Vegetation influences patch occupancy but not settlement and dispersal decisions in a declining migratory songbird

Abstract

Territorial clustering within larger, continuous patches of seemingly appropriate habitat could indicate that a species has additional, finer scale habitat requirements. Studying fine-scale (e.g., territory-level) habitat selection using methods that elucidate individual preferences may allow us to identify resources that influence species distributions. We examined breeding territory selection in the sagebrush Brewer's Sparrow (Spizella breweri Cassin, 1856) at the northern extent of its range to test for influences on fine-scale habitat selection. We used an information-theoretic approach to evaluate models relating a suite of vegetation characteristics to breeding habitat selection. We employed two methods: (1) assessment of patch occupancy at a territory scale and (2) examination of individual decisions relating to settlement and dispersal. We found that patch occupancy was most consistently predicted by models that included the cover of big sagebrush (Artemisia tridentata Nutt.) with the greatest likelihood of occupancy at 20%-25% cover. However, assessment of settlement and dispersal decisions did not identify additional fine-scale preferences for other vegetation characteristics. Vegetation cover also did not influence breeding success, indicating that within the vegetation range found in Brewer's Sparrow territory clusters, there is little benefit in basing individual settlement or dispersal decisions on vegetation cover. Résumé : Le regroupement d'un territoire avec des taches d'habitat en apparence appropriées, mais plus grandes et continues, pourrait indiquer qu'une espèce possède des besoins additionnels d'habitat à une échelle plus fine. L'étude de la sélection d'habitat à échelle fine (par ex., au niveau du territoire) en utilisant des méthodes qui mettent en lumière les préférences individuelles permet peut-être d'identifier les ressources qui influencent la répartition des espèces. Nous examinons la sélection du territoire de reproduction chez le bruant de Brewer des armoises (Spizella breweri Cassin, 1856) à la limite boréale de son aire de répartition afin de vérifier les influences sur la sélection d'habitat à échelle fine. Nous utilisons une approche basée sur la théorie de l'information afin d'évaluer des modèles qui relient une série de caractéristiques de la végétation à la sélection de l'habitat de reproduction. Nous employons deux méthodes, (1) une évaluation de l'occupation des taches à l'échelle du territoire et (2) un examen des décisions individuelles concernant l'établissement et la dispersion. Ce sont les modèles qui incluent la couverture de la grande armoise (Artemisia tridentata Nutt.) qui prédisent l'occupation des taches de la façon la plus constante; la plus grande probabilité d'occupation se situe à une couverture de 20 % -25 %. L'évaluation des décisions d'établissement et de dispersion n'a pas, cependant, identifié de préférences additionnelles à échelle fine pour d'autres caractéristiques de la végétation. De plus, la couverture végétale n'influence pas le succès de la rep...

Riparian habitat disturbed by reservoir management does not function as an ecological trap for the Yellow Warbler (Setophaga petechia)

“…Tracking individual decision-making is a more direct and potentially more reliable method of gathering information about habitat preference. For example, several studies on migratory birds have used the order in which territories are occupied in the spring to examine habitat preferences (e.g., Arlt and Part 2007;Harrison and Green 2010). Nest success and the number of fledglings produced during a nesting attempt provides information on predation rates and food availability within a habitat (Martin 1993) and is directly linked to individual fitness.…”

The effects of management practices on grassland birds—Brewer’s Sparrow (<i>Spizella breweri breweri</i>)

“…vaseyana), and Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) (Huey and Travis, 1961;Fautin, 1975;McGee, 1976;Wiens and Rotenberry, 1981;Rotenberry, 1986;Wiens and others, 1986;Cannings and others, 1987;Sedgwick, 1987;Knopf and others, 1990;Kerley and Anderson, 1995;Welch, 2002Welch, , 2005Noson and others, 2006;Chalfoun and Martin, 2007;Harrison and Green, 2010;Vander Haegen and others, 2015;Rotenberry and others, 2020). Other dominant or codominant shrubs in Brewer's Sparrow habitat may include threetip sagebrush (Artemisia tripartita), dwarf sagebrush (Artemisia scopulorum), black sagebrush (Artemisia nova), little sagebrush (also commonly referred to as low sagebrush; Artemisia arbuscula), white sage (Salvia apiana), Bigelow sage (Artemisia bigelovii), tarragon (Artemisia dracunculus), green (also commonly referred to as yellow) rabbitbrush (Chrysothamnus viscidiflorus), rubber rabbitbrush (Ericameria nauseosa), greasewood (Sarcobatus spp.…”

“…Within occupied sites, Brewer's Sparrow abundance was positively associated with percent cover of threetip sagebrush, parsnipflower buckwheat, silky lupine (Lupinus sericeus), sagebrush, and litter (Paczek, 2002;Paczek and Krannitz, 2005). In another study in the South Okanagan Region of British Columbia, however, Brewer's Sparrow occupancy was best predicted by the cover of big sagebrush, with the greatest likelihood of occupancy occurring at 20-25 percent cover of big sagebrush; forb cover and grass cover were not good predictors of occupancy (Harrison, 2008;Harrison and Green, 2010).…”

Crop type influences edge effects on the reproduction of songbirds in sagebrush habitat near agriculture

“…We averaged each vegetative characteristic to obtain a value at each study plot. These vegetation survey methods follow methods previously used in the study area to allow for direct comparison in future studies (Paczek andKrannitz 2004, Harrison andGreen 2010). Vegetation at each plot was measured at the end of the breeding season to avoid disturbing any songbird nests.…”