SEASONAL MIGRATION AND DIET USE IN A NEOTROPICAL COMMUNITY OF AND BATS by Kevin C. Fraser M.Sc., Queen’s University, 2006

A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of

Doctor of Philosophy in Biology

in the Graduate Academic Unit of Biology

Supervisor: Antony W. Diamond, Ph.D., Department of Biology and Faculty of Forestry and Environmental Management

Examining Board: R. Cunjak, Ph.D., Department of Biology S. Heard, Ph.D., Department of Biology

This thesis is accepted by the Dean of Graduate Studies

THE UNIVERSITY OF NEW BRUNSWICK May, 2011

© Kevin C. Fraser, 2011 ABSTRACT

Temperature varies seasonally only slightly in the Neotropics but birds and bats show distinct seasonality in the timing of energetic events such as breeding, moulting and migration. This thesis explores the seasonality of diet, microhabitat use and altitudinal migration of birds and bats in a Nicaraguan cloud forest, using advanced methods in stable-isotope analysis to track diet and migration. I test several hypotheses proposed to explain the variation in stable-hydrogen isotope ratios (δD) in tissues.

I used δD analyses of claws, feathers, , fruit and precipitation to show, for the first time, that micro-spatial and temporal factors, diet, species and body size all significantly influence δD values in a Neotropical cloud forest bird community. I also examined the utility of δD analyses for tracking altitudinal migration in bats. I conclude that broad local variation may limit the use of δD to track birds and bats over large distances but also suggests new applications for tracking seasonal micro-scale habitat use and moult in cloud forest and agroecosystems. Using mark-recapture methods I observed a Neotropical hummingbird (Amazilia cynaura) that migrates altitudinally to moult.

Movement upslope is usually associated with breeding but this was not the case in A. cyanura. This is the first documented example of a hummingbird, or any Neotropical bird, migrating to moult. Using stable-nitrogen isotope analyses of bird tissues I conducted the first test of the diet complementation hypothesis in a community of free- living tropical birds. I predicted that birds would increase their protein consumption during breeding and moulting to meet their energetic and nutritional needs. I show that most species (11 of 14) increased their protein consumption during the breeding and moulting period. These results suggest that seasonal appetites for specific nutrients may

ii influence food selection in Neotropical birds. My conclusions support studies and theoretical work that make a link between rainfall seasonality and the timing of migration, breeding and moulting in Neotropical birds and bats. Future research should be aimed at determining the link between the energetic and nutritive needs of birds and bats and the timing of these behaviours.

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ACKNOWLEDGEMENTS

I thank my supervisor, Dr. Tony Diamond, and committee members, Dr. Richard

Cunjak and Dr. Stephen Heard, for their valuable input throughout the project. I thank

Liliana Chavarría and Georges Duriaux for introducing me to the birds of ‘El Jaguar’, for providing invaluable information on the study area and for their strong efforts, support and encouragement in sample and data collection. The following institutions provided financial and or logistical support for this thesis: Atlantic Cooperative Wildlife Ecology

Research Network, Natural Sciences and Engineering Research Council, and Bat

Conservation International. Wayne Arendt of the U.S. Forest Service and Cuentas

Criticas Project, Marvin Torrez and María Alejandra Martínez Salinas provided samples.

I am grateful to those who provided field support and the hard work of field as