Spelling suggestions: "subject:"kestrels."" "subject:"estrela.""
1 |
Population ecology, food and conservation of the Seychelles kestrel (Falco araea) on MahéWatson, Arthur Jeffrey January 1981 (has links)
A study of the endemic kestrel on the island of Mahe in Seychelles was carried out over three years, 1975-77. Emphasis was placed on population dispersion, breeding biology, food and conservation. Kestrels occupied exclusive home ranges which were actively defended and nest sites were significantly over-dispersed. Removal experiments demonstrated the existence of a non-breeding surplus. Egg-laying occurred each year between August and October and one brood was reared per annum. Laying occurred consistently at a time of increasing food availability and young were in the nest when food availability was at a maximum. Clutch size was two or three, incubation lasted 30 days, the nestling period 38 days and the post-fledging period 9-24 weeks. In upland areas (> 200 m) 68% of pairs nested In cliffs and the remainder in trees. On the coast 44% used coconut palms, 27% cliffs, 17% trees and 12% buildings. Only 18% of pairs nesting in palms fledged young compared with 35% in buildings, 67% in trees and 75% in cliffs. This difference was attributed to differences in predation levels reflecting relative 'insecurity' of nest sites in palms and buildings. Overall breeding success in 1977 was significantly depressed compared with 1975 and 1976. This was attributed to food shortage in 1977. Kestrels occupied a range of habitats from open-country to mixed forest and took prey from the ground and throughout the full vertical range of vegetation. In terms of 'number of items' vertebrates comprised 56% and invertebrates (exclusively insects) 44% of the diet. Lizards constituted 92% of the vertebrate component, with the green gecko (Phelsumo) 67%, and the ground skink (Mabuya) 31%. In terms of 'biomass' lizards comprised 70%, 'other vertebrates' 20% and Insects 10%. In the last 100 years the kestrel has become extinct on the islands in the Praslin-La Digue group and yet has survived on Mahe, Silhouette and adjacent islands which together have a contemporary population of about 420 pairs. The low breeding success caused by high levels of predation at coastal sites on Mahe was considered insufficient to sustain populations of kestrels without a continual influx of young from upland areas. Such upland areas (and therefore reservoirs of high breeding success) are much fewer on the Praslin-La Digue group and this is considered to be, at least part of the explanation for the extinction of kestrels on Praslin-La Digue.
|
2 |
Reproductive success of southeastern American kestrels (Falco sparverius paulus) nesting in 230kV transmission towers and alternative nest structures in south-central GeorgiaBeasley, Hope Alyce. January 2007 (has links) (PDF)
Thesis (M.S.)--Georgia Southern University, 2007. / "A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." In Biology, under the direction of John W. Parrish. ETD. Electronic version approved: December 2007. Includes bibliographical references (p. 26-29)
|
3 |
Variations in plasma corticosterone, estrone, estradiol - 17l and progesterone concentrations with reproduction, molt, hematocrit and body weight of captive female American kestrelsPon, Nancy Barbara Rehder. January 1983 (has links)
No description available.
|
4 |
Variations in plasma corticosterone, estrone, estradiol - 17l and progesterone concentrations with reproduction, molt, hematocrit and body weight of captive female American kestrelsPon, Nancy Barbara Rehder. January 1983 (has links)
No description available.
|
5 |
The effect of fluoride on reproductive performance and growth of captive American kestrels /Carrière, Daniel. January 1985 (has links)
No description available.
|
6 |
The effect of fluoride on reproductive performance and growth of captive American kestrels /Carrière, Daniel. January 1985 (has links)
No description available.
|
7 |
Aspects of the foraging and breeding ecology of the Southern African Kestrel, Falco tinnunculus rupicolusVan Zyl, Anthony John January 1993 (has links)
Includes bibliography. / A study of the ecology of the Southern African Kestrel was made in two areas of differing topography in the Eastern Cape Province (32 °S) of South Africa. The main objectives of the study were to describe foraging parameters (behaviour-time budgets, hunting success and diet) and breeding parameters (clutch size, hatching and fledging success, nestling, fledging and post-fledging periods) of the Southern African Kestrel. These parameters were compared to those from studies made on the European Kestrel (Falco tinnunculus tinnunculus) in western Europe (53 °N) in an environment which fluctuates relatively more than the South African study sites. Predictions concerning foraging and breeding ecology made by life-history theory in stable and fluctuating environments prompted the erection of the following hypotheses which were examined in this study. 1. Common Kestrels (Falco tinnunculus) in relatively stable environments have a more consistent but lower foraging yield than those breeding in fluctuating environments. 2. Common Kestrels in relatively stable environments have lower reproductive rates (longer incubation, nestling and post-fledgling dependence periods, later age at first breeding and longer life-span) than those in fluctuating environments. Southern African Kestrels spent different proportions of time of the two main hunting methods used, perch- and hover-hunting, than the European Kestrel. Perch-hunting was the predominant hunting method used by the Southern African Kestrel compared to hover-hunting in the European Kestrel. Southern African Kestrels had a higher prey-capture success for both hunting techniques. However, daily food intake was lower in Southern African Kestrels because a high proportion of the diet consisted of small invertebrates. Average clutch size was smaller in the Southern African Kestrel than that of the European Kestrel and Southern African Kestrels fledged on average fewer young. However, incubation, nestling and post-fledging periods were within the range recorded for the European Kestrel. The hypothesis that Common Kestrels in relatively stable environments have lower foraging yields is supported by this study. Although results from this study suggest that food yields are more consistent in stable environments, it was unable to evaluate this adequately. The hypothesis that reproductive rates are lower in relatively stable environments is partly supported in this study, but more data are required for parameters such as incubation and nestling periods to confirm such trends.
|
8 |
The influence of relatedness, weight, and age on the mate choice of captive female American kestrels /Duncan, James R. January 1985 (has links)
No description available.
|
9 |
Mate replacement in wild American kestrelsBowman, Reed. January 1985 (has links)
No description available.
|
10 |
The influence of relatedness, weight, and age on the mate choice of captive female American kestrels /Duncan, James R. January 1985 (has links)
No description available.
|
Page generated in 0.0457 seconds