Nestwatch 2010

Nest Watch 2010 aims to collect 2010 Nest Record Cards for Blackbirds and Song Thrushes during the 2009/1010 breeding season. Both species occur throughout the country (see Atlas maps on pages 254-257) so every member should be able to contribute - you shouldn’t need to go further than your garden or local park. If every member contributes just 2 cards we can reach our target!!

Why study Blackbirds and Song Thrushes?

We want to collect sufficient records to allow us to compare aspects of breeding biology throughout the country. Earlier studies (in the 1940s and 1960s) indicated that Blackbirds started breeding later at St Arnaud, Nelson than those in Auckland, but that there was very little difference in Song Thrushes. Does the same hold true today?

Global climate change is already impacting the timing of breeding of some species in the northern hemisphere, but at present there is little information available for New Zealand, apart from a long-term study of Starlings at Lower Hutt which suggested that ‘laying dates varied with food availability which fluctuated according to climatic events’.

Separating the nests

Both Blackbirds and Song Thrushes build relatively large, bulky nests, that of the Blackbird being the larger. Nests usually are made of grass, plant stems, dead leaves, thin twigs and roots. Song Thrush nests may also contain moss and lichen. The Song Thrush nest is lined with a smooth layer of mud or rotten wood pulp, whereas the Blackbird usually incorporates some mud in the nest cup, but lines the nest with fine grass, pine needles and dead leaves.

Separating the eggs

• Blackbird:
  light blue covered with fine reddish-brown speckling and mottling.
  

• Song Thrush:
  bright, light blue with a small number of black or purple-brown spots, speckles or small blotches.
  

Nest Record Cards are available from your RR or can be downloaded here.

Further reading

• Bull, P.C. 1946. Notes on the breeding cycle of the Thrush and Blackbird in New Zealand. Emu 46: 198-208.
• *Flux 1966. Breeding of Song Thrushes and Blackbirds at St. Arnaud, Nelson. Notornis 13: 142-149
• Gurr, L. 1954. A study of the blackbird Turdus merula in New Zealand. Ibis 96: 225–261
• Kikkawa, J. 1966. Population distribution of land birds in temperate rainforest of Southern New Zealand. Trans. R. Soc. N.Z. (Zool.) 7: 215-277.
• Marples, B.J. & Gurr, L. 1943. Emu 43: 67-71.
• *McKenzie, H.R. 1945. A Blackbird nesting story.NZ Bird Notes 1: 110-112.
• *Tily, I. 1946. The nesting activities of a pair of Blackbirds. NZ Bird Notes 1: 117-120.
• Tryjanowski et al. 2006. Date of breeding of the starling Sturnus vulgaris in New Zealand is related to El Niño Southern Oscillation. Austral Ecology 31: 634-637.

* Papers can be downloaded from our Notornis site: http://www.notornis.org.nz/ FREE of charge!