Habitat use by Loggerhead Shrikes in Ontario and Quebec
Notice bibliographique
Résumé
Once common throughout northeastern North America, the migrant race of Loggerhead Shrike (Lanius ludovicianus migrans) has undergone a drastic decline since the middle of the last century. The subspecies was designated as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 1991. To gain a better understanding of the factors affecting the decline of this species in eastern Canada, habitat selection by Loggerhead Shrikes breeding in Ontario (Smith's Falls, Napanee, and Carden limestone plains) and southern Quebec was studied in 1991 and 1992. Nest trees used by breeding shrikes were compared with similar arbitrarily identified trees in suitable unoccupied habitat to determine if there was a nest-tree preference. Territories where successful nesting attempts were made (i.e., young fledged from at least one of the eggs laid) were located over a 2-year period; data were not collected for unsuccessful nests or nests used for double-brooding. Thirty-seven nests (50%) were located in hawthorn shrubs (Crataegus spp.) and 29 nests (40%) in red-cedar trees (Juniperus virginianus). White cedar (Thuja occidentalis), buckthorn (Rhamnus catharticus), and ash (Fraxinus spp.) were used infrequently (10%). Sixty-two nests (86%) were located in isolated trees or in a copse. Ten nests (14%) were located in hedgerows. Fifty-one (64%) nest sites were located in an actively grazed pasture. The other nest sites were located in idle pasture, hayfields, or old fields. Nest trees and arbitrarily chosen trees in suitable unoccupied habitat did not differ significantly in average height, width, or canopy concealment. Few differences were detected in the average height of the vegetation or the composition of ground cover within a 10-m radius of nest trees and arbitrarily chosen trees. The average numbers of shrubs per hectare did not differ between breeding sites and suitable unoccupied habitat. Nest trees in the Smith's Falls core breeding area were located significantly closer to roads than arbitrarily chosen trees in suitable unoccupied habitat. Habitat suitability was also assessed according to the density of perches (trees and shrubs), which directly affects the amount of actual utilizable habitat in a territory. Significant differences were found in the amounts of actual habitat and potential habitat. The amount of habitat around active nest sites, historic nest sites, and suitable unoccupied sites was significantly greater around active nest sites. Since few statistically significant differences were found between habitat occupied by shrikes and that which was not used, it is not possible to build a predictive model of suitable breeding habitat for shrikes in this study area.
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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 | 0,001 |
| 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 | 0,001 |
| Communication savante | 0,001 | 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) | 0,002 | 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 ».