Date of Award

January 2015

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Gary Ritchison

Department Affiliation

Biological Sciences

Second Advisor

David R. Brown

Department Affiliation

Biological Sciences

Third Advisor

Paul V. Cupp

Department Affiliation

Biological Sciences

Abstract

Breeding is an energetically costly activity for birds. If energy-limited, birds may alter their time budgets, reducing time spent in some activities and spending more time in others. To date, no experimental study has investigated the possible effect of food availability on male mate guarding behavior. Additionally, previous results from food supplementation studies are mixed. My objectives were to determine how food supplementation might influence the breeding behavior of male Indigo Buntings (Passerina cyanea). I predicted that, compared to non-supplemented males, food-supplemented males would: 1) spend less time foraging, 2) spend more time singing, 3) spend more time mate guarding, 4) respond more aggressively to a simulated intruder (i.e. playback of conspecific songs in their territories), and 5) have fewer EPY in their nests. Behavioral observations were conducted at the Miller-Welch/Central Kentucky Wildlife Management Area from 8 May – 15 August 2009. Territories of male buntings (N = 30) in my study area were randomly selected for either food supplementation (n = 8) or controls (n = 22). During time budget observations (20 min/day/focal male), all behaviors were noted. To quantify male aggression, playback experiments were conducted on a subset of six food-supplemented males and six non-food-supplemented males, when numerous aggressive-like behaviors were noted. To determine paternity, blood samples were collected from adults and nestlings at 19 nests. DNA was extracted, amplified, and hand-scored on polyacrylamide gels. Males with feeders in their territories spent significantly less time foraging and significantly more time chipping than males without feeders in their territories. Time spent singing and mate guarding was not statistically different between treatment and control males. Differences in aggressive behaviors and the proportion of EPY approached significance with those males with feeders in their territories exhibiting more aggressive-like behaviors and having more EPY in their nests. Of 16 broods, 12 (75%) had at least one EPY and, in those broods, 24 of 43 nestlings (56%) were EPY. My results suggest that when provided with supplemental food, males can spend less time foraging, and in turn, will have more time and energy to devote to other activities. The presence of supplemental food however, has appeared to increase the rates of intruding, neighboring males. When neighboring conspecifics are drawn to territories with supplemental food, more EPC opportunities exist for females on supplemented territories, therefore leading to a greater proportion of EPY for those females and suggesting that female buntings are not using food as an indicator of habitat or male quality. Mate guarding did not act to fully protect paternity and regardless of time spent mate guarding, females, whether mated to food-supplemented males or not, were not guarded for the majority of the time, thereby permitting ample opportunities to seek EPCs themselves. In addition, female buntings do not risk the loss of male provisioning assistance by seeking EPCs.

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