Open Access. Powered by Scholars. Published by Universities.®

Behavior and Ethology Commons

Open Access. Powered by Scholars. Published by Universities.®

Birds

Discipline
Institution
Publication Year
Publication
Publication Type
File Type

Articles 1 - 30 of 35

Full-Text Articles in Behavior and Ethology

Observations On A 40-Year January Bird Census In Boone County, Nebraska, 1978–2017, Wayne Mollhoff Sep 2023

Observations On A 40-Year January Bird Census In Boone County, Nebraska, 1978–2017, Wayne Mollhoff

Zea E-Books Collection

For 40 years Wayne Mollhoff conducted a personal bird census every January. He explains: "After having run several Breeding Bird Survey routes, and participated in several Christmas Bird Counts, I became curious to see what might be found on a winter count under the more tightly controlled parameters of a census, as contrasted with Christmas counts done with variable numbers of observers."

The count was set up similarly to the USGS Breeding Bird Survey routes with 50 stops, one-half mile (800 meters) apart, all birds counted for 3 minutes, with birds counted at one stop not counted again at following …


Quantitative Song Variety In Relation To Genotype In A Hybridizing Chickadee Population, Shelby Madison Palmer Jan 2023

Quantitative Song Variety In Relation To Genotype In A Hybridizing Chickadee Population, Shelby Madison Palmer

MSU Graduate Theses

The Black-capped chickadee (Poecile atricapillus) and Carolina chickadee (P. carolinensis) are North American songbird species that hybridize in a narrow contact zone stretching latitudinally from New Jersey to Kansas, USA. The association between genetic ancestry and song type in this hybrid zone has been studied independently several times and found to be minimal or absent, likely due to the influence of cultural transmission on learned song in the oscine passerine clade to which the chickadees belong. Despite this, the song of both species remains remarkably distinct in allopatry, suggesting a genetic constraint on certain qualities of …


Intrasexual Territoriality, Degree Of Aggression, And Duet Function In The Carolina Wren (Thryothorus Ludovicianus), Danny Zapata Jan 2022

Intrasexual Territoriality, Degree Of Aggression, And Duet Function In The Carolina Wren (Thryothorus Ludovicianus), Danny Zapata

MSU Graduate Theses

Territorial behavior is fundamental for the reproductive success of many species. In many monogamous birds, mated pairs defend year-round territories from conspecifics. Males and females often participate in such interactions in a seemingly cooperative fashion. Furthermore, many of them have developed complex vocal interactions known as duets, in which one member of a pair overlaps its partner’s song in a more or less coordinated fashion, apparently to cooperate in territory defense. However, males and females often respond differently depending on the sex of the intruder; they differ in the degree and mode of aggression displayed during these interactions, and the …


Social And Ecological Correlates Of Avian Infection By Haemosporidian Blood Parasites, Ian R. Hoppe Aug 2021

Social And Ecological Correlates Of Avian Infection By Haemosporidian Blood Parasites, Ian R. Hoppe

School of Natural Resources: Dissertations, Theses, and Student Research

Haemosporidian parasites are a significant source of morbidity and mortality for birds. There is growing recognition of the negative consequences of haemosporidian infections for wild birds at individual and population levels. Avian haemosporidians are geographically widespread, have been detected from a phylogenetically diverse array of hosts, and have been the focus of extensive research due to their impacts on birds and their similarity to vector-borne diseases of humans. However, factors influencing haemosporidian transmission, especially transmission between species, are poorly understood. To better understand these influences, we compared prevalence and diversity of haemosporidian blood parasite infections among species in a behaviorally …


S Is For Sandhill: A Crane Alphabet, Paul A. Johnsgard Apr 2021

S Is For Sandhill: A Crane Alphabet, Paul A. Johnsgard

Zea E-Books Collection

This is a book of cranes, from A to Z, written and illustrated by the world’s foremost authority on the 15 species of these wonderful and ancient birds. It is a book for all ages, and for all who love and marvel at the beauty, order, and variety of the natural world.

Cranes exhibit complex behavior, pair-bonding, and fascinating social interactions. They migrate huge distances, crossing continents, oceans, and mountains between their nesting and wintering areas. Seven of the world’s 15 crane species are listed as “vulnerable,” three as “endangered,” one as “critically endangered,” and only three as of “least …


Evaluating The Effect Of Time Of Day On Singing Behavior In Anna’S Hummingbirds, Adrian D. Macedo, Maxine R. Mota Sep 2019

Evaluating The Effect Of Time Of Day On Singing Behavior In Anna’S Hummingbirds, Adrian D. Macedo, Maxine R. Mota

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

No abstract provided.


Traffic Noise And Sexual Selection: Studies Of Anthropogenic Impact On Bird Songs And Undergraduate Student Reasoning Of Evolutionary Mechanisms, Sarah Spier Aug 2019

Traffic Noise And Sexual Selection: Studies Of Anthropogenic Impact On Bird Songs And Undergraduate Student Reasoning Of Evolutionary Mechanisms, Sarah Spier

School of Natural Resources: Dissertations, Theses, and Student Research

Humans have transformed much of the natural landscape and are continuing to do so at an accelerated rate, compromising natural areas that serve as important habitat for many species. Roads impact much of the environment as they fragment habitat and introduce traffic noise into the acoustic environment, deferentially affecting wildlife in roadside habitat. I explored how traffic noise affects the detection of birds based on whether their vocalizations were masked by traffic noise. Masked species detection was not affected by an increase in traffic noise amplitude, while there was a negative effect of traffic noise amplitude on unmasked species detection, …


Where Birds Chill: An Assessment Of The Habitat Preferences Of Birds Overwintering In Hudson Valley Forests, Elizabeth Claire Axley Jan 2019

Where Birds Chill: An Assessment Of The Habitat Preferences Of Birds Overwintering In Hudson Valley Forests, Elizabeth Claire Axley

Senior Projects Spring 2019

Many avian species overwinter in eastern North America; however, studies on bird populations are rarely undertaken during this critical survival time, and little is known as to their habitat preferences and foraging behavior. In this observational study, we performed a survey of birds overwintering in the Hudson Valley’s temperate, primarily-deciduous forests, assessing avian populations’ habitat preferences through the vegetative structural variables surrounding overwintering birds as they forage. Our results suggest that high canopy cover is critically important to predicting overwintering bird occupancy on a microhabitat scale. Moreover, overwintering birds preferentially occupy forest plots not dominated by sugar maples, in spite …


Stable Isotopes Reveal Opportunistic Foraging In A Spatiotemporally Heterogeneous Environment: Bird Assemblages In Mangrove Forests, Christina Buelow, April Reside, Ronald Baker, Marcus Sheaves Nov 2018

Stable Isotopes Reveal Opportunistic Foraging In A Spatiotemporally Heterogeneous Environment: Bird Assemblages In Mangrove Forests, Christina Buelow, April Reside, Ronald Baker, Marcus Sheaves

University Faculty and Staff Publications

Environmental heterogeneity can foster opportunistic foraging by mobile species, resulting in generalized resource and habitat use. Determining species’ food web roles is important to fully understand how ecosystems function, and stable isotopes can provide insight into the foraging ecology of bird assemblages. We investigated flexibility of food choice in mangrove bird assemblages of northeast Australia by determining whether species’ carbon and nitrogen isotopic values corresponded to foraging group classification described in the literature, such as groups of species that are omnivorous or insectivorous. Subsequently, we evaluated foraging group isotopic niche size, overlap, degree of individual specialization, and the probable proportions …


Bird Population Changes Following The Establishment Of A Diverse Stand Of Woody Plants In A Former Crop Field In North Dakota, 1975– 2015, Lawrence D. Igl, Harold A. Kantrud, Wesley Newton Apr 2018

Bird Population Changes Following The Establishment Of A Diverse Stand Of Woody Plants In A Former Crop Field In North Dakota, 1975– 2015, Lawrence D. Igl, Harold A. Kantrud, Wesley Newton

USGS Northern Prairie Wildlife Research Center

Changes in the coverage of trees and shrubs on the North Dakota landscape since Euro- American settlement have likely had a pronounced impact on bird species that favor woody vegetation. Long- term data sets on breeding bird populations in wooded habitats in North Dakota or in the Great Plains are scarce. In 1975 a wildlife habitat plot was established in a 10.5 ha cropland field with a long history of small- grain production. Th e objective of this article is to evaluate the successional changes in bird populations as the habitat at this site became more biologically and structurally complex …


The Role Of Song In Reproductive Isolation In A New Secondary Contact Zone Of White-Crowned Sparrows (Zonotrichia Leucophrys), William Brooks Jan 2018

The Role Of Song In Reproductive Isolation In A New Secondary Contact Zone Of White-Crowned Sparrows (Zonotrichia Leucophrys), William Brooks

Summer Research

Within the past thirty years, two formerly isolated subspecies of white-crowned sparrows (Zonotrichia leucophrys) have formed an overlap in geographic range. This creates a natural experiment in speciation and reproductive isolation. Understanding how song acts as a reproductive barrier in this overlap can contribute to our understanding of behavioral isolation. We preformed playback experiments on territorial males to measure subspecific vocal discrimination. Additionally, we looked to see if hybridization was occurring. In the playback experiments we found that Z. l. pugetensis discriminates more strongly between songs, while Z. l. gambelii demonstrates little to no difference in response. We …


The North American Quails, Partridges, And Pheasants, Paul A. Johnsgard Oct 2017

The North American Quails, Partridges, And Pheasants, Paul A. Johnsgard

Zea E-Books Collection

This book documents the biology of six species of New World quails that are native to North America north of Mexico (mountain, scaled, Gambel’s, California, and Montezuma quails, and the northern bobwhite), three introduced Old World partridges (chukar, Himalayan snowcock, and gray partridge), and the introduced common (ring-necked) pheasant. Collectively, quails, partridges, and pheasants range throughout all of the continental United States and the Canadian provinces. Two of the species, the northern bobwhite and ring-necked pheasant, are the most economically important of all North American upland game birds. All of the species are hunted extensively for sport and are highly …


Family Living Sets The Stage For Cooperative Breeding And Ecological Resilience In Birds, Michael Griesser, Szymon M. Drobniak, Shinichi Nakagawa, Carlos A. Botero Jun 2017

Family Living Sets The Stage For Cooperative Breeding And Ecological Resilience In Birds, Michael Griesser, Szymon M. Drobniak, Shinichi Nakagawa, Carlos A. Botero

Biology Faculty Publications & Presentations

Cooperative breeding is an extreme form of cooperation that evolved in a range of lineages, including arthropods, fish, birds, and mammals. Although cooperative breeding in birds is widespread and well-studied, the conditions that favored its evolution are still unclear. Based on phylogenetic comparative analyses on 3,005 bird species, we demonstrate here that family living acted as an essential stepping stone in the evolution of cooperative breeding in the vast majority of species. First, families formed by prolonging parent–offspring associations beyond nutritional independency, and second, retained offspring began helping at the nest. These findings suggest that assessment of the conditions that …


Examining Movement And Habitat Selection Of Everglades Fishes In Response To Seasonal Water Levels, Gregory J. Hill Mar 2017

Examining Movement And Habitat Selection Of Everglades Fishes In Response To Seasonal Water Levels, Gregory J. Hill

FIU Electronic Theses and Dissertations

Fish distribution patterns and seasonal habitat use play a key role in the food web dynamics of aquatic ecosystems, including the Florida Everglades. In this study I examined the fine scale habitat shifts and movements of spotted sunfish, Lepomis punctatus across varying seasons and hydrologic conditions using in-situ field enclosures and Passive Integrated Transponder (PIT) systems. Data on fish use of three dominant Everglades marsh habitats and activity level were recorded continuously from January to August, 2015. Fish were more active and had the highest use of higher elevation habitats when water levels rose during an experimental reversal in mid-April. …


Sandhill And Whooping Cranes, Jeb Barzen, Ken Ballinger Jan 2017

Sandhill And Whooping Cranes, Jeb Barzen, Ken Ballinger

Wildlife Damage Management Technical Series

As sandhill crane populations continue to grow in the United States, so too does crop damage, property damage to homeowners, and the risk of crane collisions with aircraft. Whooping crane populations also continue to grow, but with a global population of about 500 individuals (as of 2017), damage is rare and problems often require different solutions due to the species’ endangered status. The behavioral characteristics and habitat needs of sandhill and whooping cranes set the stage for conflict between these birds and people. Recognizing behavioral differences between territorial and non-territorial cranes greatly improves the effectiveness of any management effort.

Human-Wildlife …


The North American Geese: Their Biology And Behavior, Paul A. Johnsgard Jul 2016

The North American Geese: Their Biology And Behavior, Paul A. Johnsgard

Zea E-Books Collection

The eight currently recognized species of North American geese are part of a familiar group of birds collectively called waterfowl, all of which are smaller than swans and generally larger than ducks. They include the most popular of our aquatic gamebirds, with several million shot each year by sport hunters. Our two most abundant waterfowl, the Canada goose and snow goose, have populations collectively totaling about 15 million individuals. Like swans, the lifelong pairbonding of geese, their familial care, and prolonged social attachment to their offspring are legendary. Their seasonal migratory flights sometimes span thousands of miles, and the sight …


The North American Grouse: Their Biology And Behavior, Paul A. Johnsgard Jun 2016

The North American Grouse: Their Biology And Behavior, Paul A. Johnsgard

Zea E-Books Collection

The ten currently recognized species of grouse in North America have played an important role in America’s history, from the famous but ill-fated heath hen, a primary source of meat for the earliest New England immigrants, to the ruffed grouse, currently one of the most abundant and soughtafter upland game birds in more than 40 states and provinces. This book summarizes the ecology, reproductive biology, and social behavior of all ten of the extant North American grouse species. It also describes the current status of grouse populations, some of which are perilously close to extinction. The social behavior of grouse …


Animal Mourning: Précis Of How Animals Grieve (King 2013), Barbara J. King Jan 2016

Animal Mourning: Précis Of How Animals Grieve (King 2013), Barbara J. King

Animal Sentience

Abstract: When an animal dies, that individual’s mate, relatives, or friends may express grief. Changes in the survivor’s patterns of social behavior, eating, sleeping, and/or of expression of affect are the key criteria for defining grief. Based on this understanding of grief, it is not only big-brained mammals like elephants, apes, and cetaceans who can be said to mourn, but also a wide variety of other animals, including domestic companions like cats, dogs, and rabbits; horses and farm animals; and some birds. With keen attention placed on seeking where grief is found to occur and where it is absent …


El Niño-Southern Oscillation Is Linked To Decreased Energetic Condition In Long-Distance Migrants, Kristina Paxton, Emily B. Cohen, Zoltán Németh, Frank R. Moore May 2014

El Niño-Southern Oscillation Is Linked To Decreased Energetic Condition In Long-Distance Migrants, Kristina Paxton, Emily B. Cohen, Zoltán Németh, Frank R. Moore

Faculty Publications

Predicting how migratory animals respond to changing climatic conditions requires knowledge of how climatic events affect each phase of the annual cycle and how those effects carry-over to subsequent phases. We utilized a 17-year migration dataset to examine how El Niño-Southern Oscillation climatic events in geographically different regions of the Western hemisphere carry-over to impact the stopover biology of several intercontinental migratory bird species. We found that migratory birds that over-wintered in South America experienced significantly drier environments during El Niño years, as reflected by reduced Normalized Difference Vegetation Index (NDVI) values, and arrived at stopover sites in reduced energetic …


Cognitive Representation In Transitive Inference: A Comparison Of Four Corvid Species, Alan B. Bond, Cynthia A. Wei, Alan C. Kamil May 2013

Cognitive Representation In Transitive Inference: A Comparison Of Four Corvid Species, Alan B. Bond, Cynthia A. Wei, Alan C. Kamil

Alan B. Bond

During operant transitive inference experiments, subjects are trained on adjacent stimulus pairs in an implicit linear hierarchy in which responses to higher ranked stimuli are rewarded. Two contrasting forms of cognitive representation are often used to explain resulting choice behavior. Associative representation is based on memory for the reward history of each stimulus. Relational representation depends on memory for the context in which stimuli have been presented. Natural history characteristics that require accurate configural memory, such as social complexity or reliance on cached food, should tend to promote greater use of relational representation. To test this hypothesis, four corvid species …


Patterns Of Incubation Behavior In Northern Bobwhites (Colinus Virginianus), Jonathan S. Burnam, Gretchen Turner, Susan Ellis-Felege, William E. Palmer, D. Clay Sisson, John P. Carroll Jan 2012

Patterns Of Incubation Behavior In Northern Bobwhites (Colinus Virginianus), Jonathan S. Burnam, Gretchen Turner, Susan Ellis-Felege, William E. Palmer, D. Clay Sisson, John P. Carroll

School of Natural Resources: Faculty Publications

Patterns of incubation and nesting behavior for many species of birds, especially those with cryptic nests, have been difficult to obtain due to logistical and technological limitations. As a result, little is known about the daily attendance rhythms and behavioral patterns of many species, including the Northern Bobwhite (Colinus virginianus), despite this species being one of the most studied birds in the world. Incubation represents parental investment in offspring, and a multitude of factors may affect investment behaviors, including reproductive ecology, sex and age of parent, habitat quality, clutch age, and timing in the nesting season. Most Northern Bobwhite nests …


Left-Sided Directional Bias Of Cloacal Contacts During House Sparrow Copulations, Karen Nyland, Michael Lombardo, Patrick Thorpe Jul 2010

Left-Sided Directional Bias Of Cloacal Contacts During House Sparrow Copulations, Karen Nyland, Michael Lombardo, Patrick Thorpe

Michael P Lombardo

Most female birds have only a left ovary and associated oviduct. The entry to the oviduct is on the left side of the urodeum of the cloaca. This arrangement may favor males that mount females from the left during copulation if it results in sperm being placed closer to the opening of the oviduct. Therefore, we predicted a left-sided directional bias of cloacal contacts during House Sparrow (Passer domesticus) copulations. Cloacal contacts from the left outnumbered those from the right 74 to 25 (3:1) during 25 bouts of copulation at 11 House Sparrow nests. While this pattern suggests that a …


Homosexual Copulations By Male Tree Swallows, Michael P. Lombardo, Ruth M. Bosman, Christine A. Faro, Stephen G. Houtteman, Timothy S. Kluisza Jul 2010

Homosexual Copulations By Male Tree Swallows, Michael P. Lombardo, Ruth M. Bosman, Christine A. Faro, Stephen G. Houtteman, Timothy S. Kluisza

Michael P Lombardo

Homosexual courtship behavior in non-human animals is well known (Ford and Beach 1980) and occurs in a wide variety of taxa. However, homosexual copulations, especially between males, are less well known. In birds, males mounting other males have been observed in the colonially breeding Cattle Egret (Bubulcus ibis) (Fujioka and Yamagishi 1981) and Common Murre (Uria aalge) (Birkhead et al. 1985, Hatchwell 1988). Neither Fujioka and Yamagishi (1981) nor Birkhead et al. (1985) and Hatchwell (1988) reported whether cloacal contact occurred during their observations of male-male mountings. Here we describe homosexual copulations by male Tree Swallows …


Within-Pair Copulations: Are Female Tree Swallows Feathering Their Own Nests?, Michael Lombardo Jul 2010

Within-Pair Copulations: Are Female Tree Swallows Feathering Their Own Nests?, Michael Lombardo

Michael P Lombardo

A variety of hypotheses has been proposed to explain why socially monogamous birds copulate repeatedly with their mates when only a single copulation is necessary to fertilize an entire clutch (Birkhead and Møller 1992, Petrie 1992, Hunter et al. 1993). Petrie (1992) hypothesized that a female should copulate frequently with her mate so as to reduce her mate’s involvement in extrapair copulations. By reducing her mate’s involvement in extrapair copulations, a female may: (1) avoid the transmission of parasites and sexually transmitted diseases (Hamilton 1990); (2) may avoid sperm depletion by her mate; and (3) may monopolize her mate’s paternal …


Left-Sided Directional Bias Of Cloacal Contacts During Tree Swallow Copulations, Aaron Petersen, Michael Lombardo, Harry Power Jul 2010

Left-Sided Directional Bias Of Cloacal Contacts During Tree Swallow Copulations, Aaron Petersen, Michael Lombardo, Harry Power

Michael P Lombardo

Most female birds have only a left ovary and associated oviduct with entry to the oviduct on the left side of the urodeum of the cloaca. We hypothesized that male cloacal contacts during copulation would occur from the left side of females because this would put sperm closer to the entrance of the oviduct. We observed that cloacal contacts from the left outnumbered those from the right by a margin of 3:1 during tree swallow, Tachycineta bicolor, copulations at nestboxes in western Michigan in 1999. The directional bias of cloacal contacts may have an adaptive function.


Cognitive Representation In Transitive Inference: A Comparison Of Four Corvid Species, Alan B. Bond, Cynthia A. Wei, Alan C. Kamil Jan 2010

Cognitive Representation In Transitive Inference: A Comparison Of Four Corvid Species, Alan B. Bond, Cynthia A. Wei, Alan C. Kamil

Alan Bond Publications

During operant transitive inference experiments, subjects are trained on adjacent stimulus pairs in an implicit linear hierarchy in which responses to higher ranked stimuli are rewarded. Two contrasting forms of cognitive representation are often used to explain resulting choice behavior. Associative representation is based on memory for the reward history of each stimulus. Relational representation depends on memory for the context in which stimuli have been presented. Natural history characteristics that require accurate configural memory, such as social complexity or reliance on cached food, should tend to promote greater use of relational representation. To test this hypothesis, four corvid species …


How Birds Combat Ectoparasites, Dale H. Clayton, Jennifer A. H. Koop, Christopher W. Harbison, Brett R. Moyer, Sarah E. Bush Jan 2010

How Birds Combat Ectoparasites, Dale H. Clayton, Jennifer A. H. Koop, Christopher W. Harbison, Brett R. Moyer, Sarah E. Bush

Harold W. Manter Laboratory: Library Materials

Birds are plagued by an impressive diversity of ectoparasites, ranging from feather-feeding lice, to feather-degrading bacteria. Many of these ectoparasites have severe negative effects on host fitness. It is therefore not surprising that selection on birds has favored a variety of possible adaptations for dealing with ectoparasites. The functional significance of some of these defenses has been well documented. Others have barely been studied, much less tested rigorously. In this article we review the evidence--or lack thereof--for many of the purported mechanisms birds have for dealing with ectoparasites. We concentrate on features of the plumage and its components, as well …


Left-Sided Directional Bias Of Cloacal Contacts During House Sparrow Copulations, Karen B. Nyland, Michael P. Lombardo, Patrick A. Thorpe Dec 2003

Left-Sided Directional Bias Of Cloacal Contacts During House Sparrow Copulations, Karen B. Nyland, Michael P. Lombardo, Patrick A. Thorpe

Peer Reviewed Publications

Most female birds have only a left ovary and associated oviduct. The entry to the oviduct is on the left side of the urodeum of the cloaca. This arrangement may favor males that mount females from the left during copulation if it results in sperm being placed closer to the opening of the oviduct. Therefore, we predicted a left-sided directional bias of cloacal contacts during House Sparrow (Passer domesticus) copulations. Cloacal contacts from the left outnumbered those from the right 74 to 25 (3:1) during 25 bouts of copulation at 11 House Sparrow nests. While this pattern suggests …


Within-Pair Copulations: Are Female Tree Swallows Feathering Their Own Nests?, Michael P. Lombardo Jan 1995

Within-Pair Copulations: Are Female Tree Swallows Feathering Their Own Nests?, Michael P. Lombardo

Peer Reviewed Publications

A variety of hypotheses has been proposed to explain why socially monogamous birds copulate repeatedly with their mates when only a single copulation is necessary to fertilize an entire clutch (Birkhead and Møller 1992, Petrie 1992, Hunter et al. 1993). Petrie (1992) hypothesized that a female should copulate frequently with her mate so as to reduce her mate’s involvement in extrapair copulations. By reducing her mate’s involvement in extrapair copulations, a female may: (1) avoid the transmission of parasites and sexually transmitted diseases (Hamilton 1990); (2) may avoid sperm depletion by her mate; and (3) may monopolize her mate’s paternal …


Homosexual Copulations By Male Tree Swallows, Michael P. Lombardo, Ruth M. Bosman, Christine A. Faro, Stephen G. Houtteman, Timothy S. Kluisza Jan 1994

Homosexual Copulations By Male Tree Swallows, Michael P. Lombardo, Ruth M. Bosman, Christine A. Faro, Stephen G. Houtteman, Timothy S. Kluisza

Peer Reviewed Publications

Homosexual courtship behavior in non-human animals is well known (Ford and Beach 1980) and occurs in a wide variety of taxa. However, homosexual copulations, especially between males, are less well known. In birds, males mounting other males have been observed in the colonially breeding Cattle Egret (Bubulcus ibis) (Fujioka and Yamagishi 1981) and Common Murre (Uria aalge) (Birkhead et al. 1985, Hatchwell 1988). Neither Fujioka and Yamagishi (1981) nor Birkhead et al. (1985) and Hatchwell (1988) reported whether cloacal contact occurred during their observations of male-male mountings. Here we describe homosexual copulations by male Tree Swallows …