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Articles 1 - 8 of 8
Full-Text Articles in Ornithology
High Prevalence Of Leucocytozoon Parasites In Nestling Northern Goshawks (Accipiter Gentilis) In The Northern Great Basin, U.S.A., Michelle I. Jeffries, Robert A. Miller, Michelle D. Laskowski, Jay D. Carlisle
High Prevalence Of Leucocytozoon Parasites In Nestling Northern Goshawks (Accipiter Gentilis) In The Northern Great Basin, U.S.A., Michelle I. Jeffries, Robert A. Miller, Michelle D. Laskowski, Jay D. Carlisle
Robert Miller
The Northern Goshawk (Accipiter gentilis) is currently listed as a sensitive species by the U.S.D.A. Forest Service. Previous research in our study area, the South Hills of the Minidoka Ranger District of the Sawtooth National Forest, Idaho, identified possible signs of parasite infections among the banded adult and nestling goshawks, which could influence their survival and breeding success. Therefore, we sought to quantify the prevalence and intensity of Leucocytozoon parasites among a sample of nestling goshawks in the South Hills during the 2012 breeding season. We sampled 27 nestlings from 12 nests for Leucocytozoon parasites by examining blood smears. All …
Annual Variation In Autumn Migration Phenology And Energetic Condition At A Stopover Site In The Western United States, Robert A. Miller, Jay D. Carlisle, Neil Paprocki, Gregory S. Kaltenecker, Julie A. Heath
Annual Variation In Autumn Migration Phenology And Energetic Condition At A Stopover Site In The Western United States, Robert A. Miller, Jay D. Carlisle, Neil Paprocki, Gregory S. Kaltenecker, Julie A. Heath
Robert Miller
Climate change is having a dramatic effect on many migratory species. Changes in climate may lead to changes in food availability or other proximate cues that affect migratory behavior. We used 13 years (2000–2012) of data on songbird banding and raptor migration counts and captures during autumn migration in the intermountain West to evaluate whether regional temperature or precipitation or hemispheric climate indices predicted autumn migratory timing and energetic condition. We examined overall trends and evaluated the effects of diet and migratory distance on phenology and conditional responses. For the 13-year study period, no temperature, precipitation, or climate index trends …
Geographic Segregation And Evidence Of Density-Dependent Changes In Sex Ratios In An Abundant Colonial Waterbird, Brian S. Dorr, Katie C. Hanson-Dorr, Travis L. Devault, Alban Guillaumet, Scott C. Barras
Geographic Segregation And Evidence Of Density-Dependent Changes In Sex Ratios In An Abundant Colonial Waterbird, Brian S. Dorr, Katie C. Hanson-Dorr, Travis L. Devault, Alban Guillaumet, Scott C. Barras
Brian S Dorr
Demographic information, such as geographic segregation of sexes and sex ratio data, is needed to develop, model and evaluate conservation and management strategies for wildlife. A variety of physiological, behavioral and environmental factors can influence segregation of sexes and sex ratios, many of which originate with density- dependent processes. Departure from 50:50 sex ratios of double-crested cormorants (Phalacrocorax auritus) collected during control efforts in breeding and wintering areas across their eastern range of the USA were evaluated using using a Z-test as well as Stouffer’s weighted Z-tests. In addition, a specifically-designed randomization test was used to evaluate density-dependent effects on …
A Study Of Mexican Free-Tailed Bat Chirp Syllables: Bayesian Functional Mixed Modeling Of Nonstationary Time Series Data With Time-Dependent Spectra, Josue G. Martinez, Kirsten M. Bohn, Raymond J. Carroll, Jeffrey S. Morris
A Study Of Mexican Free-Tailed Bat Chirp Syllables: Bayesian Functional Mixed Modeling Of Nonstationary Time Series Data With Time-Dependent Spectra, Josue G. Martinez, Kirsten M. Bohn, Raymond J. Carroll, Jeffrey S. Morris
Jeffrey S. Morris
We describe a new approach to analyze chirp syllables of free-tailed bats from two regions of Texas in which they are predominant: Austin and College Station. Our goal is to characterize any systematic regional differences in the mating chirps and assess whether individual bats have signature chirps. The data are analyzed by modeling spectrograms of the chirps as responses in a Bayesian functional mixed model. Given the variable chirp lengths, we compute the spectrograms on a relative time scale interpretable as the relative chirp position, using a variable window overlap based on chirp length. We use 2D wavelet transforms to …
Thermal Constraints On Foraging Activity Of Adult Starlings, Larry Clark
Thermal Constraints On Foraging Activity Of Adult Starlings, Larry Clark
Larry Clark
The operative temperature of the environment was estimated for starlings using hollow, unheated taxidermic mounts. On average, adults foraging in full sun were characterized by shorter foraging bouts than those adults foraging in full shade. Simultaneous observations of air temperature, operative temperature, and the foraging duration of adults indicated that air temperature was a poor predictor of the maximum length of a foraging bout. The operative temperature of the environment was not correlated to the maximum and mean length of foraging bouts for temperatures below 31.5 ~ C, but was negatively related to maximum and mean foraging duration for values …
Use Of Nest Material As Insecticidal And Anti-Pathogenic Agents By The European Starling, Larry Clark, J Russell Mason
Use Of Nest Material As Insecticidal And Anti-Pathogenic Agents By The European Starling, Larry Clark, J Russell Mason
Larry Clark
Passerine birds that reuse nest sites face an increased parasite and pathogen load. They also are more likely to use fresh green vegetation during nest construction. The present results demonstrate that at least one passerine, the European Starling: (a) selects a small subset of available plant species for inclusion in nest material; and (b) chooses plants whose volatiles are more likely to inhibit arthropod hatching and bacterial growth relative to a random subset of available vegetation. The results also show that preferred plants possess greater numbers of mono- and sesqueterpenes at higher concentrations relative to a random subset of available …
Consequences Of Homeothermic Capacity Of Nestlings On Parental Care In The European Starling, Larry Clark
Consequences Of Homeothermic Capacity Of Nestlings On Parental Care In The European Starling, Larry Clark
Larry Clark
The homeothermic capacity of chicks varied as a function of brood size, age, and air temperature. Commitment to rooding by parents also varied as a function of brood size, age of the young brooded, and prevailing air temperature. It was experimentally determined that parents altered their brooding commitment in direct response to the achieved mean homeothermic capacity of the brood rather than energy demands of the brood per se. Because larger broods achieved a given level of homeothermic capacity earlier than smaller broods, parents spent less time brooding larger broods. This "freed" time represented an increase in potential foraging time …
Nest Site Selection By The Red-Tailed Tropicbird, Larry Clark, Robert Ricklefs, Ralph Schrieber
Nest Site Selection By The Red-Tailed Tropicbird, Larry Clark, Robert Ricklefs, Ralph Schrieber
Larry Clark
-Red-tailed Tropicbirds (Phaethon rubricauda) nest under shrubs in loosely associated groups on Christmas Island, Central Pacific Ocean. Aggressive interactions among adults at nest sites are high; yet, large areas of superficially similar habitat contain no tropicbird nests at all. We compared physiognomic features of nest sites with those of two sets of randomly generated "nest sites" by discriminant function analysis. Of those variables measured, the number of stems within a nest space and the amount of peripheral cover influenced the tropicbirds' choice of nest sites. Differences among localities existed. Areas where tropicbirds nested had shrubs with few stems and more …