Food abundance determines distribution and density of a frugivorous bird across seasons

Abstract

Although food abundance is a principal determinant of distribution and abundance of many animals, most previous studies have not quantitatively assessed its importance relative to other factors that may also determine species distributions. We estimated frugivorous phainopepla Phainopepla nitens occupancy and density, food density, and vegetation structure on transects in fragmented mesquite and acacia woodlands over three years in non‐breeding and breeding seasons. Using an AIC framework and controlling for detection probability, we determined relative impacts of food abundance, vegetation structure, and habitat fragmentation on patch occupancy and density, and concomitant extinction and colonization probabilities of phainopeplas. Initial occupancy in winter 2002 was high (0.87 ± 0.047), and primarily positively correlated with food abundance and woodland area (Akaike weights wi= 0.998 and 0.750 respectively). Woodland area more strongly influenced occupancy where food was scarcer. Phainopepla density in both seasons was strongly positively correlated with food abundance, especially in the 2002 drought when density was higher (wi=1.0 for food and year). Density was higher in acacia than mesquite woodlands (wi= 1.0), and moderately negatively correlated with elevation (wi= 0.789). Extinction probability (patches vacated) was low (0.078 ± 0.040), and principally influenced by phainopepla density (wi= 0.968) and tree height (wi= 0.749). Colonization probability was low (0.15 ± 0.034) and determined by vegetation structure (wi= 1.0). Much recorded colonization was reoccupancy of woodlands previously occupied by single males in winter, then vacated in a breeding season. These results suggest that for an animal occupying a highly fragmented landscape, distributions and densities at the habitat patch scale are driven by food abundance, are moderately affected by habitat fragmentation, and are slightly influenced by vegetation structure.

Assessing the Habitat Suitability of Two Different Artificial Wetland Habitats Using Avian Community Structures

“…The occurring of water, rich food resources (i.e., amphibians, reptiles, small mammals, aquatic as well as terrestrial invertebrates and fishes) and diverse vegetation types had provided ideal habitat for a wide array of water and terrestrial bird individuals. It was observed that avian community structures in the marsh and lake areas were influenced by a number of variables such as water depth, vegetation structure and composition, food resources and foraging behaviour (Chimney and Gawlik, 2007;Michel et al, 2010;Crampton et al, 2011;Carrascal et al, 2012). It was also found that adjacent dry land area dominated by patches of shrubs and fruiting trees had also attracted a number of bird species particularly upland birds i.e., may be only facultative marsh inhabitants (Knight et al, 2001).…”

Does pollution influence small mammal diet in the field? A metabarcoding approach in a generalist consumer

“…Feeding behaviour is determined by life history traits and life stages of animals (Pyke, Pulliam, & Charnov, ; Schoener, ), abundance and distribution of food resources in nature (Crampton, Longland, Murphy, & Sedinger, ; White, ), and food quality (i.e., nutrient and toxin content; Butet, ; Kerley & Erasmus, ; Lewis, Clark, & Derting, ; Schmidt, ). All these factors are driven by ecological determinants such as season, climate, community interactions or landscape features (Polis, Anderson, & Holt, ; Visser & Both, ; White, ).…”

Human disturbance and stage‐specific habitat requirements influence snowy plover site occupancy during the breeding season

“…Birds should use breeding areas that maximize access to resources (Sergio and Newton ; Preston and Rotenberry ; Crampton et al. ) while minimizing predation risk to eggs, young, and adults (Ricklefs ; Martin and Roper ; Powell et al. ; Nguyen et al.…”

“…Habitat use has important consequences for avian reproductive success and survival (Matessi and Bogliani 1999;Doligez et al 2002;Sergio et al 2009). Birds should use breeding areas that maximize access to resources (Sergio and Newton 2003;Preston and Rotenberry 2006;Crampton et al 2011) while minimizing predation risk to eggs, young, and adults (Ricklefs 1969;Martin and Roper 1988;Powell et al 2002;Nguyen et al 2003). In seasonal and heterogeneous environments, habitat selection most likely occurs on several temporal and spatial scales (Hutto 1985) and, for species with precocial young, habitat requirements of different breeding stages may contribute to the complexity of habitat use.…”

“…In systems with seasonal changes in resources, or for species that utilize different habitats during different parts of the reproductive cycle, occupancy models that allow for movements within the breeding season may be useful (Betts et al 2008;Rota et al 2009;Crampton et al 2011). For example, Betts et al (2008) showed that young black-throated blue warblers, Setophaga caerulescens, initially occupied sites at random and then moved to more suitable territories once more information on habitat quality was available for the birds.…”