The Use of Spider Silk in the Nests of Small Birds, With Particular Reference to the Chaffinch (Fringilla coelebs)

Storer, Nicholas P (1991) The Use of Spider Silk in the Nests of Small Birds, With Particular Reference to the Chaffinch (Fringilla coelebs). MSc(R) thesis, University of Glasgow.

Abstract

A very wide range of smaller passerine birds employ silk, from spiders and other arthropods, as a nesting material. The nest is an important feature of bird breeding behaviour, success being dependent in part upon the structure of the nest and the timing of construction of the nest. Spiders can spin many different types of silk, with varying properties, but all spider silks are remarkably strong and extensible. In addition, web silk is adhesive and represents a renewable resource. This study has shown that the chaffinch uses spider web and cocoon silk. Cocoon silk attaches lichen to the outside of the nest, and holds together the moss structure. Web silk is used in more general roles, and usually to a lesser extent; it appears to be an all purpose bonding material, attaching a range of materials to the outside of the nest, and binding together other structural materials. Web silk is also used to attach the nest to the twigs of the bush or tree in which it is built. Using scanning electron microscopy, it has not been possible to identify with any certainty the spider families which spin the cocoon silk used, but all web silk found in chaffinch nests appears to belong to the family Amaurobiidae. These webs are spun flat against rough tree bark and on fences etc. , and trap insects by entangling them in extremely fine fibrils. The amount of this silk present at Garscube Estate, on the edge of Glasgow, starts to rise just before the onset of chaffinch nest building. It is proposed that nest-building is not restricted in location by the availability of this common silk-type, but the birds may be prevented from building earlier in the season by a lack of these webs in the environment. However, the use of silk appears to enable them to breed in areas where the sites and materials available for nest-building are not ideal. It may be possible to generalise these findings for the chaffinch to other temperate, and tropical, passerines that employ silk as a nesting material. Compared with chaffinch nests, the extent of silk usage can be far greater, and the number of functions it fulfils far wider, in nests of other birds. The birds may consequently find themselves more restricted in time and place of breeding where the types of silk needed are not in abundance.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Zoology, Ecology
• Date of Award: 1991
• Depositing User: Enlighten Team
• Unique ID: glathesis:1991-78356
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Feb 2020 12:09
• Last Modified: 28 Feb 2020 12:09
• URI: https://theses.gla.ac.uk/id/eprint/78356