CHAPTER 14 



THE FAUNA OF BIRDS' NESTS 



. . . this bird 

 Hath made his pendant bed and procreant cradle : 



Shakespeare 



Birds' nests, as Waterston remarked with masterly understatement, 

 must make lively nurseries. It is the really snug nests, built 

 under eaves or placed in holes, like those of martins and jackdaws, 

 which provide the offspring with an early insight into the grim realities 

 of life. Even migration must seem a picnic in comparison with the tor- 

 tures of nestling days. Young wood-pigeons, which squat precariously 

 on a flimsy raft high up in the branches, have a very easy time in com- 

 parison, and could well look back with nostalgic regret on the period 

 of pigeons' milk passed among the swaying tree tops. 



The inhabitants of birds' nests, other than the rightful owners, are 

 chiefly arthropods. Insects and mites predominate, although ticks, 

 pseudo-scorpions, spiders and an occasional centipede, wood-louse, or 

 free-living nematode may also be present. In Finland, Nordberg 

 studied the fauna of 56 species of birds' nests, from which he recorded 

 no less than 529 different kinds of arthropods. Beetles accounted for 

 118 species and mites another 228. The rest consisted of bugs, flies, 

 fleas, ticks, feather lice, moths, springtails, earwigs, book-lice and a few 

 parasitic Hymenoptera and spiders. A number of permanent obligate 

 ecto-parasites, such as the feather lice, occasionally wander off the host, 

 possibly in the process of transferring themselves to the nestlings, and 

 are found in the nest, but they are not true nidicoles, as their proper 

 habitat is the host's body. In addition, about a third of the species 

 found in birds' nests are purely casual or accidental visitors. Another 

 large category includes species which frequent various micro-habitats 

 that afford conditions similar to those of nests. Thus many beetles which 



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