Prey Selection by Peregrine Falcons during the Nestling Stage

Hunter, R. E.; Crawford, John A.; Ambrose, Robert E.

doi:10.2307/3800938

Cited by 25 publications

(14 citation statements)

References 11 publications

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“…Our results are unusual, especially for Peregrine Falcons. We estimated diet from pellets, but White and Cade (1971) and Hunter et al (1988) estimated diet from prey remains at nests. The latter method tends to underestimate the contribution of small mammals to raptor diets, because the entire carcass is often ingested or small bones are lost in the nest structure (Marti 1987, Simmons et al 1991.…”

Section: Generalist Predator Hypothesismentioning

confidence: 99%

Patterns of Predation on Noncyclic Lemmings

Reid¹,

Kenney²

1997

Ecological Monographs

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Noncyclic populations of microtine rodents may be limited within a relatively constant range of densities by generalist predators with a prey base sufficiently diverse to sustain them when rodents are scarce (generalist predator hypothesis). Collared lemmings (Dicrostonyx kilangmiutak) at Pearce Point, Northwest Territories, Canada, are noncyclic and limited to fairly constant low densities in summer by predation, principally by red fox and Rough-legged Hawks. We tested four predictions of the generalist predator hypothesis as a possible explanation for relatively constant lemming densities: (1) predators do not show strong numerical responses to lemming density; (2) the proportion of lemming biomass in predator diets declines with declining lemming abundance, compensated for by increased consumption of alternative prey; (3) predators show a type-III functional response to lemming density; and (4) at low densities, predation on lemmings ceases.The first prediction was not satisfied by the principal predators: at very low lemming densities, Rough-legged Hawks did not settle, and breeding success of red foxes and hawks was limited by lemming abundance. However, a number of generalist predators (Golden Eagle, grizzly bear, arctic ground squirrel, Peregrine Falcon, and Gyrfalcon) did not respond numerically to the lowest lemming densities. The second prediction was partly supported: all predators consumed lemmings at a lower rate as lemming densities declined. However, Rough-legged Hawks were not able to compensate fully for the declining consumption by increasing their use of alternative prey, and red foxes were able to do so in one of three years. Regarding the third prediction, foxes showed some evidence of a type-III functional response but hawks did not. As for the fourth prediction, most predators still consumed lemmings at very low densities; lemmings lacked a secure refuge. The Pearce Point system differs from those where microtine dynamics are relatively constant and nonirruptive because of persistent predation by generalists. In terms of biomass, lemmings are the principal prey for their dominant predators. These predators (the semigeneralist red fox and the specialist Rough-legged Hawk) rely on lemmings to breed, but drive them to densities too low to sustain breeding by these same predators in the subsequent spring. In this regard, the system is similar to one driven by specialists. In some winters, however, populations recover because lemmings breed under the snow and most summer predators are absent. As a result, lemming densities in spring are often high enough for specialists and semigeneralists to initiate breeding. When winter breeding and survival fail to allow population growth, hawks and foxes may fail to breed and then leave the system. Even so, summer generalists still persist and continue to consume lemmings, curtailing potential irruptive growth. In this regard, the system is similar to one where prey are relatively constant because of generalists.Community dynamics at Pearce Point can best b...

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Section: Generalist Predator Hypothesismentioning

confidence: 99%

Patterns of Predation on Noncyclic Lemmings

Reid¹,

Kenney²

1997

Ecological Monographs

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Section: Methodsmentioning

confidence: 99%

“…To assess whether the heterogeneity of the breeding environment influenced the diet of nestling falcons and adult reproductive success for nestling rearing falcons (mid July to late August), we first calculated a pseudo home range for each pair of breeding falcon by buffering each nest with a 5 km radius circle (Hunter et al 1988;Byholm et al 2007). Five kilometers was selected because it is within the typical range of foraging distance for breeding peregrine falcon observed in other studies (A. Franke, M. Prostor, V. L'H erault and J. Bety, unpubl.…”

Section: Study Design: Quantifying the Heterogeneity Of The Breeding mentioning

confidence: 99%

“…The multi‐species diet of the arctic‐breeding peregrine falcon (Cade ; Hunter et al. ; Rosenfield et al. ) makes it an ideal study species for examining niche variation.…”

Section: Introductionmentioning

confidence: 99%

“…Initially launched to study contamination levels of dichloro-diphenyl-trichloroethane (DTT) after the peregrine falcon was listed as a threatened species under the Canadian Species at Risk Act (Cooper and Beauchesne 2007), this program provides long-term monitoring of breeding success and short-term sampling of resource use, an avian parallel to what was done on arctic foxes by Giroux et al (2012). The multi-species diet of the arctic-breeding pere-grine falcon (Cade 1960;Hunter et al 1988;Rosenfield et al 1995) makes it an ideal study species for examining niche variation. Compared with their southern counterparts which rely on a bird prey base (Ratcliffe 1980;White et al 2008), peregrine falcons nesting in the Arctic are regularly observed using mammalian prey species (lemmings -Lemmus trimucronatus and Dicrostonyx groenlandicus Traill-and ground squirrel Spermophilus paryii Richardson) and this behaviour may bear consequences on demographic processes (e.g., lemmings spp.…”

Section: Introductionmentioning

confidence: 99%

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

L'Hérault

Franke²,

Lecomte

et al. 2013

Ecology and Evolution

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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.

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Recovery of American peregrine falcons along the upper Yukon River, Alaska

et al. 2016

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American peregrine falcons (Falco peregrinus anatum) throughout North America declined following the introduction of dichlorodiphenyltrichloroethane (DDT) in 1947. In the 1960s, intensive studies were initiated in many areas of North America, including interior Alaska, to determine the cause of the decline and assess population status. From 1977 to 2015, we studied peregrine falcons along a 265‐km section of the upper Yukon River in east‐central Alaska. We counted occupied territories, documented breeding success and productivity, and collected unhatched eggs for contaminant analysis. We observed 1,602 occupied territories and 2,349 nestlings. Annual breeding success averaged 64%, and annual productivity averaged 1.54 nestlings/territory and 2.38 nestlings/successful territory. Annual rates of increase in the number of occupied territories were greatest in the late 1970s and 1980s (8.6%), moderate in the 1990s (2.8%), and least in the 2000s (1.5%). Reproductive metrics were highest in the late 1970s and 1980s, declining in recent years. As the number of occupied territories increased (14–60) and average nearest neighbor distance decreased (from 9.8 km to 2.6 km), breeding success declined (from 71% in the 1980s to 57% in the 2000s). Productivity, as measured by nestlings per occupied territory, declined (from 1.84 in the 1980s to 1.29 in the 2000s). Nestlings per successful territory also declined from 2.56 in the 1980s to 2.25 in the 2000s. Survey data for 1966–2015 reveal a declining population in the 1960s and early 1970s, increasing in the late 1970s through the early 2000s, and apparently stabilizing in recent years. The recovery of this local population took roughly 40 years, from a low of 12 occupied territories in early 1970s to 60 in 2012–2014. Importantly, the recovery of American peregrine falcons in Alaska occurred without captive breeding, releases, or nest site manipulations. Long‐term studies are essential in fully understanding the biology of any species, and this study provides insight into the unaided, natural recovery of American peregrine falcons in Alaska. © 2016 The Wildlife Society.

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Prey Selection by Peregrine Falcons during the Nestling Stage

Cited by 25 publications

References 11 publications

Patterns of Predation on Noncyclic Lemmings

Patterns of Predation on Noncyclic Lemmings

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

Recovery of American peregrine falcons along the upper Yukon River, Alaska

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