Sunday, July 12, 2020

Egg sizes in introduced birds

TitleEgg sizes in introduced birds
Publication TypeJournal Article
Year of Publication2007
AuthorsCassey, P
Type of Articleletter
Keywordsbrood parasitism, Chrysococcyx lucidus, Gerygone igata, Grey Warbler, nestling eviction, Shining Cuckoo

An editorial oversight prevented my being able to correct some minor errors in Flux’s (2006) interesting and informative response to our paper on the reduction in egg size in populations of exotic passerines in New Zealand. Specifically, despite the claim that the eggs were collected from 'an unspecified area', we clearly state in the reference from which the data were obtained (Cassey et al. 2005) that the eggs were collected in agricultural habitats at Benneydale in the Central North Island, and cited the map reference (175°22’ E, 38°32’ S).

I note also that our key variable of interest was average clutch volume, the product of egg volume consistent relationship, as might be inferred from Flux (2006), between average egg volume and clutch size between regions. However, I cannot help but agree that the much larger sample sizes available to Flux clearly cast considerable doubt on the generality of the relationship we derived and so I strongly encourage more studies that might further elucidate the mechanisms of the variability in reproductive output in exotic birds in New Zealand.

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