Algal blooms are directly related to human-caused nutrient enrichment of water bodies. The cyanobacteria Microcystis aeruginosa produces microcystin (MC), a toxin that has been linked with mortalities and illness of many organisms. We show that MC is not constrained by the aquatic-terrestrial ecotone. MC was detected in a primary consumer and emerging aquatic invertebrate (Hexagenia Mayfly), a terrestrial insect and predator of emerging aquatic invertebrates (Tetragnathidae Spider), and a vertebrate consumer (Prothonotary Warbler). Mayfly and spider MC levels varied across the blooming period. MC levels in prothonotary warbler livers varied by age class; nestlings having the highest levels. MC levels decreased in fledglings over time. A more aquatic diet was related to higher MC levels in nestlings at one site and nestling fecal-sacs varied spatially, also indicating that aquatic diet is related to MC consumption. Warbler body condition and growth rate was not related to liver microcystin levels.

Avian malaria is a devastating disease that has decimated numerous bird species. This study sought to identify the vectors of avian malaria at four central Virginia Prothonotary warbler breeding sites. Twenty one thousand mosquitoes were collected and Culex salinarius, Cx. erraticus, and Cx. pipiens/restuans were found to be the dominant species at these sites. Geographic factors, such as crop land and forest type, were determined to be potential indicators for species abundance variation between sites. Of the mosquitoes collected, ninety one (0.4%) were identified as blood fed. The blood fed mosquitoes were found to have fed on avian, mammalian, amphibian, and reptilian hosts and a 12.1% Plasmodium infection rate. Of the non-blood fed mosquito pools tested, Deep Bottom had the highest rate of infection (10.5%). Of the species tested, Cx. salinarius, Cx. erraticus, and Cx. pipiens/restuans were determined to be the most probable vectors of avian malaria the four sites.

Obligate brood parasites lay their eggs in nests of other species, relying on these host parents to care for their offspring. This phenomenon has been a curiosity amongst researchers since its first description and has become a model study system for testing such ideas as coevolution and species recognition. This thesis examines a few of the many questions that arise from this breeding system. The New Zealand Grey Warbler (Gerygone igata) and its brood parasite, the Shining Cuckoo (Chrysococcyx lucidus) are used as the main study species, although research on the eviction behaviour of Common Cuckoos (Cuculus canorus) has also been conducted. First, the current state of knowledge and recent discoveries regarding nestling rejection abilities of hosts is reviewed in chapter one. Second, a comparative study of New Zealand passerine begging calls has been conducted to test for begging call similarity between a brood parasite and its host, as well as developing a new technique for detecting the mode of coevolution that may be occurring in the parasite – host relationship. Parent-offspring communication in Grey Warblers is also examined to test for both parental and nestlings Parents use both alarm calls to warn offspring of potential danger, and also parental feeding calls to elicit a begging response from nestlings. By contrast, nestlings are able to signal both age and short term levels of need to parents through the acoustic structure of the begging call. The evolutionary costs and benefits of egg eviction behaviour in the Common Cuckoo are also tested. An experimental approach showed that egg eviction had a growth cost, but this cost was temporary and restricted to during and immediately after the egg eviction phase. A pattern of compensatory growth was observed after the eviction period, so that during the later nestling stages there was no difference in mass, and no difference in fledging age. Finally, variation in the Grey Warbler breeding biology and Shining Cuckoo parasitism rates are examined through both time and across latitudes. This research has shown a counterintuitive pattern of breeding phenology across latitudes. These patterns have implications for Shining Cuckoos both in terms of timing of available nests and host selection. Keywords: Begging call, breeding phenology, brood parasitism, coevolution, Common Cuckoo, eviction, Grey Warbler, parent-offspring communication, Shining Cuckoo.

Alarm calls are one of the essential components of antipredator behaviour in birds. In this study I recorded and analysed alarm responses of the barred warbler (Sylvia nisoria) to different mounts of avian predators and nonpredators. The information about danger is encoded through graded structure in its unspecific alarm call type.

The aim of this thesis was to find out the extent of the predation of the Eurasian Reed Warbler (Acrocephalus scirpaceus) during the laying period in the South Bohemian Region. The survey was done by means of artificial nests containing fake eggs. Additional goal of the thesis was to evaluate the factors that can influence the predation according to measured nest parameters, such as the distance of the artificial nest from free water surface, the depth of water below the nest and the distance from the nearest tree.

No description available.

No description available.

Fire suppression, combined with lack of forest thinning and short-rotation, monodominant management, has drastically altered the landscape in the southeastern U.S., leading to the loss of open pine ecosystems and associated avian species. Management of open pine ecosystems is a common practice; yet, there remains uncertainty regarding how vegetation structure impacts priority species. Using empirical data, I assessed changes in species abundance and associated vegetation characteristics before and after management. I also sought to identify vegetation characteristics that influence home range establishment and microhabitat selection of Bachman’s Sparrows. Priority species were negatively associated with hardwood midstory and abundance per site increased following management. Home range establishment of Bachman’s Sparrows was influenced by disturbance, canopy cover, and slope, while microhabitat selection was influenced by pine basal area, available perching options, vegetation density, and herbaceous groundcover. Understanding how vegetation structure impacts priority species may be helpful in guiding conservation and management efforts.

To underpin and improve advice given to government and other interested parties on the state of Britain’s common songbird populations, new models for analysing ecological data are developed in this thesis. These models use data from the British Trust for Ornithology’s Constant Effort Sites (CES) scheme, an annual bird-ringing programme in which catch effort is standardised. Data from the CES scheme are routinely used to index abundance and productivity, and to a lesser extent estimate adult survival rates. However, two features of the CES data that complicate analysis were previously inadequately addressed, namely the presence in the catch of “transient” birds not associated with the local population, and the sporadic failure in the constancy of effort assumption arising from the absence of within-year catch data. The current methodology is extended, with efficient Bayesian models developed for each of these demographic parameters that account for both of these data nuances, and from which reliable and usefully precise estimates are obtained. Of increasing interest is the relationship between abundance and the underlying vital rates, an understanding of which facilitates effective conservation. CES data are particularly amenable to an integrated approach to population modelling, providing a combination of demographic information from a single source. Such an integrated approach is developed here, employing Bayesian methodology and a simple population model to unite abundance, productivity and survival within a consistent framework. Independent data from ring-recoveries provide additional information on adult and juvenile survival rates. Specific advantages of this new integrated approach are identified, among which is the ability to determine juvenile survival accurately, disentangle the probabilities of survival and permanent emigration, and to obtain estimates of total seasonal productivity. The methodologies developed in this thesis are applied to CES data from Sedge Warbler, Acrocephalus schoenobaenus, and Reed Warbler, A. scirpaceus.

Geographic Information Systems (GIS) and remote sensing technologies were used to identify and describe potential habitat for three species endemic to the Southwestern United States; the Golden-cheeked Warbler (Dendroica chrysoparia), the Black-capped Vireo (Vireo atricapillus), and the Texas kangaroo rat (Dipodomys elator). For each species, the computerized classification of digital satellite imagery was integrated with ancillary spatial information (e.g. soils, geology, and land use) to construct a data base to be used for ecological evaluation as well as habitat protection and management measures.