The Tawny Owl by Jeff Martin

Author:Jeff Martin
Language: eng
Format: epub
ISBN: 9781472943583
Publisher: Bloomsbury Publishing
Published: 2022-01-15T00:00:00+00:00

Onset of breeding

There are differences of opinion when it comes to determining the onset of breeding. In Wytham Woods, Oxfordshire, for example, Southern (1970) was of the view that the start of breeding occurred with the beginning of incubation, and Petty (1992a) sympathised with that view because both of these researchers were concerned that nest visits during the egg-laying period might cause females to desert. These are valid arguments, although the onset of the breeding process might be deemed as starting in late October or early November. During this time the birds are relatively quiet although their presence can be detected on calm, still evenings shortly after dusk. Petty (1992a) drew attention to the territorial callings, which he reported commenced in late January through to early March, when the egg-laying period commences. Occasionally eggs are laid much earlier, and David Glue (2007) reported on Tawny Owl nests being started during the 2003 Christmas festive season, during the mildest winter for a decade.

However, in Bilbao, northern Spain, Iñigo Zuberogoitia (2002) found that the breeding period for Tawny Owls spanned a greater length of time than for other parts of Europe. He and his team further reported (Zuberogoitia et al. 2004) on a Tawny Owl study they were carrying out in the town of Mungia. In the corner of a park, a pair of owls bred in an oak tree which was cut down in 1997, when the owls were incubating four eggs. A nestbox was put up on another oak and broods of two were raised in the box in 1998 and 1999. In 2000, a nest with two owlets was found in the hole of a neighbouring oak. On 1 February 2001, two owlets were ringed in the same place; these chicks were 25 days old, which suggests that the first egg was laid some time in early to mid-December. Based on the findings of Zuberogoitia (2002) a mean laying date of 24 March was extracted from the findings of 126 Tawny Owl nests in Bilbao.

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