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Estimating Nests Not Present At The Time Of Breeding Surveys: An Important Consideration In Assessing Nesting Populations, Peter C. Frederick, Julie A. Heath, Robert Bennetts, Heinz Hafner
Estimating Nests Not Present At The Time Of Breeding Surveys: An Important Consideration In Assessing Nesting Populations, Peter C. Frederick, Julie A. Heath, Robert Bennetts, Heinz Hafner
Julie Heath
Counts of nest starts are often used as indicators of the size of avian nesting populations, or of avian productivity. However, the accuracy of single or repeated counts of unmarked nests over time for estimating seasonal numbers of nests may be strongly affected by nest events that fall in between survey dates, or that occurred prior to or after the survey period. Accuracy may also be affected by uncertainty in the interpretation of counts due to overlap between starting and ending dates of asynchronous nests during the intervisit interval. To measure the combined magnitude of these effects on survey accuracy, …
Reproductive Physiology Of Free-Living White Ibises (Eudocimus Albus) In The Florida Everglades, Julie A. Heath, Peter C. Frederick, Thea M. Edwards, Louis J. Guillette Jr.
Reproductive Physiology Of Free-Living White Ibises (Eudocimus Albus) In The Florida Everglades, Julie A. Heath, Peter C. Frederick, Thea M. Edwards, Louis J. Guillette Jr.
Julie Heath
We measured plasma concentrations of testosterone, estradiol, progesterone, and corticosterone; and recorded changes in gonad size, body condition, molt, and brood patch development of free-living adult White Ibises (Eudocimus albus) during the breeding season in the Florida Everglades. White Ibises are colonially breeding, long-legged wading birds that inhabit freshwater and estuarine wetlands. They have flexible breeding schedules (nest initiation dates can range from January to September) and onset of nesting is usually associated with increased prey availability caused by concentration of small fish in pools during periods of wetland drying. In this paper, we present the hormonal and physical characteristics …
Estimating The Latitudinal Origins Of Migratory Birds Using Hydrogen And Sulfur Stable Isotopes In Feathers: Influence Of Marine Prey Base, Casey A. Lott, Timothy D. Meehan, Julie A. Heath
Estimating The Latitudinal Origins Of Migratory Birds Using Hydrogen And Sulfur Stable Isotopes In Feathers: Influence Of Marine Prey Base, Casey A. Lott, Timothy D. Meehan, Julie A. Heath
Julie Heath
Hydrogen stable isotope analysis of feathers is an important tool for estimating the natal or breeding latitudes of nearctic-neotropical migratory birds. This method is based on the latitudinal variation of hydrogen stable isotope ratios in precipitation in North America (iDp) and the inheritance of this variation in newly formed feathers (iDf). We hypothesized that the typically strong relationship between iDp and iDf would be decoupled in birds that forage in marine food webs because marine waters have relatively high iD values compared to iD values for local precipitation. Birds that forage on marine prey bases should also have feathers with …