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Full-Text Articles in Ornithology
Intraspecific Intrusion At Bald Eagle Nests, Courtney Turrin, B. D. Watts
Intraspecific Intrusion At Bald Eagle Nests, Courtney Turrin, B. D. Watts
Arts & Sciences Articles
Competition for nesting territory has been shown to act as a density-dependent feedback mechanism influencing population growth rate. However, little is known about the nature of territorial interactions between established breeders and floaters. We examined territorial intrusion rates and associated behaviours at active Bald Eagle Haliaeetus leucocephalus nests in the lower Chesapeake Bay in 2012 and 2013. The average intrusion rate experienced at study nests during the reproductive period was 0.28 ± 0.32 intrusions/h. Variance in intrusion rate was high and there was no apparent predictive pattern to these events. Juvenile intrusions occurred closer to the nest than adult intrusions, …
Mercury Reduces Avian Reproductive Success And Imposes Selection: An Experimental Study With Adult- Or Lifetime-Exposure In Zebra Finch, Claire W. Varian-Ramos, John P. Swaddle, Daniel A. Cristol
Mercury Reduces Avian Reproductive Success And Imposes Selection: An Experimental Study With Adult- Or Lifetime-Exposure In Zebra Finch, Claire W. Varian-Ramos, John P. Swaddle, Daniel A. Cristol
Arts & Sciences Articles
Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. …
Recovery Of Breeding Bald Eagles On Aberdeen Proving Ground, B. D. Watts
Recovery Of Breeding Bald Eagles On Aberdeen Proving Ground, B. D. Watts
Arts & Sciences Articles
We conducted annual aerial surveys (1991-2011) for breeding Bald Eagles (Haliaeetus leucocephalus) within Aberdeen Proving Ground (APG), a 350-km2 military installation located along the northwestern shoreline of the upper Chesapeake Bay in Maryland. The population increased exponentially from 1 pair in 1977 to 58 pairs in 2011 with an average doubling time of 5.8 years. This rate was higher than that documented for the broader Chesapeake Bay and is comparable to the highest reported throughout the species range. Annual population increase was highly variable and exhibited no indication of any systematic decline. A total of 646 chicks were produced from …