BIJLSMA RG & DIERMEN J VAN (1986) The Bobby Falco subbuteo as a breeding bird on the Dutch Wadden Sea Islands. LIMOSA 59 (3): 135-137.

Eurasian Hobby Falco subbuteo A description is given on the recent development of viable Hobby populations on several Dutch Wadden Sea Islands (fig. 1). The increase on Texel and the very recent settlement on Vlieland and Terschelling coincided with an increase in the breeding population of the Carrion Crow Corvus carone, the main supplier of nests for Hobbies in the Netherlands. The variety of food on Vlieland and Engelsmanplaat suggests that the species is capable of catching enough prey on the islands, both when breeding and summering (tab. 1). Prey selection is highly opportunistic. The breeding biology was studied on Texel during 1966-85. Mean clutch size was 3.1 (1 x 2,22 x 3, and 4 x 4). Brood size was as follows: 5 x 1, 4 x 2, 16 x 3, and 3 x 4 young per brood (mean = 2.6). One c/2 resulted in one fledgling, 19 c/3 in 36 fledglings (63%), and three c/4 in 12 fledglings (100%). Overall breeding success, expressed as a percentage of fledglings related to the number of eggs laid, was 69% (n = 23). Hobbies on Vlieland and Terschelling also reared young successfully.

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