Ferruginous and Swainson's hawk abundance and distribution in relation to land use in southeastern Alberta [Buteo regalis, Buteo swainsoni]

• Published in: The Journal of wildlife management 1984-10, Vol.48 (4), p.1180-1187
• Main Author: Schmutz, J.K
• Format: Article
• Language: English
• Subjects: ALBERTA; Animal and plant ecology; Animal nesting; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Bird nesting; Birds of prey; Breeding; Buteo regalis; DENSIDAD DE LA POBLACION; DENSITE DE POPULATION; DISTRIBUCION NATURAL; DISTRIBUTION NATURELLE; EPERVIER; Fundamental and applied biological sciences. Psychology; GAVILAN; Grasses; HABITAT DESTRUCTION; HAWKS; LAND USE; NATURAL DISTRIBUTION; NESTING; Nesting sites; NIDIFICACION; NIDIFICATION; POPULATION DENSITY; Population estimates; Population size; Prairies; UTILISATION DU SOL; UTILIZACION DE LA TIERRA; Vertebrata
• ISSN: 0022-541X; 1937-2817
• DOI: 10.2307/3801779

Eighty$41-\text{km}^{2}$(4.4% of total area) sample plots were selected at random in a$74,686-\text{km}^{2}$area in southeastern Alberta and searched for nesting ferruginous (Buteo regalis) and Swainson's hawks (B. swainsoni). The estimated number of nesting ferruginous hawks was 1,082 pairs (±429) and the number of Swainson's hawks 3,879 pairs (±802). Ferruginous, but not Swainson's, hawks declined in abundance as the proportion of land under cultivation increased. Swainson's hawks nested in close proximity to human habitation whereas ferruginous hawks did not. The abundance of ferruginous hawks may be limited by the availability of grassland habitat, or by the survival of the hawks with only preferred habitat types occupied. The size and number of plots sampled was more than adequate to minimize sample variance but confidence intervals were wide because only 4.4% of the total area was sampled.