Landscape heterogeneity drives intra‐population niche variation and reproduction in an arctic top predator

Abstract

While intra-population variability in resource use is ubiquitous, little is known of how this measure of niche diversity varies in space and its role in population dynamics. Here we examined how heterogeneous breeding environments can structure intra-population niche variation in both resource use and reproductive output. We investigated intra-population niche variation in the Arctic tundra ecosystem, studying peregrine falcon (Falco peregrinus tundrius, White) breeding within a terrestrial-marine gradient near Rankin Inlet, Nunavut, Canada. Using stable isotope analysis, we found that intra-population niches varied at the individual level; we examined within-nest and among-nest variation, though only the latter varied along the terrestrial-marine gradient (i.e., increased among-nest variability among birds nesting within the marine environment, indicating higher degree of specialization). Terrestrial prey species (small herbivores and insectivores) were consumed by virtually all falcons. Falcons nesting within the marine environment made use of marine prey (sea birds), but depended heavily on terrestrial prey (up to 90% of the diet). Using 28-years of peregrine falcon nesting data, we found a positive relationship between the proportion of terrestrial habitat surrounding nest sites and annual nestling production, but no relationship with the likelihood of successfully rearing at least one nestling reaching 25 days old. Annually, successful inland breeders raised 0.47 more young on average compared to offshore breeders, which yields potential fitness consequences for this long-living species. The analyses of niche and reproductive success suggest a potential breeding cost for accessing distant terrestrial prey, perhaps due to additional traveling costs, for those individuals with marine nest site locations. Our study indicates how landscape heterogeneity can generate proximate (niche variation) and ultimate (reproduction) consequences on a population of generalist predator. We also show that within-individual and among-individual variation are not mutually exclusive, but can simultaneously arise and structure intra-population niche variation.

Rapid Nestling Mortality in Arctic Peregrine Falcons due to the Biting Effects of Black Flies

“…A dense population of Peregrine Falcons breeding near the hamlet of Rankin Inlet, Nunavut, Canada (62˚49′ N, 92˚05′ W), has been intensively monitored since 1982 (Court et al, 1988a(Court et al, , b, 1990Johnstone et al, 1996;Bradley et al, 1997;Franke et al, 2010Franke et al, , 2011Franke et al, , 2013Anctil and Franke, 2013;L'Hérault et al, 2013;Anctil et al, 2014). Terminology used in describing nesting activities of Peregrine Falcons and a general description of the vegetation, climate, and geology of the study area are reported elsewhere (Court et al, 1988a, b).…”

Multi-scale selection models predict breeding habitat for two Arctic-breeding raptor species

“…The selection of productive areas in close proximity to water by peregrine falcons and rough-legged hawks was likely linked to the availability of accessible prey (Wightman and Fuller 2005;Booms et al 2010;Coulton et al 2013). Arctic-breeding passerines and shorebirds are more abundant in well-vegetated lowlands and wetlands than in sparsely vegetated areas (Robinson et al 2014), and are a key food source for breeding peregrine falcons (Court et al 1988;L'Hérault et al 2013;Robinson et al 2017). Furthermore, the abundance and distribution of Arctic grazers such as lemmings, which are important prey for peregrine falcons (Bradley and Oliphant 1991;L'Hérault et al 2013;Robinson et al 2017) and rough-legged hawks (Potapov 1997;Bechard and Swem 2002) are also correlated with tundra productivity during summer (Rodgers and Lewis 1986;Olofsson et al 2012).…”

“…Arctic-breeding passerines and shorebirds are more abundant in well-vegetated lowlands and wetlands than in sparsely vegetated areas (Robinson et al 2014), and are a key food source for breeding peregrine falcons (Court et al 1988;L'Hérault et al 2013;Robinson et al 2017). Furthermore, the abundance and distribution of Arctic grazers such as lemmings, which are important prey for peregrine falcons (Bradley and Oliphant 1991;L'Hérault et al 2013;Robinson et al 2017) and rough-legged hawks (Potapov 1997;Bechard and Swem 2002) are also correlated with tundra productivity during summer (Rodgers and Lewis 1986;Olofsson et al 2012). Nesting site selection was associated with low NDVI, which likely indicates that habitat within 50 m of nesting sites was bare rock typical of cliff faces, slot canyons, and rock outcrops on which breeding pairs were detected.…”

“…White, 1968) is listed as "Special Concern" under the Canadian Species at Risk Act (SARA 2002, as amended), and is regarded as a valued component of Arctic ecosystems in environmental assessments. Arctic peregrine falcons are considered generalist predators, but the bulk of their diet consists of insectivorous birds (Passeriformes, Scolopacidae, and Charadriidae; Hunter et al 1988;Rosenfield et al 1995;Dawson et al 2011;L'Hérault et al 2013). Peregrine falcons typically nest on cliffs and rocky outcrops of varying height, but also use hill tops, river canyons, and rock screes.…”

Assessment of Peregrine Falcon (Falco peregrinus anatum) Nesting Habitat in the San Francisco Bay Area

“…used GIS to predict the breeding sites of the powerful owl (Ninox strenua) in urban Melbourne, Australia. In two other studies of Eleonora's falcon (Falco eleonorae) and the peregrine falcon (Falco peregrinus tundrius) respectively, GIS was used in model predictions to determine proportions of topological features such as vegetation coverage and urban features as a function of nesting territory within the study area(Kassara et al, 2012;L'Hérault, Franke, Lecomte, Alogut, & Bêty, 2013) Dykstra, Simon, Daniel, and Hays (2012). conducted a habitat assessment study using GIS to map suburban Barred owl (Strix varia) and Red-shouldered hawk (Buteo lineatus) nest locations with GPS-derived coordinates that were then overlaid on digital land cover dataset obtained from the National Land Cover Database (NLCD) and…”