Information Distribution and the Growth of Economically Valuable Knowledge: A Rationale for Technological Infrastructure Policies

Abstract

(1) The nests (n=711) of twenty-four species of passerine birds were parasitized experimentally with model cuckoo eggs (2) Among current favourite hosts, species for which the cuckoo lays a mimetic egg discriminated against model eggs unlike their own (reed warbler, meadow pipit, pied wagtail), while the dunnock, which is not mimicked, did not discriminate. (3) Other species, suitable as hosts (intertebrate diet, accessible nests) but rarely used by cuckoos, showed just as much rejection of model eggs unlike their own (chaffinch, blackbird, song thrush), or stronger rejection (spotted flycatcher, reed bunting) than the most strongly rejecting of current favourite hosts. (4) Two results suggest that the egg discrimination by suitable hosts has evolved in response to cuckoo parasitism. (a) Species unsuitable as hosts (thus with no history of interaction with cuckoos) mainly showed little if any rejection of model eggs unlike their own than in Britain, where they are parasitized. (5) Species with smaller bills suffered greater rejection costs (own eggs damaged) and were more likely to reject model eggs by desertion than species with larger bills, which tended to reject by ejection. (6) Among species suitable as hosts, there was no tendency for smaller-billed species to reject less. Therefore rejection costs influenced the method of rejection but not rejection frequency.