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The extent to which populations fill available ecological space is critical to evaluating niche-based theories of community assembly, but habitat suitability for populations is difficult to assess. The absence of a species from areas of otherwise suitable habitat might indicate localized species-specific influences, including biological interactions with competitors, consumers or pathogens, on local population persistence., I used Bray- Curtis ordination axis scores, based on the distributions of forest birds across census plots in eastern North America, as proxies of general features of habitat suitability to predict local abundances of each species of small land bird. I then applied spatial analysis to identify significant spatial structure ( Moran's I) in residuals (positive or negative) from predicted local densities, which would indicate localized species-specific influences on population size., Fifty-eight of 79 species exhibited no significant spatial structure in residual abundances, indicating that the ordination axes reflect most of the spatial variation in environmental conditions and habitat characteristics that influence population distribution and density or that samples were too small to detect significant spatial variation. Twenty-one species exhibited significant habitat-independent spatial structure of residuals within distances of 100 km. Aggregations of residuals for these species were independently located, for the most part, and thus probably unrelated to general features of the environment that affect many species., Among factors considered as potential causes of spatial anomalies, positive density dependence ( Allee effects), intraspecific social aggregation and area sensitivity in response to forest fragmentation find little support in this analysis. Because of the species-specific nature of these clustered residuals, specialized pathogens are potential candidates to drive spatial anomalies in host abundance. [ABSTRACT FROM AUTHOR]

Populations of most North American aerial insectivores have undergone steep population declines over the past 40 years but the relative importance of factors operating on breeding, wintering, or stopover sites remains unknown. We used archival light-level geolocators to track the phenology, movements and winter locations of barn swallows (Hirdundo rustica; n = 27) from populations across North America to determine their migratory connectivity. We identified an east-west continental migratory divide for barn swallows with birds from western regions (Washington State, USA (n = 8) and Saskatchewan, Canada (n = 5)) traveling shorter distances to wintering areas ranging from Oregon to northern Colombia than eastern populations (Ontario (n = 3) and New Brunswick (n = 10), Canada) which wintered in South America south of the Amazon basin. A single swallow from a stable population in Alabama shared a similar migration route to eastern barn swallows but wintered farther north in northeast Brazil indicating a potential leap frog pattern migratory among eastern birds. Six of 9 (67%) birds from the two eastern populations and Alabama underwent a loop migration west of fall migration routes including around the Gulf of Mexico travelling a mean of 2,224 km and 722 km longer on spring migration, respectively. Longer migration distances, including the requirement to cross the Caribbean Sea and Gulf of Mexico and subsequent shorter sedentary wintering periods, may exacerbate declines for populations breeding in northeastern North America. [ABSTRACT FROM AUTHOR]

The article presents a study focusing on diurnal and nocturnal birds vocalizations at night in North America. It states that nocturnal vocalizations are reported from 30 percent of birds in North America of which over 70 percent are diurnal. This shows that nocturnal vocalizations are taxonomically widespread behavior and are not limited to nocturnal species.

"The Englishwoman in America" (1856) recounts Isabella Bird's travels to the North American continent (Canada and the United States), offering an interesting mosaic of impressions and facts about Canadian and American places and people. This essay examines how the cultural and colonial encounters during her travels question and enrich different parts of her identity, particularly as a woman and as a British citizen. At the same time, a brief examination of Bird's narrative in the broader context of nineteenth-century female travel writing and a comprehensive analysis of her account through the lenses of postcolonial and feminist theories allow for a deeper, more socially engaged interpretation of her American experience and her subtle critique of colonial relationships. As traveling has become a popular and common "occupation" in our modern society, such theoretical frameworks make it easier for contemporary readers to identify with Bird's reflections on cultural encounters, relationships, and conflicts. Therefore, her desire to transgress literal and figurative borders, as well as the process of negotiation of physical and cultural spaces with a view to discovering new facets of her identity, bring her closer to the modern, more globalized audience. [ABSTRACT FROM AUTHOR]

Barred Owls (Strix varia) expanded their range to include western North America and have been competing with federally threatened Northern Spotted Owls (S. occidentalis caurina) for the past few decades. To help protect Spotted Owls, the US Fish and Wildlife Service is considering conducting a 3- to 10-y study in which as many as 2150 to 4650 Barred Owls would be killed and, possibly, conducting long-term management of Barred Owls. To help give these considerations a global perspective, I gathered information concerning instances of negative effects between native (non-introduced) birds worldwide (n = 194) and how managers address these effects. I found reports for 15 species of native birds of concern negatively affected by hybridization, 22 by brood parasitism, 58 by competition, and 99 by predation. Control commonly is used to address brood parasitism by cowbirds (Molothrus spp.), and predation by gulls (Larinae) and corvids (Corvidae), whereas control rarely is used to address competition and is never used to address hybridization. Globally, very few raptors are killed for any of these threats. If the precedent-setting removal study as described here is implemented, it would, during its 1st year, result in the death of 36 times more raptors than in all other conservation-based projects combined in the United States and its territories, and 84 times more raptors than in the largest ongoing effort worldwide. This study could cost $1 million annually; simplifying the cost to dollars per Barred Owl killed approximates $700 per Barred Owl for the 1st year and $2800 per Barred Owl for each subsequent year [ABSTRACT FROM AUTHOR]

This paper follows some photographs produced by Edward Curtis from his fieldwork in northwest Alaska in the summer of 1927. Inspired by Deborah Poole's work on the circulation of image-objects, it offers an account of their production and changing appeal in the United States. What makes these particular prints interesting is the contemporary work that they facilitate in northwest Alaska, in a hotel built in the vicinity of the sites where these images were first taken. What difference does their lodging in that context make? What sorts of subjects and subjectivities do they cultivate there? How can these image-objects in the hotel be looked at differently? In responding, it is suggested that these particular prints recite, re-situate, and re-sight the past in provocative ways. [ABSTRACT FROM AUTHOR]

Experiments suggest that some hosts that reject parasitic brown-headed cowbird (Molothrus ater) eggs develop egg recognition by imprinting on their own eggs, probably at the first nest naïve birds attend. This raises the possibility that parasitism of naïve individuals might cause them to mistakenly misimprint on, and accept, cowbird eggs. In an egg-learning experiment designed to cause misimprinting, hosts accepted cowbird eggs when they had laid only 1 egg even though most rejected cowbird eggs when nests had ≥2 host eggs. These findings show that cowbirds can cause misimprinting by parasitizing naïve hosts. If done opportunistically, misimprinting should become more likely as cowbird abundance increases. In accord with this expectation, simulated brood parasitism showed that 3 host species that usually reject cowbird eggs were more tolerant of cowbird eggs in the Great Plains, where cowbirds reach maximal historic abundance, than in eastern North America where cowbirds are less common. This relation between parasite abundance and host responses is opposite to that found in cuckoo hosts. In addition, these 3 rejecter species had high rates (10.8–30.4%) of natural cowbird parasitism at an Illinois site where cowbirds are extremely, and historically, abundant. These rejecters accepted most cases of researcher-detected parasitism, even though they rarely accept where cowbirds are less common. Despite the potentially high cost resulting from egg rejection, we demonstrate that parasitism of “rejecters” can be adaptive for cowbirds particularly when host egg recognition involves learning. [ABSTRACT FROM AUTHOR]