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Articles 2011 - 2040 of 4554

Full-Text Articles in Ornithology

Head Stabilization In Whooping Cranes, Matthew R. Kinloch, Thomas W. Cronin, Glenn H. Olsen Jan 2005

Head Stabilization In Whooping Cranes, Matthew R. Kinloch, Thomas W. Cronin, Glenn H. Olsen

Proceedings of the North American Crane Workshop

The whooping crane (Grus americana) is the tallest bird in North America, yet not much is known about its visual ecology. How these birds overcome their unusual height to identify, locate, track, and capture prey items is not well understood. There have been many studies on head and eye stabilization in large wading birds (herons and egrets), but the pattern of head movement and stabilization during foraging is unclear. Patterns of head movement and stabilization during walking were examined in whooping cranes at Patuxent Wildlife Research Center, Laurel, Maryland USA. Four whooping cranes (1 male and 3 females) …


Gordon Natural Area Bird Inventory, West Chester Birding Club Jan 2005

Gordon Natural Area Bird Inventory, West Chester Birding Club

Gordon Natural Area Bird Survey Documents

No abstract provided.


Zur Nahrungsökologie Des Uhus Bubo Bubo In Der Mongolei = Feeding Ecology Of The Eagle Owl Bubo Bubo In Mongolia, Thomas Hoffmann, Michael Stubbe, D. Heidecke, R. Piechocki, R. Samjaa, J. Erfurt, D. Sumjaa Jan 2005

Zur Nahrungsökologie Des Uhus Bubo Bubo In Der Mongolei = Feeding Ecology Of The Eagle Owl Bubo Bubo In Mongolia, Thomas Hoffmann, Michael Stubbe, D. Heidecke, R. Piechocki, R. Samjaa, J. Erfurt, D. Sumjaa

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

This paper presents further results on the food ecology of the eagle owl in western Mongolia for the years 1984 to 1992. Additional to the already known sites we investigated two new resting places. At least 27 mammal and 17 bird species were recorded. The results confirm previous studies. Small to medium sized mammals (Cricetidae, Dipodidae, Arvicolidae) dominate the prey of the eagle owl whereas birds and invertebrates are less important.


Avifaunistische Beobachtungen Im Westchentej, Ulrich Zöphel, Jochen Schulenberg, Wolf-Dieter Busching, Ingolf Todte Jan 2005

Avifaunistische Beobachtungen Im Westchentej, Ulrich Zöphel, Jochen Schulenberg, Wolf-Dieter Busching, Ingolf Todte

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

This paper reports the results of bird observations at four study sites with many different habitats in the western Chentej-mountains (forest steppe, taiga) at the end of the spring-migration and the beginning of the breeding time. Altogether 134 bird species were observed, about 107 of which are probably breeding birds. Additional birds were caught using 6 mist-nets. In this way 98 birds of 21 species were caught, measured, and ringed. Furthermore feathers have been collected (molting feathers and near two breeding places of Accipiter nisus).

The bird fauna of the larch forests shows a high species richness (108 species), …


Das Arteninventar Der Avifauna Der Mongolei Während Einer Nord-Süd-Durchquerung 1997, Tobias Stenzel, Michael Stubbe, R. Samjaa, Annegret Stubbe, C. Dulamsuren Jan 2005

Das Arteninventar Der Avifauna Der Mongolei Während Einer Nord-Süd-Durchquerung 1997, Tobias Stenzel, Michael Stubbe, R. Samjaa, Annegret Stubbe, C. Dulamsuren

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

Here we present a detailed report on bird biodiversity of ecosystems along a North-South transect through Mongolia in 1997whic h serves as a guideline for further research projects and training for students in all Mongolian vegetation zones from northern steppes to southern deserts.

Two hundred fifty-five bird species were observed between 21st of July and 10th of August 1997. The main study sites were located in the North the Selenge-Orchon-basin with meadows and dune woodlands 15 km southern from Suchbaatar, the Middle Gobi-Aimag with desert steppes and sajrs (covered with Ulmus pumila) and in the Bordzongijn-gobi in the South …


Quantitative Investigations On Bird Communities In Different Habitats In The Orkhon-Selenge-Valley In Northern Mongolia, Tobias Stenzel, Michael Stubbe, Ravčigijn Samjaa, Sundev Gombobaatar Jan 2005

Quantitative Investigations On Bird Communities In Different Habitats In The Orkhon-Selenge-Valley In Northern Mongolia, Tobias Stenzel, Michael Stubbe, Ravčigijn Samjaa, Sundev Gombobaatar

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

In the breeding seasons 2001 to 2003, the avifauna of a study area of about 80 km2 in the Selenge Aymag was studied.

The area is characterized by loose groves of elms (Ulmus pumila) and pine trees (Pinus sylvestris), and a chain of barchan dunes which separate the Orkhon valley from the up to 70 m higher situated forest steppe. Steppe species (Stipa spp.) dominate in the south; the northern steppe part is characterized by Caragana bushes (Caragana microphylla, locally C. stenophylla). Between Orkhon Gol and the eastern dunes, dry steppe …


Über Die Federmerkmale Der Mongolischen Sakerfalken Falco Cherrug Milvipes Im Vergleich Zu Den Westlichen Sakerfalken Der Unterart F. Ch. Cherrug Und Bemerkungen Über Die Gefiedermerkmale Des “Altaifalken”, Wolf-Dieter Busching Jan 2005

Über Die Federmerkmale Der Mongolischen Sakerfalken Falco Cherrug Milvipes Im Vergleich Zu Den Westlichen Sakerfalken Der Unterart F. Ch. Cherrug Und Bemerkungen Über Die Gefiedermerkmale Des “Altaifalken”, Wolf-Dieter Busching

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

The different plumage characteristics of the Mongolian Saker Falco cherrug milvipes and the nominate race F. ch. cherrug are discussed. It could be shown that both races are polymorphic. According to Baumgart (1997), Sakers don’t need uniform plumages because they live on nearly blind voles. Due to that there seems to be no selection pressure from victims side. The same phenomenon is observable with Buteo buteo and the typical Mongolian Buteo hemilasius.

Whereas young Sakers of the nominate race cherrug equal more or less already adults, are the differences in the plumage of juv. and ad. milvipes great enough. …


Wpa News 74 (2005), World Pheasant Association Jan 2005

Wpa News 74 (2005), World Pheasant Association

Galliformes Specialist Group and Affiliated Societies: Newsletters

WPA News (Winter 2005), number 74

Published by the World Pheasant Association


The Status And Impact Of The Rainbow Lorikeet (Trichoglossus Haematodus Moluccanus) In South-West Western Australia, Tamara Chapman Jan 2005

The Status And Impact Of The Rainbow Lorikeet (Trichoglossus Haematodus Moluccanus) In South-West Western Australia, Tamara Chapman

Agriculture reports

This report provides a summary of the biology and ecology of the rainbow lorikeet (Trichoglossus haematodus moluccanus), examines the status and management of the rainbow lorikeet in other regions; assesses the threats posed by the feral population in south-west Western Australia; and formulates the aims and objectives for an integrated pest management program.


Grassland And Woodland Bird Occurrence And Habitat Selection In The Prairie-Forest Transition Zone Of Minnesota, Thomas Robert Cooper Jan 2005

Grassland And Woodland Bird Occurrence And Habitat Selection In The Prairie-Forest Transition Zone Of Minnesota, Thomas Robert Cooper

Electronic Theses and Dissertations

Numerous species of woodland and grassland nesting birds have experienced population declines in the midwestern United States. Habitat loss and habitat fragmentation are suspected to be two of the underlying causes for the population declines of woodland and grassland birds. The Minnesota Valley Wetland Management District (WMD) covers 14 counties in southeastern Minnesota in the transition zone between forested and prairie ecoregions. Little information is available relative to which birds are using grassland or woodland habitat within the WMD and how their presence or absence is related to the available habitat conditions. Therefore, my study objectives were to: 1) determine …


Past, Present, And Hypothetical Methods For Crane Reintroduction And Migration, David H. Ellis Jan 2005

Past, Present, And Hypothetical Methods For Crane Reintroduction And Migration, David H. Ellis

Proceedings of the North American Crane Workshop

In the early 1980’s the technique of releasing yearling parent-reared cranes was perfected with the Mississippi sandhill crane (Grus canadensis pulla). In the late 1980’s, we discovered that hand-reared yearlings could also be released with good expectation of survival in both migratory and nonmigratory situations. In the mid-1990’s, efforts expanded in many directions including (1) the use of various types of motorized vehicles to lead migrations, (2) the release of juveniles one by one into wild flocks in autumn or winter, and (3) the release of adult pairs. Here I outline new and proven techniques and those likely …


Initial Training Of Cranes For An Airship Migration, David H. Ellis, Glenn H. Olsen, Jared Kwitowski Jan 2005

Initial Training Of Cranes For An Airship Migration, David H. Ellis, Glenn H. Olsen, Jared Kwitowski

Proceedings of the North American Crane Workshop

We describe the first year of our efforts to train cranes to accept the unnatural stimuli associated with being transported south in cages suspended beneath an airship. All 4 experimental cranes readily acclimated to entering a suspended cage and were trained to accept being jostled while in the cage, even when the cage was transported in the back of a pickup truck. With minor changes, the training protocol is ready for use in an actual airship migration.


Morbidity And Mortality Factors In Pre-Fledged Florida Sandhill Crane (Grus Canadensis Pratensis) Chicks, Robert J. Dusek, Marilyn G. Spalding, Donald J. Forrester, Nicholas Komar, Jonathan F. Day Jan 2005

Morbidity And Mortality Factors In Pre-Fledged Florida Sandhill Crane (Grus Canadensis Pratensis) Chicks, Robert J. Dusek, Marilyn G. Spalding, Donald J. Forrester, Nicholas Komar, Jonathan F. Day

Proceedings of the North American Crane Workshop

One hundred and fifteen Florida sandhill crane (Grus canadensis pratensis) chicks were captured in Osceola and Lake Counties, Florida in 1998 - 2000 and examined for evidence of disease. Evidence of Eimeria gruis and/or E. reichenowi infection was found in 52% of chicks examined. Ten chicks were positive for antibodies to St. Louis encephalitis virus and 1 of these chicks was also positive for antibodies to eastern equine encephalitis virus. Predation was the most commonly identified cause of mortality. An unidentified microfilaria, and an unknown protozoan were detected in blood smears from crane chicks. A number of other …


Nesting Ecology And Productivity Of The Cuban Sandhill Crane On The Isle Of Youth, Cuba, Xiomara Galvez Aguilera, Vicente Berovides Alvarez, Felipe Chavez-Ramirez Jan 2005

Nesting Ecology And Productivity Of The Cuban Sandhill Crane On The Isle Of Youth, Cuba, Xiomara Galvez Aguilera, Vicente Berovides Alvarez, Felipe Chavez-Ramirez

Proceedings of the North American Crane Workshop

We studied nesting ecology and productivity of the Cuban sandhill crane in the Isle of Youth Cuba between 1997-2003. The nesting season extended from late march through June, but due to variable weather conditions could begin in February or extend through July. Overall, 71.1% of nests located produced eggs, while 84.1% of nests with eggs hatched at least one chick. Mean clutch size was 1.72 eggs. There were significant differences in hatching rates (G = 19.05, P < 0.01) and successful nests between years (G = 9.59, P < 0.10). Chicks/successful nest and rainfall during the breeding period (r = 0.6) were positively correlated. Percent successful nests was negatively correlated with total rainfall during the breeding season (r = -0.50). Causes of egg or nest failure included nest abandonment, predation, flooding, and infertility. In regards to breeding biology we recorded feather painting prior to nesting activity, false nests, and a re-nesting attempt after nest destruction. All nests were built on dry land. Cranes selected four of 11 habitat types present in the study area for nesting: open savannah (SNA) (24.2%), semi-closed natural savannah (SSC) (50.67%), open pine woodland (SPPA) (17.7%), and secondary savannah (SS) (7.7%). Palm density, seedlings, and forbs were lower at nest sites compared to random points, while ground cover of sand and litter was greater at nest sites. There were no significant differences in frequency of plant species among nest sites and random points (G = 3.78, P > 0.05). Tree species richness was less at nest sites, likely due to dominance of Tabebuia lepiodphylla and Byrsonima crassifolia species. Significant differences (G …


Definition Of Subpopulations Within Mid-Continent Sandhill Cranes: A Nuclear Approach, K. L. Jones, G. L. Krapu, D. Brandt, M. V. Ashley Jan 2005

Definition Of Subpopulations Within Mid-Continent Sandhill Cranes: A Nuclear Approach, K. L. Jones, G. L. Krapu, D. Brandt, M. V. Ashley

Proceedings of the North American Crane Workshop

The evolution and population dynamics of migratory sandhill cranes (Grus canadensis) have been the subject of many studies. Although these previous studies have made significant progress explaining sandhill evolution on a large scale, they have been insufficient to explain the geographically partitioned variation in morphology seen in this species. The objective of this study is to quantify the population structure and/or gene flow within and between migratory sandhills using 12 microsatellite DNA loci and 192 samples collected across three populations. Contrary to the lower rates of gene flow seen between the three major migratory populations, high rates of …


Annual Movements Of Pacific Coast Sandhill Cranes, Gary L. Ivey, Caroline P. Herziger, Thomas J. Hoffmann Jan 2005

Annual Movements Of Pacific Coast Sandhill Cranes, Gary L. Ivey, Caroline P. Herziger, Thomas J. Hoffmann

Proceedings of the North American Crane Workshop

The subspecies composition of migratory sandhill cranes (Grus canadensis) which stage and winter along the Lower Columbia River in northwest Oregon and southwest Washington is uncertain, but may include all 3 using the Pacific Flyway: lesser (G. c. canadensis), Canadian (G. c. rowani), and greater (G. c. tabida). However, the status of rowani has been debated. During 2001-02, we captured and marked 8 cranes using a noose line trapping technique, and attached Platform Transmitter Terminals (PTTs) to 6 to ascertain locations of their breeding areas, migration corridors and winter sites. Morphometric data …


Capture Of Sandhill Cranes Using Alpha-Chloralose, Matthew A. Hayes, Barry K. Hartup, Jeanne Marie Pittman, Jeb A. Barzen Jan 2005

Capture Of Sandhill Cranes Using Alpha-Chloralose, Matthew A. Hayes, Barry K. Hartup, Jeanne Marie Pittman, Jeb A. Barzen

Proceedings of the North American Crane Workshop

From 1990 – 2001, 188 captures of 166 different greater sandhill cranes (Grus canadensis tabida) were made through the experimental use of alpha-chloralose (AC) in Wisconsin (Hayes et al., 2003). Captures occurred in August (n = 28, 15%), September (n = 136, 72%) and October (n = 24, 13%). Capture of all members in the target social group was relatively high (59%). Territorial pairs were captured more successfully (2 of 2 cranes were captured 69% of the time) than family groups (3 of 3 cranes were captured 50% of the time, and 4 of 4 cranes were captured …


An Obligation To Publish, Stephen A. Nesbitt Jan 2005

An Obligation To Publish, Stephen A. Nesbitt

Proceedings of the North American Crane Workshop

To be justifiable any wildlife study should strive to attain and describe new knowledge or refine existing understanding. Published results of field studies are often the products that conclude the study, though not always. But, as E.O. Wilson wrote in Consiliance: The Unity of Knowledge, “One of the structures of the scientific ethos is that a discovery does not exist until it is safely reviewed and in print.” Putting knowledge to page requires effort and, frequently, the abandonment of ones own ego. However, ego notwithstanding, this is not the only reason to publish research findings. Whether we are trying to …


Injuries And Abnormalities Of Sandhill Cranes Captured In Florida, Stephen A. Nesbitt, Marilyn G. Spalding, Stephen T. Schwikert Jan 2005

Injuries And Abnormalities Of Sandhill Cranes Captured In Florida, Stephen A. Nesbitt, Marilyn G. Spalding, Stephen T. Schwikert

Proceedings of the North American Crane Workshop

Observations of gross pathological abnormalities were made during handling of sandhill cranes (Grus canadensis) captured for banding in Florida. One hundred fifty-six of 1,331 (11.7%) cranes examined showed evidence of one or more anomalies that were the result of disease, congenital deformity, or injury. Most frequent were abnormalities of the legs and feet, followed by abnormalities of the bill. Injuries of the eyes, head, and neck were also noted. Many of these birds were observed subsequent to banding and survived for several years with their injuries, though some never succeeded in reproducing.


International Crane Foundation Sponsored Environmental Education: Conservation Of The Cuban Sandhill Crane, Korie M. Klink Jan 2005

International Crane Foundation Sponsored Environmental Education: Conservation Of The Cuban Sandhill Crane, Korie M. Klink

Proceedings of the North American Crane Workshop

The International Crane Foundation (ICF) has supported crane conservation, education and research activities in Cuba since 1995. Groups of American educators and researchers visit the island, contributing to annual crane festivals, school activities, survey work, assessments and cross-cultural communication. The goals of ICF’s environmental education program in Cuba are to: Disseminate information about ICF and crane conservation to American and Cuban educators and students, and to empower them to carry on ICF’s mission in their classrooms and communities; Participate actively in the Cuban Crane Festival while interacting with and supporting Cuban educators, biologists, and professionals; Develop activities, educational programs and …


Genetic Assessment Of Non-Migratory Sandhill Crane Populations, K. L. Jones, F. Chavez-Ramirez, X. Galvez-Aguilera, L. Torella, M. V. Ashley Jan 2005

Genetic Assessment Of Non-Migratory Sandhill Crane Populations, K. L. Jones, F. Chavez-Ramirez, X. Galvez-Aguilera, L. Torella, M. V. Ashley

Proceedings of the North American Crane Workshop

Partial migration, the tendency of a segment of a population to remain resident while others migrate between their seasonal breeding and wintering ranges, is well known for many bird species. The objective of this study is to quantify the population structure and historical and recent gene flow patterns among non-migratory sandhills using microsatellite DNA genotyping of a large number of sandhills collected from six populations; and to assess if the population subdivisions are consistent with theories of partial migration. Our results indicate a complex web of gene flow within non-migratory populations, as well as between migratory and non-migratory populations. Gene …


Proceedings Of The Ninth North American Crane Workshop, January 17–20, 2003, Table Of Contents Jan 2005

Proceedings Of The Ninth North American Crane Workshop, January 17–20, 2003, Table Of Contents

Proceedings of the North American Crane Workshop

No abstract provided.


Reintroduction Techniques: Post-Release Performance Of Sandhill Cranes (1) Released Into Wild Flocks And (2) Led On Migration By Ultralight Aircraft, Richard P. Urbanek, Joseph W. Duff, Scott R. Swengel, Lara E. A. Fondow Jan 2005

Reintroduction Techniques: Post-Release Performance Of Sandhill Cranes (1) Released Into Wild Flocks And (2) Led On Migration By Ultralight Aircraft, Richard P. Urbanek, Joseph W. Duff, Scott R. Swengel, Lara E. A. Fondow

Proceedings of the North American Crane Workshop

Two methods of reintroducing a migratory population of whooping cranes (Grus americana) were tested with costume/ isolation-reared juvenile greater sandhill cranes (G. canadensis tabida): (1) release into wild flocks during autumn staging and (2) leading on autumn migration by ultralight aircraft. Birds in the first group were released singly, and all integrated quickly into the wild flocks and adopted similar behavioral patterns. Birds in the second group were led to winter on an inland site on the Gulf Coast of Florida. Most of the birds led by ultralight aircraft remained in their juvenile cohort through the …


Sandhill Crane Use Of Managed Chufa Wetlands In New Mexico, John P. Taylor, Loren M. Smith Jan 2005

Sandhill Crane Use Of Managed Chufa Wetlands In New Mexico, John P. Taylor, Loren M. Smith

Proceedings of the North American Crane Workshop

Natural wetland food plants help meet energetic requirements for sandhill cranes (Grus canadensis). Chufa (Cyperus esculentus) tubers were found to be a prominent item in the winter diet of cranes in New Mexico and Texas. In 1996 and 1997, chufa production was compared among mowing, discing, and sustained-flooding treatments intended to enhance chufa tuber growth. Sandhill crane numbers were monitored on wetlands during winter flooding to determine treatment preferences. No differences in sandhill crane use of treated wetlands were found in 1996, however in 1997, crane use was higher on disked field than sustained flood fields …


An Adaptive Approach To Channel Management On The Platte River, Kent Pfeiffer, Paul Currier Jan 2005

An Adaptive Approach To Channel Management On The Platte River, Kent Pfeiffer, Paul Currier

Proceedings of the North American Crane Workshop

The mission of the Platte River Whooping Crane Maintenance Trust is to protect and manage habitat in the Platte valley for whooping cranes, sandhill cranes, and other migratory birds. The plan for meeting this mission calls for the creation and maintenance of eleven habitat complexes distributed through the central Platte valley. Each habitat complex is intended to consist of 1,000 ha of wet meadows and adjacent roost habitat of open, unvegetated river channel. Reduced flows in the river have caused its channel to narrow with banks that are often heavily wooded. Formerly mobile sand bars have stabilized and support dense …


Migration Chronology, Routes, And Distribution Of Pacific Flyway Population Lesser Sandhill Cranes, Michael J. Petrula, Thomas C. Rothe Jan 2005

Migration Chronology, Routes, And Distribution Of Pacific Flyway Population Lesser Sandhill Cranes, Michael J. Petrula, Thomas C. Rothe

Proceedings of the North American Crane Workshop

Managers of migratory game birds require accurate information about bird movements to delineate populations, protect important habitats, and regulate harvest. Data describing movements of sandhill cranes (Grus canadensis) belonging to the Pacific Flyway Population (PFP) are lacking. We used satellite telemetry to monitor movements of PFP lesser sandhill cranes (Grus c. canadensis) captured in the upper Cook Inlet and Bristol Bay regions of Alaska. Satellite transmitters were deployed on 19 flightless young (colts) and 3 adults over 3-years (2000-2002). Chronology, routes, and stopover or staging areas were identified for fall and spring migration periods. On average, …


Possible Recent Range Expansion Of Alcataenia Longicervica (Eucestoda: Dilepididae) Parasitic In Murres Uria Spp. (Alcidae) Into The North Atlantic [Short Communications], Sabir B. Muzaffar, Eric P. Hoberg, Ian L. Jones Jan 2005

Possible Recent Range Expansion Of Alcataenia Longicervica (Eucestoda: Dilepididae) Parasitic In Murres Uria Spp. (Alcidae) Into The North Atlantic [Short Communications], Sabir B. Muzaffar, Eric P. Hoberg, Ian L. Jones

Harold W. Manter Laboratory of Parasitology: Faculty Publications

A wide range of helminths has been recorded from murres Uria spp. (Threlfall 1971, reviewed by Hoberg 1984a, Muzaffar & Jones 2004). Of the cyclophyllidean cestodes that parasitize murres, the genus Alcataenia Spasskaya 1971 (Dilepididae) is represented by ten species, eight of which are restricted and specific to the auks; the other two species occur in gulls (Laridae). The intermediate hosts of Alcataenia are euphausiid crustaceans such as species of Thysanoessa (Shimazu 1975), which also form an important dietary component of breeding and wintering murres, particularly Thick-billed Murres Uria lomvia (Gaston & Noble 1985, Birkhead & Nettleship 1987, Elliot et …


Effects Of Endogenous Steroid Hormone Levels On Annual Survival In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown, Samrrah A. Raouf, Linda C. Smith, John C. Wingfield Jan 2005

Effects Of Endogenous Steroid Hormone Levels On Annual Survival In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown, Samrrah A. Raouf, Linda C. Smith, John C. Wingfield

School of Biological Sciences: Faculty Publications

The hormone corticosterone is an important part of animals’ response to environmental stress, modulating short-term adaptive changes in behavior and physiology. The hormone testosterone is also critical, especially for males, in regulating the expression of sexual behavior and parental care. These hormones can have costly consequences, however, and within populations individuals show variation in endogenous levels of both corticosterone and testosterone. We studied how annual survival varied as a function of natural levels of these hormones in colonially breeding Cliff swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, USA, in 2000–2003. We sampled hormone levels of birds caught at colonies …


Testosterone And Group Size In Cliff Swallows: Testing The “Challenge Hypothesis” In A Colonial Bird, Linda C. Smith, Samrrah A. Raouf, Mary Bomberger Brown, John C. Wingfield, Charles R. Brown Jan 2005

Testosterone And Group Size In Cliff Swallows: Testing The “Challenge Hypothesis” In A Colonial Bird, Linda C. Smith, Samrrah A. Raouf, Mary Bomberger Brown, John C. Wingfield, Charles R. Brown

School of Biological Sciences: Faculty Publications

The “challenge hypothesis” states that increases in testosterone levels of male animals during the breeding season are directly related to the extent of intrasexual competition for resources or mates that they experience. Although often tested in territorial species, the challenge hypothesis has not been evaluated for colonial animals that live in groups of different sizes and that thus experience different intensities of intrasexual competition. We measured circulating testosterone levels of male and female cliff swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, where these birds nest in colonies of widely different sizes. Males had significantly higher testosterone levels than females, …


A Study Of The Abundance, Distribution And Daily Activities Of The Australian Raven (Corvus Coronoides) In Urban Wetland Parks, Desiree L. Moon Jan 2005

A Study Of The Abundance, Distribution And Daily Activities Of The Australian Raven (Corvus Coronoides) In Urban Wetland Parks, Desiree L. Moon

Theses : Honours

Habitat destruction as a result of urbanisation has resulted in the population decline of some bird species. However, the Australian Raven (Corvus coronoides), has adapted well to the urban environment and is thriving. Although naturally occurring seasonal food sources are at times restricted in an urban setting, this adaptive species finds alternative food sources. As carrion-eaters this includes roadkill, as well as refuse discarded on the ground and into bins. Coupled with few natural predators, the species enjoys optimal conditions for breeding and survival. This biogeographical study investigated whether seasonal-influxes of populations of ravens cause problems at three urban wetland …