Nesting and roosting habitat and breeding biology of the barn owl (Tyto alba) in the Lower Mainland of British Columbia
Notice bibliographique
Résumé
Nesting and roosting habitat use and breeding biology of the barn owl (Tyto alba pratincola) in the Lower Mainland of British Columbia were studied over 3 years from 1990-92. A total of 236 sites used by barn owls were located, all but 9 of which were man-made. The majority of the sites (72%) were barns, then silos (11 %) and industrial buildings (4%). Natural nest sites were located in both live trees and snags. It is suggested that barn owls choose man-made sites over natural sites because of the increased thermal cover and increased security from predators. Yearly variations in brood size and the mean number of young fledged per nest were observed, with the lowest values for both recorded in 1991. Poor environmental conditions are thought to be responsible for lowered breeding success in this case. The 3 year mean clutch size, brood size and number of young fledged per nest and their standard deviations were 6.5 (+ 3.5), 3.3 (± 2.0) and 2.6 (±2.1), respectively. Taxidermy data provided information on mortality of adult barn owls. Road kills were found to account for the largest proportion (62.9%) of the carcasses, with starvation (16.7%) and unknown causes (14.6%) making up most of the remainder. Mortality in general was lowest in the summer and highest in the winter. Examination of banding records revealed an average age of 28.1 months at death, with most birds being recovered less than 20 km from their place of banding. Contrary to published hypotheses, no evidence of southward migration could be found. Six adult barn owls were radio-tracked and each was found to have a favoured roost site at which it could be located most of the time. The barn owls roosted at both manmade and natural sites, the choice of which seemed to depend on the preferences of the individual. Several barn owl nestbox programs have been initiated in the Lower Mainland and preliminary results from 2 of the programs show occupancy of the boxes at 31-57% about 2 years after the installation of the boxes. Examination of the history of agriculture in the Lower Mainland reveals that acreage of prime barn owl hunting habitat such as pasture and unimproved pasture are declining. The future of the barn owl in the Lower Mainland depends upon the efficacy of farmland conservation programs such as the Agricultural Land Reserve in preserving farmland from urban development.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».