Breeding Patterns of Henslow's Sparrow and Sympatric Grassland Sparrow Species

摘要: Abstract Henslow's Sparrows (Ammodramus henslowii) are reported to have irregular patterns of return breeding areas. I present data supporting these reports at rangewide extents, while testing potential biases inherent in the North American Breeding Bird Survey data. Two measures population variability were used show that less likely use areas predictably and consistently, but similar variance numbers occupied sites relative other sympatric grassland sparrow species. illustrate how restricting analyses single-observer-collected results subtle significant effects not detected aggregated from multiple observers through study period. The most conservative analysis (single-observer, restricted distribution) showed exhibited lower prevalence occurrence than Grasshopper savannarum) (P < 0.001) Savannah (Passerculus sandwichensis) sparrows no diffe...