Foraging habitats and foraging behavior for seven species of Tyrannid flycatchers were measured to examine interspecific habitat resource partitioning, niche breadth and niche overlap. Four of the species inhabited forested areas; Great Crested Flycatcher, Eastern Wood Pewee, Least Flycatcher and Acadian Flycatcher. Two species, the Eastern Kingbird and Willow Flycatcher, were found in open habitats and one species, the Eastern Phoebe, was found in both open and woodland habitats. Among forest species of flycatchers and open habitat species there was considerable similarity in vegetational characteristics of the foraging habitat. Contrary to previously published studies, these similarities contributed to a high degree of resource overlap among syntopic species of forest flycatchers. A similar degree of overlap was also observed among the open habitat species. Much of the resource overlap among species was attributable to the large resource (habitat) breadth of the Willow Flycatcher and Eastern Wood Pewee. Overlap in foraging habitat among the species was reduced by their using other means of resource partitioning within habitats. Most notably, vertical stratification effectively separated most forest species. The use of different foraging substrates and different foraging tactics (sortie flight distance and methods of insect capture) were also important means of partitioning the food resource. Data were analyzed to test a previously published hypothesis which indicated that the foraging ecology of a smaller flycatcher species was affected by the presence of a larger syntopic competitor. To test this hypothesis, the Willow Flycatcher and Eastern Wood Pewee were selected because they had large resource breadths (ecologically plastic) and because sampling for both species included habitats which were syntopic and nonsyntopic with their respective competitors, the Eastern Kingbird and Great Crested Flycatcher. Both smaller species displayed a reduction in resource breadth in areas of syntopy. Therefore, these data tend to support the published hypothesis and indicate habitat accommodation on the part of the smaller species, in the presence of a larger competitor. / Ph. D.

Survivorship (the likelihood of survival from one year to the next) and breeding dispersal (movement between breeding seasons) exhibit considerable variability at both the inter- and intraspecific levels. Using eight years of data (2008-2015), from my study site in southwest Oklahoma, I characterized survivorship and breeding dispersal of the Scissor-tailed Flycatcher (Tyrannus forficatus) in a mixed-grass prairie ecoregion. My results suggest that estimated survivorship of Scissor-tailed Flycatchers is low, especially to the congeneric Eastern Kingbird (T. tyrannus), and was likely underestimated due to the tendency of Scissor-tailed Flycatchers to disperse long distances.

Speciation lies at the heart of evolution and the study of reproductive barriers allows a better understanding of the different steps leading to the complete isolation of two species. Pre-mating (behavior tactics, habitat or food divergence, phenotypic divergence and assortative mating) and post-mating, post-zygotic isolation barriers (selection against unfit hybrids) are well studied in numerous species, but little is known about what is happening between insemination and fertilization (post-mating, pre-zygotic isolation barriers). In this study, we chose the well-studied population of pied and collared flycatchers (Ficedula hypoleuca and F. albicollis) of the hybrid zone of Öland, Sweden, to investigate possible patterns of gamete divergence between these two closely related species. We compared sperm morphology between the two species and their hybrids, analyzing traits that are thought to play an important role in the fertilization success of the males. We did not detect any divergence in sperm morphology between the two species, but we report an extreme reduction of sperm production in hybrid males, as well as spermatogenesis dysfunctions and particularly high rates of extra-pair young in the nests of hybrid males.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Univ., 2007. / Härtill 5 uppsatser. Med sammanfattning på svenska och polska.

The closely related species pied flycatcher (Ficedula hypoleuca) and collared flycatcher (F. albicollis) co-occur on the Swedish island of Öland, where they compete over similar resources. The majority of male pied flycatchers have been found to incorporate elements of the collared flycatcher song in their repertoire. Given that birdsong is partly inherited and partly learned, the relative contribution of genetic predispositions versus acoustic stimuli varies across different species. The results show that in pied flycatchers, song acquisition is tightly correlated with imprinting, and can therefore be greatly influenced by heterospecific tutors in their surroundings, i.e. male collared flycatchers. I found that pied males are capable of not only memorizing collared song elements, but also producing them with high fidelity. Thus, I infer that pied flycatchers are characterized by a high degree of vocal plasticity.

Thesis (M.S.)--University of Minnesota, 2001. / Includes bibliographical references (leaves 47-51) Also available on the World Wide Web as a PDF file.

The endangered willow flycatcher (Empidonax traillii) breeds in mountain meadows in the Sierra Nevada, which have been intensively modified, especially reducing meadow wetness, which favors easy access for mammalian predators to reach nesting areas in the meadow interior. High nest predation frequency is one of the main factors for willow flycatcher and other passerines? populations decline. I conducted trapping in wet and dry areas on 10 meadows in May?August of 2007 and 2008 to identify the assemblage of potential mammalian nest predators. I compared the predator activity between wet and dry areas of the meadows and determined the relationship between predator activity with vegetation and hydrology of the meadows. In 2008, I used radio-telemetry on deer mice (Peromyscus maniculatus) and yellow-pine chipmunks (Tamias amoenus) to determine their movement patterns across wet and dry areas, and between forest and meadow. My results showed that chipmunks? and squirrels? activity was restricted almost to dry areas. The activity of yellow-pine chipmunks was 96% and 97% higher in dry versus wet areas in 2007 and 2008, respectively. Voles, mice, and shrews were active in both site types. Voles (Microtus spp.) and shrews (Sorex spp.) were in general more active in wet areas versus dry areas in 2007. Deer mice were equally active in both site types in 2007 and more active in wet areas in 2008. Between years, predators were 68% more active in wet areas in 2007 compared to 2008, and similarly 52% more active in dry areas. Radio-tagged deer mice used the forest and the meadow and were more common in dry areas, whereas yellowpine chipmunks used more the forest than the meadows and were active only in dry areas. Passerines nesting in drier areas are exposed to a larger assemblage of potential predators and are more likely to be predated. My results suggest that increasing the proportion of inundated areas in the meadows would help reduce predator activity (especially chipmunks and squirrels) and consequently nest predation, helping increase flycatcher numbers. In addition, wetter conditions will favor an increment in food availability for flycatchers and an increment in willow cover, which consequently will provide more nesting substrate and will help increase nest concealment.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.

Mionectes oleagineus (Aves, Tyrannidae) is a small, sexually monomorphic, lek breeding bird. The behaviour and mating system of this species were studied on Costa Rica's Osa Peninsula over two years. In this thesis I ask three questions: 1) What kind of social organization does M. oleagineus exhibit? 2) Does habitat influence male display dispersion? and 3) What is the function of song in attracting mates and in male-male interactions? In Chapter 2, I describe M. oleagineus' social organization. There were three categories of males: territory owners, satellites and floaters. The latter 2 categories were non-territorial and represented half of the male population. I describe interactions between displaying males and visitors to their territories, including courtship display and aggressive interactions between males. Male display dispersion was highly variable in the study area, including classical leks, in which territories shared contiguous boundaries, an exploded lek, where the territories did not share boundaries, and solitary display territories. In Chapter 3, I test the hypothesis that the number of males that can settle in an area, and their subsequent display dispersion, is determined by the availability and dispersion of suitable habitat. Discriminant function analysis of measures of vegetation structure from both territories and non-territory sample plots showed that territory habitat could be distinguished from non-territory habitat. Eleven percent of the sample plots were described as suitable habitat in the analysis. Given that half the male population is non-territorial, the existence of unoccupied, suitable habitat makes it unlikely that habitat availability determines the number of males settling, or their display dispersion. The major occupation of males on their display territories is singing. In Chapter 4, I investigate the function of song for M. oleagineus using behavioural observation and an experiment involving temporary muting. Males which sang at higher rates received more visitors of both sexes. The territories of most muted territorial males were rapidly usurped by other males. Two of the muted males regained their territories upon regaining the ability to sing. This study is the first to directly demonstrate a key role for song in male-male interactions on leks. It also provides evidence that females use song in mate assessment. / Science, Faculty of / Zoology, Department of / Graduate