The food spectrum of sparrowhawk (Accipiter nisus L.) and kestrel (Falco tinnunculus L.) in the Chřiby Upland

Abstract

TOMEŠEK, M., ČERMÁK, P.: The food spectrum of sparrowhawk (Accipiter nisus L.) and kestrel (Falco tinnunculus L.) in the Chřiby Upland. Acta univ. agric. et silvic. Mendel. Brun., 2009, LVII, No. 2, pp. 145-150 In 2006-2008, mapping the sparrowhawk (Accipiter nisus L.) and kestrel (Falco tinnunculus L.) occurred in the SE part of the Chřiby Upland. At the same time, the food spectrum of these birds of prey was determined during nesting periods. The area under monitoring represented about 25-30 km 2 . In each of the species, food was always monitored in a period from February to July at four nesting localities. The food spectrum was analysed by the direct observation of birds of prey, according to le overs of food in the surroundings of nests and in nests of the predators. In Accipiter nisus, the food spectrum consisted of birds (85 %), mammals (3 %) and other animals (12 %). Turdus merula was the most frequent prey. In Falco tinnunculus, the food spectrum consisted of birds (18 %), mammals (76 %) and other animals (6 %). Microtus arvalis was unambiguously the most frequent prey. Accipiter nisus, Falco tinnunculus, food spectrumThis paper deals with the food spectrum of two bird of prey species living in the hilly agriculturalforest country of the Chřiby Upland, namely sparrowhawk (Accipiter nisus L.) and kestrel (Falco tinnunculus L.). Both predators are virtually of the same size but diff er in their nesting bionomy and food. In recent years, populations of both species show stabilized and slightly increasing character in the CR a er declines in the eighties. Nevertheless, detailed fi ndings on the food spectrum are virtually insuffi cient. Literature sources on the food ecology of these preda tors are rather obsolete (particularly as for sparrowhawk). Farský (1928) and Sládek (1963) dealt with the food of sparrowhawk and kestrel in our country. MATERIALS AND METHODSThe food composition of feathered birds of prey can be determined by various methods (Mlíkovský, 1998). Since the studied nesting localities were known very well the method of direct monitoring could be used. Particular nesting localities were monitored in regular intervals. The monitoring was always carried out in suffi cient distance and safe hiding place for birds not to be disturbed in no way. Conventional binoculars were used for monitoring. Although it is possible to determine some types of prey very well as well as what the predator subsequently does with the prey, this method is considerably time-consuming and includes always only certain part of the food spectrum and in many cases even not quite exactly. Therefore, analyses of le overs of prey were par ticu lar ly used. Not-swallowed le overs of prey were determined in the period of nesting right in nests, in places of the regular processing of food, such as tear-off stumps in sparrowhawks, places under trees in kestrels, where the prey is swallowed or at least partly processed. Food residues were collected and subsequently determined with a certain periodicity. Easily detecta...