No description available.

No description available.

Sex-specific growth analyses were conducted for 32 nestling ospreys (Pandion haliaetus) in a migratory population in Nova Scotia, Canada and for 31 nestling ospreys in a sedentary population in Sonora, Mexico. Eight variables including weight, body components and plumage characteristics were measured to document the influence of sex on growth performance. Within populations, males differed significantly from females in having lower weight and body component asymptotes but did not differ in plumage characteristics or growth rates. There was no difference in growth performance between individuals in broods of various sizes or within broods as a result of hatching order asynchrony. Comparisons of geographic variation showed that sedentary ospreys in Mexico had significantly higher weight and tarsus asymptotes, reduced growth rates, longer nestling periods and later emergence of flight feathers than migratory ospreys. Individual nestlings were initially identified by sex from karyotypic analysis of fibroblast tissue collected from a sample of 31 nestlings in the field. The karyotype is presented and growth performance is discussed within the framework of evolutionary theory.

No description available.

No description available.

Various aspects of Osprey biology, Pandion h. haliaetus, were studied from museum specimens and in the field. Size, breast markings and crown markings were found insufficient to discriminate populations, but underwing coverts were sufficient. Four subspecies were recognized, corresponding to the Palearctic, North America, the Bahamas and Australasia. However Ospreys can be divided into two groups, a Holarctic group, consisting of Palearctic, North American and Bahaman Ospreys, and the Australasian Ospreys. Ecology was studied in Senegambia during two visits in 1977-80. Over 800 Ospreys were estimated to winter there, mostly at river mouths and in mangrove. Marked Ospreys returned to the same area in consecutive years, and stayed within that area during winter. Dispersion along the coast was random except at a few localities where the birds concentrated. In mangrove, birds were regularly spaced at high tide but went to the coast or more open mangrove at low tide. Along the coast, Fish Eagles, Haliaeetus yocifer, and Ospreys seemed independently distributed, but in mangrove Ospreys avoided hunting in sight of a Fish Eagle, while along rivers and lakes eagles might have excluded Ospreys. The diet consisted mostly of Mugilidae, various Clupeidae, and, during part of winter, of Exocoetidae. Average fish size was generally 200-300 g, but fish were smaller in areas well protected from the open sea. Dive success and search time per capture varied between sites, partly because they were significantly correlated with fish size. Immatures 6 months old were less successful at catching fish than older birds. Foraging efficiency varied from 2.9 to 10 kcal/minute of foraging. Most Ospreys were found in mangrove even though foraging efficiency was lower there. This was most likely because hunting from a perch in mangrove was less demanding than hunting from flight elsewhere. Moult was studied from captured Ospreys and museum skins. A few Ospreys were caught more than once so that the development of the moult pattern of the primaries could be traced. Limits to the growth rate of feathers are emphasized as a major reason for the evolution of the Staffelmauser pattern of moult in large birds. Ospreys do not breed in the tropics, except in Australasia, even though the habitat seemed ecologically suited. In particular, foraging efficiency was as high in Senegambia as on the north-temperate breeding grounds. It is suggested that migrants Ospreys are physiologically inhibited from breeding in the tropics because daylength is too short, while south of the tropic of Capricorn, where migrants might be stimulated to breed, but six months out of phase, they are too scarce to start a permanent breeding population. It is suggested that non-migratory Ospreys have not spread their range south because of the presence of large numbers of migrants in the tropics.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2004. / Includes bibliographical references (leaves 33-41).

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 87 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 72-73).

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains viii, 93 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 80-81).

This thesis argues that humans and ospreys in Scotland are materially, bodily and ethically involved with one another. It follows that a separate human or osprey history of species conservation is inadequate. Focused primarily through the entwined experiences of birds and people on Speyside, I examine the unfolding of osprey-human relationships with particular attention to the agency and capacities of nonhuman animals as animals: with geographies and lives of their own. Drawing on the scholarship of Tim Ingold, Giles Deleuze and Donna Haraway, I consider the dwelling, the co-becoming, and the zones of attachment between human and osprey subjects. At the heart of this project has been an investigation of the relationship between the historical and geographical conditions within which osprey life has flourished on its return from extinction in Scotland, and the possibilities for osprey nature that emerge from such conditions. I offer a ‘site ontology’ of osprey involvements, each ‘site’ comprising a material, bodily and ethical event of agency, subjectivity and composition. Often running in parallel to each other, such sites emphasise differentiations of osprey life: their situation within the militarised biopolitics of bird protection and ‘Operation Osprey’; negotiations of avian-human proximity and distances; their nesting geographies amidst the experimental attempts to restore a diminished community to its former range; and the nature of avian existence emerging in the wake of a return from extinction. Drawing on an array of archival material – occasionally supplemented with oral history, avian science and encounters in the field – the thesis proposes a lively historical geography of animal involvement.