Food Caching, Cache Recovery, and the Use of an Egg Shell Dump in Hooded Crows Corvus corone cornix

Fjeld, Per E.; Sonerud, Geir A.

doi:10.2307/3676720

Cited by 8 publications

(7 citation statements)

References 18 publications

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“…Because the number of scats of red foxes increased with distance from cabin areas, thus indicating no preferential activity near cabins in June and July, red fox was probably not the cause of the skewed nest predation pattern. Corvid birds usually remove all eggs from the nests (Fjeld and Sonerud 1988), like we found in our study. Thus, since the number of corvid birds increased closer to cabin areas, and eggs in artificial nests are robbed mainly by visually hunting predators (Storaas 1988;Willebrand and Marcström 1988), and corvid birds are known to be attracted to areas of human activity (Myrberget 1985;Storch and Leidenberger 2003;Watson and Moss 2008), we conclude that the higher nest predation near cabins was caused by corvid birds rather than by mammalian predators.…”

Section: Discussionmentioning

confidence: 64%

The effect of recreational homes on willow ptarmigan (Lagopus lagopus) in a mountain area of Norway

et al. 2010

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The increasing development of recreational resorts and second homes in mountain regions worldwide require substantial infrastructure, and have large impact on habitats and ecosystems. We hypothesized that developed areas would attract predators and lead to higher predation on willow ptarmigan and lower their abundance. In a 500-km 2 study area in south-central Norway, we sampled the density of territorial cocks in spring and the breeding success of willow ptarmigan along a 3-km gradient extending out from clusters of cabins. We also sampled red fox scats and corvid birds and measured nest predation on artificial nests across this gradient. Densities of cocks in the spring and of adults and brood sizes in August did not vary along the gradient. However, the density of chicks in August was higher beyond 1.5 km from cabin areas, presumably because more hens lost their clutches in the vicinity of cabins. This was supported by the results from the artificial nest experiment where significantly more nests were depredated near cabin areas than further away. The number of scats of red fox along trails increased with distance from cabins, whereas more corvid birds were observed near cabins. We conclude that corvid birds were the main cause of higher loss of ptarmigan nests near cabin areas, which led to lower production of chicks. Breeding density, however, did not seem to vary along the gradient, presumably because of suitable habitat for breeding and little human activity in these areas during the period of pair formation and nesting.

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Section: Discussionmentioning

confidence: 64%

The effect of recreational homes on willow ptarmigan (Lagopus lagopus) in a mountain area of Norway

et al. 2010

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“…It is difficult to identify predators on the basis of shell remains left at the predated wader nests, as often no signs remain (Green et al 1987, Bellebaum 2001. In our study on wader population ecology, the only 'evidence' for corvid predation on wader nests was so-called shell dumps (see Loman & Göransson 1978, Fjeld & Sonerud 1988, occasionally found near crow nests in the area. Among others, these contain remains of eggs of waders, e.g.…”

mentioning

confidence: 75%

Response of Hooded Crow Corvus corone cornix and Magpie Pica pica to exposure to artificial nests

Olsen¹,

Schmidt²

2004

Bird Study

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“…Human‐generated resources are probably more predictable than natural ones. (5) As an alternative to energy storage, Hooded Crows can occasionally hoard food and use these reserves when food is not available (Fjeld & Sonerud 1988); thus in this species, the costs of fattening (Lima 1986, McNamara & Houston 1990) could outweigh the benefits.…”

Section: Discussionmentioning

confidence: 99%

Effects of food abundance and predictability on body condition and health parameters: experimental tests with the Hooded Crow

Acquarone

Cucco

Cauli

et al. 2002

Ibis

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It has been shown that small passerines can counteract variability of food resources by actively regulating their body reserves through an increase of mass. However, the effects of food predictability on body mass regulation and other body parameters, such as immune functions, in larger species have been little studied. To analyse the response of the Hooded Crow Corvus corone to food abundance and predictability, we performed three experiments with controlled food provisioning under laboratory conditions. Body mass, TOBEC (total body electrical conductivity) lean mass index, blood parameters and immune organ masses were measured at the beginning and end of a 15‐day period. In the first experiment, the food release was predictable (same amount each day) but the quantity of food delivered to five groups of birds varied (37, 75, 100, 150 or 300 g/day). Low food levels induced a greater decrease in mass accompanied by an increase in erythrocyte sedimentation rate. In the second experiment, the same average quantity of food (100 g) was supplied according to either predictable or unpredictable (random) schedules. In this case, the crows lost more mass, and their erythrocyte sedimentation rate increased when food was unpredictable. In the third experiment, the same average quantity of food (150 g) was supplied according to either a predictable schedule or two schedules with different levels of variability. The group with a low level of variability did not differ from the control, while the group with a highly variable feeding schedule lost more mass. In this group, the higher mass loss was associated with greater variation of the erythrocyte sedimentation rate and a reduced Phytohaemagglutinin index of immunocompetence and haematocrit value. The results of experiments 2 and 3 contrast with findings in other passerines, which increase their mass when food availability is unpredictable. It appears that a body mass decrease in the Hooded Crow can be induced by a reduction of either food abundance (exp. 1) or food predictability (exp. 2, 3), and it is accompanied by a worsening of health state.

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Food Caching, Cache Recovery, and the Use of an Egg Shell Dump in Hooded Crows Corvus corone cornix

Cited by 8 publications

References 18 publications

The effect of recreational homes on willow ptarmigan (Lagopus lagopus) in a mountain area of Norway

The effect of recreational homes on willow ptarmigan (Lagopus lagopus) in a mountain area of Norway

Response of Hooded Crow Corvus corone cornix and Magpie Pica pica to exposure to artificial nests

Effects of food abundance and predictability on body condition and health parameters: experimental tests with the Hooded Crow

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