Author ORCID Identifier

https://orcid.org/0000-0002-4978-9087

Date of Award

Spring 4-10-2026

Document Type

Thesis (Ph.D.)

Department or Program

Ecology, Evolution, Environment and Society

First Advisor

Matthew P. Ayres

Second Advisor

Hannah M. ter Hofstede

Abstract

Habitat selection is a key behavior that has consequences for fitness, which can shift with environmental variation. The environment can affect reproductive success indirectly by shaping behavior or via direct impacts. Many forest breeding migratory birds choose a habitat by establishing territories. To understand the interplay of environment and behavior on the reproductive success of forest breeding migratory birds, I leveraged long-term data and newly collected species-specific data from Hubbard Brook Experimental Forest, New Hampshire, USA. I analyzed over 50 years of territory maps from seven species occupying a 10-ha plot to understand how birds distribute themselves in a habitat. Territory size decreased with abundance for all species, irrespective of habitat quality. Within years, territory size varied at least 2-fold. I tested how territory size varied with respect to food availability and habitat structure and the consequences of this variability on reproductive success by studying Ovenbirds (Seiurus aurocapilla) on a 100-ha plot. Territory size varied greatly within years (7–9 fold), and larger territories had more food. But there was no relationship between territory size and reproductive success. Time spent singing might also affect reproductive success through rates of within-pair paternity, or the number of offspring fathered by the social male. Ovenbirds sang more when their female was fertile and when surrounded by more neighbors; however, song rate had no effect on within-pair paternity. In years with similar population density, nest predators and abundant resources may make territory size less valuable for reproductive success. My results suggest that territoriality in forest breeding migratory birds may be driven by the need to adjust space relative to neighbors rather than resource availability. My findings illustrate the efficacy of territorial singing behavior as a mechanism of territoriality and the consequences it has on population dynamics.

Original Citation

Chapter 1:

Zammarelli, M. B., M. P. Ayres, H. M. ter Hofstede, D. A. Lutz, and R. T. Holmes. 2024. Territory sizes and patterns of habitat use by forest birds over five decades: Ideal free or ideal despotic? Ecology Letters 27:e14525.

Download

Share

COinS