Zum Verhalten spanischer Geier an Kadavern

König, Claus

doi:10.1007/bf01644326

Cited by 25 publications

(17 citation statements)

References 6 publications

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“…Some species are specialized carrion consumers (i.e., obligate scavengers, the Gyps vultures) and others are opportunistic-facultative scavengers . Facilitatory processes have been proposed to follow two opposite paths within this guild: small-body-sized scavengers landing earlier at carcasses would increase the chances of carcass detection by larger vultures (local enhancement) and large vultures would dismember the carcass (something smaller scavengers cannot do) thus allowing smaller scavengers to profit from the resource (trophic advantage; Kruuk 1967, Ko¨nig 1974, 1983.…”

Section: Introductionmentioning

confidence: 99%

Resource unpredictability promotes species diversity and coexistence in an avian scavenger guild: a field experiment

Cortés‐Avizanda

Jovani

Carrete

et al. 2012

Ecology

142

144

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Abstract. Chance per se plays a key role in ecology and evolution, e.g., genetic mutation, resource spatiotemporal unpredictability. In community ecology, chance is recognized as a key factor in community assemblage, but less is known about its role in intraguild processes leading to species coexistence. Here we study the relevance of resource unpredictability per se as a promoter of intraguild positive interspecific interactions and as a biodiversity enhancer in an Old World avian scavenger guild, which has evolved to feed upon spatially and temporally unpredictable resources, i.e., carcasses. We performed a large-scale field experiment in which 58 carcasses were disposed of and observed until complete consumption, either in continuously active supplementary feeding stations (predictable carcasses) or disposed of at random in the field (unpredictable carcasses). Richness of scavenger species was similar at unpredictable and predictable carcasses, but their relative abundances were highly uneven at predictable carcasses leading to higher scavenger diversity (Shannon index) at unpredictable carcasses. Facilitatory interspecific processes only occurred at unpredictable resources but were disrupted in predictable conditions because the dominant specialist species (in our case, the Griffon Vulture Gyps fulvus) arrived earlier and in larger numbers, monopolizing the resource. Small, endangered scavengers congregated at supplementary feeding stations but profited less compared to unpredictable carcasses, suggesting that they could constitute an ecological trap. Our findings offer new insights into the relevance of unpredictability of trophic resources in promoting both positive facilitatory interspecific interactions and species diversity and thus maintaining the function of guilds. Finally, the preservation of randomness in resource availability and the processes associated with its exploitation should be a major goal of conservation strategies aimed to preserve scavenger guilds evolved under naturally unpredictable trophic resources.

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Section: Introductionmentioning

confidence: 99%

Resource unpredictability promotes species diversity and coexistence in an avian scavenger guild: a field experiment

Cortés‐Avizanda

Jovani

Carrete

et al. 2012

Ecology

142

144

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“…Studies on the foraging behaviour of the Eurasian griffons Gyps fulvus are comparatively few (Ko¨nig 1974, Bahat & Kaplan 1995, Bo¨gel 1999, Bahat 2007) although the species is rather common in the western Palearctic (Birdlife International 2004), and well adapted to the rural activities of man (Cramp & Simmons 1980, Houston 1996.…”

mentioning

confidence: 98%

Foraging Behaviour and Flight Characteristics of Eurasian Griffons Gyps fulvus in the Island of Crete, Greece

Xirouchakis

Andreou

2009

Wildlife Biology

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We studied the foraging behaviour of Eurasian griffons Gyps fulvus on the island of Crete during 1997–2005 by direct observations in four colonies and by monitoring the movements of seven radio‐equipped individuals. The estimated foraging range of griffon colonies, based on direct observations, ranged from 206–851 km2 by using the Minimum Convex Polygon method, and 195–527 km2 by using the Adaptive Kernel method, with corresponding means of 472 and 380 km2, respectively. Meanwhile, radio‐tracking showed that foraging vultures covered an area ranging from 390–1300 km2. The mean foraging radius was calculated at ca 15 km and the mean maximum one at 29.9 km. On windless days, griffons' mean cross‐country speed was 5.1 m/second (maximum = 13.3 m/second), with a mean climbing rate of 0.6 m/second and a mean inter‐thermal gliding speed of 18.8 m/second. Any livestock carrion located up to 9 km from a colony was exploited by its members with minimum competition from individuals of adjacent areas. In total, we recorded 23 feeding incidences which took place at a mean distance of 8.4 km from the colonies. The food types identified were sheep carcasses located near stock‐farms and offal disposed in waste dumps in the vicinity of the colonies. On average, the griffons allocated 7.6 hour/day to food searching. This varied significantly between months and seasons. The shortest foraging time was recorded in December (6.4 hour/day) and the longest in June (9.3 hour/day). A significant difference of one hour after sunrise was detected in the departure time from the colony between seasons revealing that griffons departed earlier during winter trying to maintain their foraging budget within the available daytime limits.

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“…obs.). This behaviour could be a result of physical limitations affecting the exploitation of these food sources, as has been found for different species of vultures (Konig 1974, 1983, Alvarez et al 1976, Donkzar 1993. The consumption of livestock carrion does not seem to be related to the abundance of livestock, except for poultry.…”

Section: Diet and Food Availabilitymentioning

confidence: 97%

Geographic variation of the winter diet of the Red Kite Milvus milvus in the Iberian Peninsula

García

Viñuela

Sunyer

1998

Ibis

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This paper presents data on the winter diet of the Red Kite Milvus milvus in the Iberian Peninsula. The diet composition and its relationship with food abundance and habitat characteristics were studied in two areas (northern and southern plateaux) with different food availability and habitat composition. Red Kites showed a clear difference in diet between the two plateaux, with a higher consumption of carrion on the northern plateau and of game species on the southern plateau. Common Voles Microtus arvalis, despite being a very abundant prey on the northern plateau, did not appear in the diet in high numbers, but their frequency was related to the proportion of land occupied by nonirrigated (cereal) crops. High frequencies of "small" carrion (e.g. farmed Rabbits Oryctolugus cuniculus, poultry Gullus sp.) in the diet were correlated with a decrease in the trophic diversity which suggested an active choice of the food, at least in years with low vole densities. We suggest that the use of carrion is influenced not only by its abundance but by its availability to Red Kites. Refuse tips and muladares (dumps for dead livestock) and their management during the winter are important for the conservation of the species.

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Zum Verhalten spanischer Geier an Kadavern

Cited by 25 publications

References 6 publications

Resource unpredictability promotes species diversity and coexistence in an avian scavenger guild: a field experiment

Resource unpredictability promotes species diversity and coexistence in an avian scavenger guild: a field experiment

Foraging Behaviour and Flight Characteristics of Eurasian Griffons Gyps fulvus in the Island of Crete, Greece

Geographic variation of the winter diet of the Red Kite Milvus milvus in the Iberian Peninsula

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