Graduate Theses & Dissertations

Intra-seasonal Variation in Black Tern Nest-site Selection and Survival
Resources and risk are in constant flux and an organism’s ability to manage change may improve their likelihood of persistence. I examined intra-seasonal variation in nest-site selection and survival of a declining wetland bird, the Black Tern (Chlidonias niger surinamensis). I modelled nest site occupancy and survival of early and late-nesting birds as a function of static and dynamic factors. Early-nesting birds selected nest sites based on the degree and direction of habitat change that occurred over the nesting cycle, while late-nesting birds selected sites based on static conditions near the time of nest-site selection. Nest age had the strongest influence on daily survival rate for both early and late-nesting birds, but the shape of this relationship showed intra-seasonal differences. Additionally, early-season survival improved slightly with increasing vegetation coverage and distance between conspecific nests, while late-season survival increased with clutch size. My results suggest that intra-seasonal variation in nest-site selection and survival is driven by changing habitat conditions and predator behavior. Author Keywords: Black Tern, Chlidonias niger surinamensis, daily survival rate, intra-seasonal variation, nest-site selection
Using DNA Barcoding to Investigate the Diet and Food Supply of a Declining Aerial Insectivote, the Barn Swallow (Hirundo rustica)
Barn Swallow (Hirundo rustica) populations have declined in North America over the past 40 years and they are listed as Threatened in Ontario, Canada. Changes in the food supply have been hypothesized as a potential cause of this population decline. I used DNA barcoding to investigate the diet and food supply of Barn Swallows and to determine if the food supply affects their reproductive performance. In two breeding seasons, I monitored nests, collected fecal samples, and monitored prey availability by collecting insects from the habitat surrounding breeding sites using Malaise traps. I used DNA barcoding to identify insect specimens collected from the habitat and to identify prey items from Barn Swallow nestling fecal samples. I found that Barn Swallow nestlings were fed a very broad range of prey items but were fed larger prey items more frequently. Prey availability was not related to the timing of reproduction, the number of nests at a breeding site, or the reproductive output of individual nests. This study provides information on the diet composition of Barn Swallows in North America and suggests that food limitation during the breeding season may not be a major factor in their population decline. Author Keywords: aerial insectivore, diet, DNA barcoding, Hirundo rustica, metabarcoding, reproductive success
THE EFFECTS OF ROTATIONAL GRAZING AND HAY MANAGEMENT ON THE REPRODUCTIVE SUCCESS OF BOBOLINK AND EASTERN MEADOWLARK IN EASTERN ONTARIO
I investigated the impact of beef-cattle farm management on the reproductive success of Bobolink (Dolichonyx oryzivorus) and Eastern Meadowlark (Sturnella magna) within Eastern Ontario. I monitored rotational grazing management regimes and hay cut dates while assessing breeding phenology and reproductive success of Bobolinks and Eastern Meadowlarks. In pasture paddocks the major factor determining Bobolink reproductive success was the date that cattle entered a paddock to graze, with earlier entries resulting in lower reproductive success. On a landscape scale, within a series of paddocks grazed by a single herd, as the number of paddocks grazed during the nesting season increased, the number of Bobolinks that reproduced successfully decreased. Experimental quantification of trampling showed that cattle exposure to clay pigeon targets, regardless of stocking rates, resulted in the majority of targets being trampled. In hayfields associated with beef- cattle operations, grassland birds had a higher likelihood of success when cutting occurred after 4 July. The best method to improve the reproductive success of Bobolinks and Eastern Meadowlarks is to leave some hayfields and pasture paddocks undisturbed until nesting is complete. Author Keywords: Bobolink, Dolichonyx oryzivorus, farm management, hayfield, pasture, rotational grazing
EVALUATION OF HAYFIELD MANAGEMENT STRATEGIES AND BOBOLINK TERRITORIAL HABITAT IN SOUTHERN ONTARIO
I implemented three hayfield management regimens in southern Ontario (a typical schedule at the farmer`s discretion, a delayed first harvest after July 14, and an early first harvest before June 1 with 65 days before second harvest), and evaluated the costs/benefits to farmers regarding hay quality and feasibility, and to Bobolinks (Dolichonyx oryzivorus) regarding reproductive activity and phenology. Typical management resulted in little to no Bobolink reproductive success, and early harvested sites were not (re)colonized. On delayed harvest sites Bobolinks experienced high reproductive success, but hay quality fell below ideal protein levels for most cattle before harvest. I also examined the habitat features Bobolinks use as the basis for establishing territories and associations between Bobolink territory size and habitat quality. I compared vegetation structure, patch size, and prey abundance between small and large territories. Small territories typically occurred on smaller fields with more preferred vegetation characteristics and greater prey abundance. Author Keywords: agro-ecosystem, Bobolink, Dolichonyx oryzivorus, grassland birds, hayfield management

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