.

75 80 85 90 95 100 105 110 115 120 125 130 135 140 1450

100

200

300

400

500

600

700

800

R² = 3.70974194727758E-05

Wilsonia citrina

Julian Day

Altit

ude

(met

ers)

100 105 110 115 120 125 130 135 140 1450

100

200

300

400

500

600

700

800

R² = 0.00721931424266109

Setophaga ruticilla

Julian Day

Alti

tude

(m

eter

s)

100 105 110 115 120 125 130 135 140 1450

100

200

300

400

500

600

700

800

R² = 0.0407342446539406

Dendroica fusca

Julian Day

Altit

ude

(met

ers)

100 105 110 115 120 125 130 135 140 1450

100

200

300

400

500

600

700

800

R² = 0.0911218578759373

Dendroica petechia

Julian Day

Altit

ude

(met

ers)

Results of Multiple Regression Tests

Species Variables # of Records P-value F r2 TLatitude Taltitude TyearWilsonia citrina Altitude and Latitude 364 0.0 72.8 0.29 12.06 2.80Dendroica fusca Altitude and Latitude 393 2.6E-04 8.4 0.04 -0.53 -4.05

Setophaga ruticilla Altitude and Latitude 855 3.4E-03 5.7 0.01 2.29 -2.41Dendroica petechia Altitude and Latitude 560 0.0 91.2 0.25 10.73 -6.89Wilsonia citrina Altitude, Latitude, and Year 364 0.0 50.9 0.30 11.23 2.88 -2.3Dendroica fusca Altitude, Latitude, and Year 393 0.0 7.4 0.05 -0.65 -3.87 -2.2

Setophaga ruticilla Altitude, Latitude, and Year 855 0.0 8.4 0.03 2.38 -2.14 -3.7Dendroica petechia Altitude, Latitude, and Year 560 0.0 61.9 0.25 10.86 -6.59 1.6

Multiple Regression Analysis

Conclusion◊ Although the majority of the data did not support the

hypothesis; many significant figures can be drawn from the graphs and charts compiled.

◊ The trend lines for Setophaga ruticilla, Dendroica petechia and Dendroica fusca displayed a weak negative correlation, supporting the null hypothesis.◊ Wilsonia citrina did display a positive but weak correlation.

◊ The r2 values are also very low for all tests. This shows that although the variables studied played a role, they were not the only thing affecting the arrival dates.

◊ Sheds light that the earth and climactic factors may also play a larger role than hypothesized.

◊ Overall the study provided a better insight and understanding of how the variables, mainly altitude, but also latitude, and year, played a role in later arrival dates.

Conclusion (con.)

In conclusion the hypothesis was not supported. It was reasoned that when birds fly, specifically the male, as it arrives to its site and area of breeding instead of landing at the first place it sees the male will look to higher ground, and a more secure habitat to settle. This helps ensure that when the female birds arrive looking for a mate they have the best chance of producing the healthiest offspring, and the likelihood of the survival of themselves and their offspring increases.

Future Research More research will be conducted at

BPP in the near future to study the effects of many other climatic factors. Since elevation was not a key role in the four species tested, this study could also be run again except with using different bird species

Future studies could research fall arrival dates instead of spring arrival dates.

could also look at how birds have responded to climate changes over the years, with controversial topics such as global warming or even the cooling of the earth in past centuries.

Repeat the same study except with a larger sample size, and/or different species.

Acknowledgements I would like to thank my mentor, Jessica

Zelt for always being positive and supportive and providing numerous resources throughout the whole study.

I would like to thank Sam Droege, for always being like second mentor and helping out a lot with my statistics and always giving great direction for the next step in my project

I would also like to thank my parents for their continuous support.