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Articles 1 - 30 of 36
Full-Text Articles in Life Sciences
The Distribution And Reproductive Success Of The Western Snowy Plover Along The Central And Southern Oregon Coast - 2023, David J. Lauten, Kathleen A. Castelein, Mary Lee, Jacey Corrente, Marty R. Mccamant, Eleanor P. Gaines
The Distribution And Reproductive Success Of The Western Snowy Plover Along The Central And Southern Oregon Coast - 2023, David J. Lauten, Kathleen A. Castelein, Mary Lee, Jacey Corrente, Marty R. Mccamant, Eleanor P. Gaines
Institute for Natural Resources Publications
We monitored the distribution, abundance and productivity of the federally threatened Western Snowy Plover (Anarhynchus nivosus nivosus) along the central and south coast of Oregon from 4 April – 15 September 2023. We surveyed and monitored plover activity in a project area that included, from north to south, Sutton Beach, Siltcoos River estuary, the Dunes Overlook, North Tahkenitch Creek, Tenmile Creek, Coos Bay North Spit, Bandon Snowy Plover Management Area, New River Habitat Restoration Area (HRA) and adjacent lands, and Floras Lake. Our objectives for the project area in 2023 were to: 1) estimate the size of the adult Snowy …
The Distribution And Reproductive Success Of The Western Snowy Plover Along The Oregon Coast - 2022, David J. Lauten, Kathleen A. Castelein, Daniel Farrar, Mary Lee, Eleanor P. Gaines
The Distribution And Reproductive Success Of The Western Snowy Plover Along The Oregon Coast - 2022, David J. Lauten, Kathleen A. Castelein, Daniel Farrar, Mary Lee, Eleanor P. Gaines
Institute for Natural Resources Publications
We monitored the distribution, abundance and productivity of the federally threatened Western Snowy Plover (Charadrius nivosus nivosus) along the central and south coast of Oregon from 1 April – 15 September 2022. We surveyed and monitored plover activity in a project area that included, from north to south, Sutton Beach, Siltcoos River estuary, the Dunes Overlook, North Tahkenitch Creek, Tenmile Creek, Coos Bay North Spit, Bandon Snowy Plover Management Area, New River Habitat Restoration Area (HRA) and adjacent lands, and Floras Lake. Our objectives for the project area in 2022 were to: 1) estimate the size of the adult Snowy …
Inter- And Intracontinental Migration By The Eastern Kingbird (Tyrannus Tyrannus), Daniel H. Kim, Lucas J. Redmond, James R. Fox, Michael T. Murphy
Inter- And Intracontinental Migration By The Eastern Kingbird (Tyrannus Tyrannus), Daniel H. Kim, Lucas J. Redmond, James R. Fox, Michael T. Murphy
Biology Faculty Publications and Presentations
We recovered 12 archival geolocators deployed on Eastern Kingbirds (Tyrannus tyrannus) breeding in New York (NY; n¼3, 2 with 2 years of data), Nebraska (NE; n¼6, 1 with 2 years of data), and Oregon (OR; n¼3) to describe migratory routes, timing and rates of migration, nonbreeding season distributions, and migratory connectedness. NY fall migrants migrated along the Atlantic coast to Florida, flew either nonstop across the Gulf of Mexico (GoM; 2 of 3 birds) or stopped once along the way (Cuba and Cayman Islands in different years) to land in Yucatan/Central America. Fall birds from NE and OR arrived at …
Effects Of Management For Productivity On Adult Survival Of Snowy Plovers, Eleanor P. Gaines, Stephen J. Dinsmore, Michael T. Murphy
Effects Of Management For Productivity On Adult Survival Of Snowy Plovers, Eleanor P. Gaines, Stephen J. Dinsmore, Michael T. Murphy
Biology Faculty Publications and Presentations
Understanding the factors contributing to variation in demographic parameters and their influences on population growth is fundamental to effective conservation of small populations, but this information is often not available. Among shorebirds, population growth is generally most sensitive to changes in adult survival so understanding the factors affecting this vital rate is important. We used a long‐term mark–resight dataset and Program MARK to examine the effect of management actions, initiated to improve nesting productivity, on adult survival in a threatened population of Snowy Plovers (Charadrius nivosus ) in Oregon, USA. Apparent adult survival averaged 0.71 ± 0.01 (SE), but …
Follow The Rain? Environmental Drivers Of Tyrannus Migration Across The New World, Maggie P. Macpherson, Alex E. Jahn, Michael T. Murphy, Daniel H. Kim, Victor R. Cueto, Diego T. Tuero, Elliot D. Hill
Follow The Rain? Environmental Drivers Of Tyrannus Migration Across The New World, Maggie P. Macpherson, Alex E. Jahn, Michael T. Murphy, Daniel H. Kim, Victor R. Cueto, Diego T. Tuero, Elliot D. Hill
Biology Faculty Publications and Presentations
Predictable seasonal changes in resources are thought to drive the timing of annual animal migrations; however, we currently understand little about which environmental cues or resources are tracked by different migratory bird species across the planet. Understanding which environmental cues or resources birds track in multiple migratory systems is a prerequisite to developing generalizable conservation plans for migratory birds in a changing global environment. Within the New World, climatic differences experienced by Nearctic–Neotropical migratory (NNM; i.e. breed in North America and spend the nonbreeding period in the Neotropics) and Neotropical austral migratory (NAM; i.e. breed and spend the nonbreeding period …
Winter Diet Of Bobolink, A Long-Distance Migratory Grassland Bird, Inferred From Feather Isotopes, Rosalind B. Renfrew, Jason M. Hill, Daniel H. Kim, Christopher Romanek, Noah G. Perlut
Winter Diet Of Bobolink, A Long-Distance Migratory Grassland Bird, Inferred From Feather Isotopes, Rosalind B. Renfrew, Jason M. Hill, Daniel H. Kim, Christopher Romanek, Noah G. Perlut
Biology Faculty Publications and Presentations
Effective conservation of migratory bird populations depends on advancements in our understanding of processes throughout the life cycle. Fundamental information about wintering ecology (e.g., habitat use and diet composition) remains limited, which limits assessment of threats to populations during winter. Bobolink (Dolichonyx oryzivorus) is a year-round grassland obligate and Nearctic-Neotropical migrant that undergoes 2 complete molts each year, including a complete prealternate molt on the South American wintering grounds. This unusual winter molt provides a rare opportunity to examine, using stable isotope analysis, the timing and contribution of foraging resources in the Bobolink diet prior to northbound migration from disparate …
Factors Affecting Snowy Plover Chick Survival In A Managed Population, Stephen J. Dinsmore, Eleanor P. Gaines, Scott F. Pearson, David J. Lauten, Kathleen J. Castelein
Factors Affecting Snowy Plover Chick Survival In A Managed Population, Stephen J. Dinsmore, Eleanor P. Gaines, Scott F. Pearson, David J. Lauten, Kathleen J. Castelein
Institute for Natural Resources Publications
Understanding survival of precocial chicks in the period immediately following hatching has important conservation implications because population growth is often sensitive to post-hatching survival. We studied federally threatened Western Snowy Plover (Charadrius nivosus nivosus) broods at the northern limit of their range in coastal Oregon (n ¼ 1,157) and Washington (n ¼ 84) from 1991 to 2011 in an attempt to understand seasonal, annual, and spatial patterns of chick survival. In Oregon, plover chick survival increased with age, varied between sites, and was greater at sites with predator management. The mean probability of surviving from hatch to fledging at 28 …
Empirical Evidence For The Scale Dependence Of Biotic Interactions, Jonathan Belmaker, Phoebe Zarnetske, Sara Zonneveld, Sydne Record, Angela L. Strecker, Lydia Beaudrot
Empirical Evidence For The Scale Dependence Of Biotic Interactions, Jonathan Belmaker, Phoebe Zarnetske, Sara Zonneveld, Sydne Record, Angela L. Strecker, Lydia Beaudrot
Environmental Science and Management Faculty Publications and Presentations
Aim: Although it is recognized that ecological patterns are scale dependent, the exact scales over which specific ecological processes operate are still a matter of controversy. In particular, understanding the scales over which biotic interactions operate is critical for predicting changes in species distributions in the face of the ongoing biodiversity crisis. It has been hypothesized that biotic interactions operate predominately at fine grains, yet this conjecture has received relatively little empirical scrutiny. We use US woodpeckers as a model system to assess the relative importance of biotic interactions, environmental suitability and geographic proximity to other intraspecific occurrence sites, …
Experimental Analysis Of Nest-Site Choice And Its Relationship To Nest Success In An Open-Cup–Nesting Passerine, Sarah Cancellieri, Michael T. Murphy
Experimental Analysis Of Nest-Site Choice And Its Relationship To Nest Success In An Open-Cup–Nesting Passerine, Sarah Cancellieri, Michael T. Murphy
Biology Faculty Publications and Presentations
Nest placement presumably reflects selection for secure sites to minimize failure. Most tests of this hypothesis, however, have failed to support it. We used artificial nests (ARTs) to experimentally evaluate nest-site-choice behavior by an open-cup–nesting bird, the Eastern Kingbird (Tyrannus tyrannus). In 2010 and 2011, we placed ARTs in trees in the riparian zone at Malheur National Wildlife Refuge, Oregon, USA, to test whether (1) characteristics describing the physical location in trees of used and unused ARTs differed, (2) used ART sites more closely resembled naturally chosen sites, (3) successful natural nests (NATs) and successful ARTs were similarly …
Residential Edges As Ecological Traps: Postfledgling Survival Of A Ground-Nesting Passerine In A Forested Urban Park, Amy A. Shipley, Michael T. Murphy, Adam H. Elzinga
Residential Edges As Ecological Traps: Postfledgling Survival Of A Ground-Nesting Passerine In A Forested Urban Park, Amy A. Shipley, Michael T. Murphy, Adam H. Elzinga
Biology Faculty Publications and Presentations
Substantial offspring mortality can occur during the postfledging period of birds, but few postfledging survival studies have been conducted within the context of habitat suitability. We conducted a 2-year radiotelemetry study of Spotted Towhee (Pipilo maculatus) reproductive success and fledgling survival in a 24-ha forested park in a residential area of Lake Oswego, Oregon. In corroboration of previous research on this species, we found (1) that Spotted Towhees nested closer to the edge between the park and residential neighborhoods than expected by chance, and (2) that pairs nesting near edges produced the largest and most offspring. However, fates were reversed …
Migration Timing And Wintering Areas Of Three Species Of Flycatchers (Tyrannus) Breeding In The Great Plains Of North America, Alex E. Jahn, Victor R. Cueto, James W. Fox, Michael S. Husak, Daniel H. Kim, Diane V. Landoll, Jesús Pinto Ledezma, Heather K. Lepage, Douglas J. Levey, Michael T. Murphy, Rosalind B. Renfrew
Migration Timing And Wintering Areas Of Three Species Of Flycatchers (Tyrannus) Breeding In The Great Plains Of North America, Alex E. Jahn, Victor R. Cueto, James W. Fox, Michael S. Husak, Daniel H. Kim, Diane V. Landoll, Jesús Pinto Ledezma, Heather K. Lepage, Douglas J. Levey, Michael T. Murphy, Rosalind B. Renfrew
Biology Faculty Publications and Presentations
Descriptions of intra- and interspecific variation in migratory patterns of closely related species are rare yet valuable because they can help assess how differences in ecology and life-history strategies drive the evolution of migration. We report data on timing and location of migration routes and wintering areas, and on migratory speed and phenology, of Eastern Kingbirds (Tyrannus tyrannus) from Nebraska and Oklahoma and of Western Kingbirds (T. verticalis) and Scissor-tailed Flycatchers (T. forficatus) from Oklahoma. Eastern Kingbirds primarily departed the breeding site in September, migrating to the Amazon Basin (Bolivia and Brazil), >6,400 km …
An Experimental Investigation Of Nest Reuse And Nest Site Selection In An Open-Cup Nesting Passerine, Sarah A. Cancellieri
An Experimental Investigation Of Nest Reuse And Nest Site Selection In An Open-Cup Nesting Passerine, Sarah A. Cancellieri
Dissertations and Theses
Eastern Kingbirds (Tyrannus tyrannus) breed from coast to coast in North America and build open-cup nests in trees. They have been extensively studied across most of their range and have only on occasion been documented to reuse a nest from a previous season. However, at Malheur National Wildlife Refuge (MNWR), located in southeastern Oregon, ~10 % of female Eastern Kingbirds reuse old nests of mainly American Robins (Turdus migratorius). In an attempt to address why nest reuse is so common at MNWR, I used artificial nests to evaluate two hypotheses as to why nest reuse is common in this breeding …
Site Selection By Migratory Shorebirds In Oregon Estuaries Over Broad And Fine Spatial Scales, Aileen Kilpatrick Miller
Site Selection By Migratory Shorebirds In Oregon Estuaries Over Broad And Fine Spatial Scales, Aileen Kilpatrick Miller
Dissertations and Theses
Many migratory shorebirds rely on estuaries as stop-over sites to refuel during migration, and the loss of stop-over sites is a primary threat to shorebird populations on the West Coast of the United States (e.g. Calidris alpina pacifica, C. mauri). Conservation and research has focused on the largest of these sites; however, smaller estuaries also host thousands of migratory shorebirds. Furthermore, the reasons for site selection are largely unknown. Estuarine inter-tidal microhabitats are non-uniform and both abiotic and biotic factors may serve as predictors of whether an abundance of shorebirds will use a site. I investigated shorebird site selection on …
The Breeding Biology Of The Northern Pygmy Owl: Do The Smallest Of The Small Have An Advantage?, John F. Deshler, Michael T. Murphy
The Breeding Biology Of The Northern Pygmy Owl: Do The Smallest Of The Small Have An Advantage?, John F. Deshler, Michael T. Murphy
Biology Faculty Publications and Presentations
We explored the breeding biology of the Northern Pygmy-Owl (Glaucidium gnoma) from 2007 to 2009 in a forested reserve in Portland, Oregon. Large body size is often assumed to give animals reproductive advantages, and we tested whether body size affected timing of breeding and examined variation in diet, breeding date, clutch size, and reproductive success to explore whether the presumed benefits of large body size are evident in this species. The average size of 13 clutches was 5.8, and nest success was high (92%); 22 successful nests fledged an average of 5.2 young. Dates of first laying varied …
Multistate Mark-Recapture Analysis Reveals No Effect Of Blood Sampling On Survival And Recapture Of Eastern Kingbirds (Tyrannus Tyrannus), Lucas J. Redmond, Michael T. Murphy
Multistate Mark-Recapture Analysis Reveals No Effect Of Blood Sampling On Survival And Recapture Of Eastern Kingbirds (Tyrannus Tyrannus), Lucas J. Redmond, Michael T. Murphy
Biology Faculty Publications and Presentations
The experimentally supported and prevailing opinion is that blood sampling has few to no long-term effects on survival of birds when conducted properly, and blood sampling has become a vital addition to the toolbox of many ornithologists. However, many of the studies that concluded that blood sampling had negligible effects on birds used approaches that did not account for temporary emigration and probability of capture. To date, the only study to have done so found that blood sampling had a strong negative effect on survival. We conducted a mark–recapture analysis of 8 years of banding and bleeding data on Eastern …
Fecal-Sac Ingestion By Spotted Towhees, Jenny E. Mckay, Michael T. Murphy, Sarah Bartos Smith, Jennifer K. Richardson
Fecal-Sac Ingestion By Spotted Towhees, Jenny E. Mckay, Michael T. Murphy, Sarah Bartos Smith, Jennifer K. Richardson
Biology Faculty Publications and Presentations
Altricial nestlings encase excrement in fecal sacs that parents remove by either ingesting them or transporting them away from the nest. Ingestion may allow energetically or nutritionally deprived parents to recapture energy or nutrients that might be lost because of nestlings' inefficient digestion (the "parental-nutrition hypothesis"), but ingestion may also permit parents to avoid flights from the nest that interfere with parental care (e.g., brooding young; the "economic-disposal hypothesis"). We used a hypothetico-deductive approach to test the two hypotheses' ability to account for fecal-sac ingestion by the Spotted Towhee (Pipilo maculatus). We confirmed the parental-nutrition hypothesis' predictions that …
Lifetime Reproductive Success Of Female Eastern Kingbirds (Tyrannus Tyrannus): Influence Of Lifespan, Nest Predation And Body Size, Michael T. Murphy
Lifetime Reproductive Success Of Female Eastern Kingbirds (Tyrannus Tyrannus): Influence Of Lifespan, Nest Predation And Body Size, Michael T. Murphy
Biology Faculty Publications and Presentations
I report on the lifetime reproductive success (LRS) of female Eastern Kingbirds (Tyrannus tyrannus) in central New York. I investigated the major correlates of LRS and specifi cally tested the hypothesis that small body size yields reproductive benefi ts. Lifetime reproductive success varied widely: 15–20% of females failed to fledge young over their life, whereas 50% of young were fledged by 20% of females. Female lifespan varied between one and eight years, and females that died after one breeding season tended to be smaller-bodied than long-lived females (≥2 seasons). I therefore conducted analyses of LRS for the entire sample and …
A Cautionary Tale: Cryptic Sexual Size Dimorphism In A Socially Monogamous Passerine, Michael T. Murphy
A Cautionary Tale: Cryptic Sexual Size Dimorphism In A Socially Monogamous Passerine, Michael T. Murphy
Biology Faculty Publications and Presentations
Among socially monogamous birds, standard metrics suggest that males are only ∼5% larger than females. An untested assumption is that, with the exception of reproductive systems, males and females are scaled mirror images of one another. I used external morphological and skeletal data, and information on muscle mass and organ size, to test this assumption in a population of breeding Eastern Kingbirds (Tyrannus tyrannus). Male and female Eastern Kingbirds exhibited no differences in body mass or standard measures of size, except in a longer (∼6%) wing chord and tail in males. However, keel length, a character rarely measured …
Nest Reuse By Eastern Kingbirds: Adaptive Behavior Or Ecological Constraint?, Lucas J. Redmond, Michael T. Murphy, Amy C. Dolan
Nest Reuse By Eastern Kingbirds: Adaptive Behavior Or Ecological Constraint?, Lucas J. Redmond, Michael T. Murphy, Amy C. Dolan
Biology Faculty Publications and Presentations
The reuse of old nests by open-cup nesting passerines is a seemingly rare but potentially adaptive behavior if, as a consequence, females begin to breed earlier, lay larger clutches, or fledge more young. We report an unusually high rate of nest reuse (~10% of 341 nests) for Eastern Kingbirds (Tyrannus tyrannus) breeding at Malheur National Wildlife Refuge, Oregon. We found no difference in availability of nesting habitat or food abundance in territories in which nests were and were not reused. We also found no support for the hypotheses that kingbirds benefited from nest reuse by breeding earlier, laying …
Avian Population Trends Within The Evolving Agricultural Landscape Of The Eastern And Central United States, Michael T. Murphy
Avian Population Trends Within The Evolving Agricultural Landscape Of The Eastern And Central United States, Michael T. Murphy
Biology Faculty Publications and Presentations
State-level Breeding Bird Survey (1980-1998) and U.S. Department of Agriculture statistics were used to test the hypothesis that changes in agricultural land use within the eastern and central U.S. have driven population trends of grassland and shrub habitat birds over the past two decades. The degree to which population trends differed between grassland and shrub habitats was evaluated with respect to migratory and nesting behavior. Grassland birds declined significantly between 1980 and 1999, but, on average, shrub habitat species did not. Grassland-breeding, long-distance migrants exhibited the strongest negative trends. Most species (78%; n = 63) exhibited at least one significant …
High Frequency Of Extra-Pair Paternity In Eastern Kingbirds, Diane L. Rowe, Michael T. Murphy, Robert C. Fleischer, Paul G. Wolf
High Frequency Of Extra-Pair Paternity In Eastern Kingbirds, Diane L. Rowe, Michael T. Murphy, Robert C. Fleischer, Paul G. Wolf
Biology Faculty Publications and Presentations
Genetic parentage in the socially monogamous and territorial Eastern Kingbird( Tyrannust tyrannus) was examined in a central New York population by multilocus DNA fingerprinting. Extra-pair young were identified in 60% (12 of 20) of nests. Of the 64 nestlings profiled, 42% were sired by extra-pair males, but no cases of conspecific brood parasitism were detected. These results are markedly different from a previous electrophoretic study of the same species in a Michigan population, which reported 39% of nestlings were unrelated to one (typically the mother, quasiparasitismo)r both (conspecificb roodp arasitism) of the putative parents. In the New York population, extra-pairp …
Is Reproduction By Tree Swallows (Tachycineta Bicolor) Cost-Free?, Michael T. Murphy
Is Reproduction By Tree Swallows (Tachycineta Bicolor) Cost-Free?, Michael T. Murphy
Biology Faculty Publications and Presentations
We manipulated brood sizes of Tree Swallows (Tachycineta bicolor) in 1996 and 1997 to test for the existence of intra- and intergenerational costs of reproduction. Modal clutch size was six eggs, but experimental brood sizes ranged from two to nine young. Nestling starvation was higher in 1996 (and dependent on brood size) than in 1997, but in both years enlargement of brood size resulted in increased productivity. Nestling mass near fledging was negatively correlated with brood size, but tarsus length and wing chord were not. Food deliveries by parents increased steadily between broods of two to six young but then …
Breeding Patterns Of Eastern Phoebes In Kansas: Adaptive Strategies Or Physiological Constraint?, Michael T. Murphy
Breeding Patterns Of Eastern Phoebes In Kansas: Adaptive Strategies Or Physiological Constraint?, Michael T. Murphy
Biology Faculty Publications and Presentations
Data were collected on annual (1980-1983) and seasonal (spring vs. summer) variation in reproduction by the double-brooded Eastern Phoebe (Sayornis phoebe) to test the proposal that phoebes modify reproductive patterns on a seasonal basis and switch from being brood survivalists in spring to brood reductionists in summer. Clutch size did not differ between spring and summer broods nor among years, but spring nests fledged one more nestling than summer nests. In 1981 breeding began earlier, eggs were larger, and nestlings grew faster than in all other years. Clutch size and egg mass within spring clutches increased seasonally. Egg mass was …
The Impact Of Weather On Kingbird Foraging Behavior, Michael T. Murphy
The Impact Of Weather On Kingbird Foraging Behavior, Michael T. Murphy
Biology Faculty Publications and Presentations
Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats).
Body Size, Nest Predation, And Reproductive Patterns In Brown Thrashers And Other Mimids, Michael T. Murphy, Robert C. Fleischer
Body Size, Nest Predation, And Reproductive Patterns In Brown Thrashers And Other Mimids, Michael T. Murphy, Robert C. Fleischer
Biology Faculty Publications and Presentations
We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. Brown Thrashers produced clutches of 3 to 6 eggs, but clutches of 4 predominated. Most pairs raised 2 broods per year. Incubation required between 13 and 14 days, and hatching was usually asynchronous. Though sample size was small, asynchrony appeared to increase in frequency towards the end of the breeding season. Nestlings grew rapidly, and in 10 days or less most pre-fledgingg rowthw as completed. Young fledgedn ormallya t 11 days …
Body Size And Condition, Timing Of Breeding, And Aspects Of Egg Production In Eastern Kingbirds, Michael T. Murphy
Body Size And Condition, Timing Of Breeding, And Aspects Of Egg Production In Eastern Kingbirds, Michael T. Murphy
Biology Faculty Publications and Presentations
Variation in timing of breeding in Eastern Kingbirds (Tyrannus tyrannus) was correlated only weakly with external morphological characters, but was correlated positively and significantly with estimates of body size based on measurements of skeletons and muscle weights. Small females apparently held a reproductive advantage in being able to mobilize resources for reproduction before large females. Egg weight was independent of all measures of female size, but was directly and significantly (P = 0.03) correlated with standard flight muscle weight, a relative index of body condition. Egg size was thus a function more of female body condition than size. On average, …
Brood Parasitism Of Eastern Kingbirds By Brown-Headed Cowbirds, Michael T. Murphy
Brood Parasitism Of Eastern Kingbirds By Brown-Headed Cowbirds, Michael T. Murphy
Biology Faculty Publications and Presentations
Understanding why brood parasites lay eggs in the nests of hosts that reject eggs is hampered by insuf-ficient data on the frequency with which parasites lay in rejecter nests, and by ignorance of which in-dividuals practice this seemingly inappropriate be-havior. Parasitism rates of rejecters can be deter-mined only when host nests are observed during egg laying because most parasite eggs are rejected rapidly (e.g. Scott 1977). Even then, however, a certain per-centage of parasitized nests may go undetected. De-termining the selective value of host defense mech-anisms also depends on knowledge of the frequency of parasitism, and the amount of reproductive …
The Analysis And Use Of Methodologies For The Study Of The Diets Of Long-Eared Owls From Three Environments In North Central Oregon, John M. Barss
The Analysis And Use Of Methodologies For The Study Of The Diets Of Long-Eared Owls From Three Environments In North Central Oregon, John M. Barss
Dissertations and Theses
Part I of this study presents a procedure for standardization of pellet analysis methodologies which improves estimation of prey biomass and determines the number of pellets needed to estimate prey diversity indices. The procedure was developed to provide a simple, easily replicated methodology for the study of pellets which also retains maximal data recorded from pellet analysis. A sample size of ten Long-eared Owl pellets was found adequate to calculate diversity indices with no significant loss of accuracy when compared to total pellets recovered from beneath a roosting site. Analysis of the total sample of pellets from a specific roost …
Nest Success And Nesting Habits Of Eastern Kingbirds And Other Flycatchers, Michael T. Murphy
Nest Success And Nesting Habits Of Eastern Kingbirds And Other Flycatchers, Michael T. Murphy
Biology Faculty Publications and Presentations
Patterns of nest placement and its relationship to nest success in the Eastern Kingbird (Tyrannus tyrannus) were studied in populations breeding in New York and Kansas. Data were augmented with information on nest placement in other open-nesting tyrannids in order to examine the hypothesis that these flycatchers place their nests chiefly so as to conceal them from predators. Nesting success was significantly greater in New York than in Kansas but was relatively high in both populations, as is apparently true of North American breeding flycatchers in general. Geographic variation in nest placement in the Eastern Kingbird was relatively small and …
Clutch Size In The Eastern Kingbird: Factors Affecting Nestling Survival, Michael T. Murphy
Clutch Size In The Eastern Kingbird: Factors Affecting Nestling Survival, Michael T. Murphy
Biology Faculty Publications and Presentations
Observational and experimental procedures were used to evaluate the potential importance of brood size and weather on the evolution of clutch size in the Eastern Kingbird. Modal clutch size was three eggs, yet broods of four were most productive. Nestling size varied inversely with brood size, so that "nestling quality" was lower in broods of four than in broods of three. Asymptotic weight of nestlings in broods of three was directly and significantly correlated with ambient air temperature, followed by hatch order. Because larger broods were being fed during a period of relatively cool and wet weather, the effects of …