Numbers, breeding performance, and diet of the sparrowhawk Accipiter nisus and merlin Falco columbarius in relation to cone crops and seed-eating finches

Patterson, I. J.; Anderson, D. I. K.; Little, Brian R.; Davison, M.

doi:10.1016/0378-1127(95)03624-5

Cited by 35 publications

(17 citation statements)

References 20 publications

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“…1). This type of habitat is characterized by marked annual changes in the size of the cone crop, particularly in the spruce species (Andre Ân & Lemnell, 1992;Petty et al, 1995), seasonal variations in seed food availability with regard to cone maturation (pine vs spruces; Philipson, 1987;Gordon, 1992), and spatial variation in cone abundance and seed quality both within and between species (Gro È nwall, 1982). There are also signi®-cant differences in seed dispersal strategies between the 3 main conifer species.…”

Section: Study Areamentioning

confidence: 99%

Effects of temporal and spatial variations in food supply on the space and habitat use of red squirrels (Sciurus vulgaris L.)

Lurz¹,

2000

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In non-native conifer plantations characterized by strong spatial and temporal variations in the availability of tree seeds in Spadeadam Forest, northern England, the home range and habitat use of red squirrels Sciurus vulgaris was very¯exible. Males tended to have much larger home ranges than females and coreareas of most breeding females seemed mutually exclusive. Adult female red squirrels were found to increase their home range and core-area size in forest patches where food was less abundant. Home-range size was signi®cantly related to home-range quality and the extent of overlap by other females. In contrast with high-quality continuous conifer forests: (1) a considerable proportion of adult males and females at Spadeadam shifted home range, (2) both sexes had much larger home ranges than reported from other habitats in Britain or Belgium. Many ranges were multinuclear, particularly from January onwards, when supplies of seeds become depleted through consumption and seed shed. Squirrels tracked the availability of conifer seeds (lodgepole pine cones throughout the study, Norway spruce cones in spring 1992 and Sitka spruce cones in autumn 1993) and intensively used several non-adjacent activity centres in temporally food-rich patches. Consequently, habitat preference changed markedly with time. The squirrels seemed to maximize nitrogen intake and to avoid the smaller seeds when possible. This resulted in an overall preference for a mixed diet of lodgepole pine and spruce seeds and avoidance of Sitka spruce seeds when Norway spruce seeds were available. These results lend support to the hypothesis of Ostfeld (1985) that when food is sparse and patchily distributed, females should develop intrasexual territoriality, concentrating their activity in food-rich patches, while males should be non-territorial and adapt their space use to the distribution of females.

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Section: Study Areamentioning

confidence: 99%

Effects of temporal and spatial variations in food supply on the space and habitat use of red squirrels (Sciurus vulgaris L.)

Lurz¹,

2000

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“…6b), so the increase could not be explained simply by tawny owls switching to bank voles (and wood mice) when ®eld voles were scarce. Petty, Patterson et al, (1995) gave details of cone crops and how they were assessed in Kielder during 1974±1993. 7), but not in Sitka spruce.…”

Section: Temporal Variations In Nestling Dietmentioning

confidence: 99%

“…Further investigation implied that the proportion of bank voles in the tawny owl diet was linked to cone production in Norway spruce (Fig. These cones mature in the autumn, but seed dispersal occurs mainly in the following spring (Petty, Patterson et al, 1995). Petty, Patterson et al, (1995) gave details of cone crops and how they were assessed in Kielder during 1974±1993.…”

Section: Temporal Variations In Nestling Dietmentioning

confidence: 99%

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Diet of tawny owls (Strix aluco) in relation to field vole (Microtus agrestis) abundance in a conifer forest in northern England

Petty

1999

Journal of Zoology

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The diet of tawny owls Strix aluco was determined from pellets and prey items in owl nests in Kielder Forest, a planted spruce forest in northern England. Field voles Microtus agrestis were their most important food, and formed the highest proportion of tawny owl diet in winter and early spring. Common shrews Sorex araneus, common frogs Rana temporaria and birds were taken more frequently in late spring and summer. Clear cuts, areas from which timber had been felled at the end of the rotation, provided the main ®eld vole habitat in the forest and remained suitable for voles for 10±15 years after re-planting. Field vole abundance was measured three times a year on numerous clear cuts throughout the study area using a vole sign index based on fresh grass clippings in runways. Tawny owls responded functionally to the 3 to 4-year cycles of ®eld vole abundance. In years when voles were scarce, adult owls took more common shrews and common frogs, as determined from pellet analysis. In contrast, more bird prey was fed to nestlings when ®eld voles were scarce, as determined from prey items in nests. The proportions of the main prey in nests changed over a 19-year period. More bank voles Clethrionomys glareolus and wood mice Apodemus sylvaticus occurred in every year after 1992 than in any year before this. Numbers of wood mice in owl nests increased signi®cantly throughout the study period, whereas bank vole numbers exhibited noncyclic, multi-annual¯uctuations that were unrelated to ®eld vole cycles. It is argued that¯uctuations in rodent prey re¯ected changes in rodent guilds in the study area; reasons for this are discussed. This is the ®rst study of tawny owl diet in spruce forests in Britain and highlights the value of such large-scale dynamic habitats for rodent populations and their predators.

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“…Breeding tawny owls have been monitored continuously in a subsection of the forest since 1979 (Petty , Petty et al , Hoy et al ). The number of occupied sparrowhawk territories in a subsection of the study area has been recorded since 1974 (Petty , Petty et al ).…”

Section: Methodsmentioning

confidence: 99%

Density‐dependent increase in superpredation linked to food limitation in a recovering population of northern goshawks Accipiter gentilis

Hoy

Millon

Whitfield³

et al. 2017

Journal of Avian Biology

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16A better understanding of the mechanisms driving superpredation, the killing of smaller 17 mesopredators by larger apex predators, is important because of the crucial role superpredation 18 can play in structuring communities and because it often involves species of conservation 19 concern. Here we document how the extent of superpredation changed over time, and assessed 20 the impact of such temporal variation on local mesopredator populations using 40 years of 21 dietary data collected from a recovering population of northern goshawks (Accipiter gentilis), 22 an archetypical avian superpredator. We then assessed which mechanisms were driving 23 variation in superpredation, e.g., was it opportunistic, a response to food becoming limited (due 24 to declines in preferred prey) or to reduce competition. Raptors comprised 8% of goshawk diet 25 on average in years when goshawk abundance was high, which is higher than reported

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Numbers, breeding performance, and diet of the sparrowhawk Accipiter nisus and merlin Falco columbarius in relation to cone crops and seed-eating finches

Cited by 35 publications

References 20 publications

Effects of temporal and spatial variations in food supply on the space and habitat use of red squirrels (Sciurus vulgaris L.)

Effects of temporal and spatial variations in food supply on the space and habitat use of red squirrels (Sciurus vulgaris L.)

Diet of tawny owls (Strix aluco) in relation to field vole (Microtus agrestis) abundance in a conifer forest in northern England

Density‐dependent increase in superpredation linked to food limitation in a recovering population of northern goshawks Accipiter gentilis

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