Habitat selection of Leach's storm petrel (Oceanodroma leucorhoa) in three Newfoundland colonies

Grimmer, Barbara Lee (1980) Habitat selection of Leach's storm petrel (Oceanodroma leucorhoa) in three Newfoundland colonies. Masters thesis, Memorial University of Newfoundland.

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Abstract

Habitat selection of Leach's Storm Petrel (Oceanodroma leucorhoa) was studied in three Newfoundland colonies of this species. Habitat preferences as inferred by petrel burrow densities were examined and quantified (Study 1 and 2). Of habitat parameters studied, peat depth, tall vegetation and fern type vegetation were positively related to increasing petrel burrow density. Habitat preferences as a function of burrow density varied between colonies. -- Burrow architecture was examined in one colony of petrels. Physical characteristics of the burrow may affect the internal microclimate of the burrow. Several burrow configurations were described which may serve to moderate internal burrow microclimates, maintaining a cool, stable environment in the burrow. The necessity for a cool, stable internal burrow environment is related to aspects of Leach's Storm Petrel life history which include early onset of nestling thermoregulation. -- Eggs, hatching data and chick weights in a high burrow density (HD) area of one colony were compared with these measures taken in a low burrow density (LD) area of the same colony (Study 4). Non-significant differences in egg size were found between the two areas. No differences were found between the two areas in probability of hatching. HD area chicks were heavier and were more likely to be alone in the burrow on a given date than were LD area chicks. -- A comparison of egg measurements from previous breeding seasons with the 1978 data suggests that egg dimensions (breadth and egg size) increase slightly with increased breeding experience of the female. -- The ontogeny of habitat preferences was studied. The assumption that habitat preferences are mediated by habitat imprinting was tested (Study 5). Chicks from homogeneous biomes were allowed to choose between samples of their natal biome and a novel biome in a maze. Four age groups were tested. The test results were inconclusive, as chicks chose biome types randomly. Possible reasons for the experimental failure are discussed.

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