Tuesday, 22 February 2011

WINTERING QUAIL: A MUDDY PICTURE

The Common Quail (Coturnix coturnix) is a highly mobile species, especially the males, which move around at random in the breeding season in search of females. This mobility is the response to a complex reproduction system, without territory, and their particular breeding habitat, unirrigated cropland, which often changes its position from one season or year to another. Quails in fact may well breed more than once a year in Europe, first in the south and then further north. When the cereal crop is harvested they are forced to move anew; on the Iberian Peninsula they usually congregate in the meseta norte, where the crop is harvested latest in the year. Lastly, come autumn, they move off to Africa. Not all of them, however; a few wintering birds do stay behind. For example during the field work of the Atlas of Wintering Birds in Spain there were 112 contacts over three winters (2007-2010), 31 of them in Extremadura; Badajoz is the Spanish province with most wintering Quails (22 contacts). The provisional map below shows the places where these wintering Quails were found (sampled grids shown in red, grids with wintering quail shown in blue).

But a curious event begs new questions. On 04/12/2010 in Navalvillar de Pela (Badajoz) a hunter was seen carrying a shot Quail (S. Mayordomo, C. Clemente and J. Mahíllo). Nothing extraordinary about this because Quail are known to winter here sometimes. A few days later, on 20/12/2010, three people were seen releasing Quail in another part of the same area, three complete crates of birds; they then started shooting at them forthwith, killing at least six (Á. Sánchez). This unexpected event, perhaps a one-off, poses doubts about whether the wintering Quail are natural. We know for sure only about this one case of deliberate Quail release in winter and winter Quail observations are fairly widespread, so the logical conclusion to draw is that wild birds do winter. This is borne out by studies conducted in Portugal which show the presence of migratory birds from September to December and sedentary birds from December to March, when the first migrants return from Africa. The proportion of migrants, judging from body fat, peaks in October (40-50%) and there are always more migrants in the north than in the south, where up to 70% of the birds are non migrators. Autumn density is usually high, up to 130 Quails per km2. Sedentary birds start breeding very early in the year, singing as from November and pairing off as from December. They breed before the migratory birds and the first brood is itself able to breed after a few months in their first summer. This sedentary behaviour seems to be recent, as the result of changes in farming practices. Although Portuguese authors argue that the same thing happens in north Africa and part of Spain, including Extremadura, there is no actual information to confirm this. In fact there are no known records of singing Quail in Extremadura in December or January (the first are heard in February) and winter records, even allowing for the specie's retiring habits and low detectability, are still few and far between (only nine from 2005 to 2008).

Sources:

- Catry, P., Costa, H., Elias, G., and Matias, R. 2010. Aves de Portugal. Ornitologia do territorio continental. Assirio & Alvin. Lisbon.
- Anuarios Ornitológicos de Extremadura (Aves de Extremadura) 1998-2008.