If you need an accessible version of this item please contact JSTOR User Support

Thrush Predation on the Snail Cepaea hortensis

C. B. Goodhart
Journal of Animal Ecology
Vol. 27, No. 1 (May, 1958), pp. 47-57
DOI: 10.2307/2173
Stable URL: http://www.jstor.org/stable/2173
Page Count: 11
  • Download PDF
  • Cite this Item

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support
Thrush Predation on the Snail Cepaea hortensis
Preview not available

Abstract

1. Shells of Cepaea hortensis eaten by song thrushes were collected from the same area every month for three years. 2. The birds fed on snails only during two restricted periods of the year, in January, February and March, and in June and July, with hardly any taken in between C. hortensis is probably not very palatable as food to thrushes and serves as an ecological reserve, being taken only when other food is short during cold weather in the winter, and in mid-summer after the spring flush of caterpillars and before there is much fruit available. 3. During the winter feeding period quite a high proportion of dead empty shells were taken by thrushes to their anvils. 4. There was evidence of a systematic seasonal change in the anvil sites. 5. Significantly more pink than yellow shells were taken by thrushes in the summer than in the winter feeding periods, but no differential predation of the various shell banding patterns could be observed. Various possible reasons for this differential predation are discussed, and it is concluded that visual selection by birds, rather than genetic differences in activity in the snails, provides the best explanation. This could be responsible for maintaining some `predation polymorphism' in the species, but the situation is a complex one and there are certainly other factors involved as well.

Page Thumbnails

  • Thumbnail: Page 
47
    47
  • Thumbnail: Page 
48
    48
  • Thumbnail: Page 
49
    49
  • Thumbnail: Page 
50
    50
  • Thumbnail: Page 
51
    51
  • Thumbnail: Page 
52
    52
  • Thumbnail: Page 
53
    53
  • Thumbnail: Page 
54
    54
  • Thumbnail: Page 
55
    55
  • Thumbnail: Page 
56
    56
  • Thumbnail: Page 
57
    57