European flyway permeability and abmigration in Teal Anas crecca, an analysis based on ringing recoveries

Abstract

Abmigration, the switch between flyways, is thought to be frequent in dabbling ducks, and supposedly results from high female philopatry combined with winter pairing: a male pairing in winter with a female from another flyway may follow her to her breeding area and thus abmigrate. On this basis, the frequency of abmigration should be much higher amongst males than amongst females, should increase with time since ringing, and be higher if environmental conditions force birds from different flyways into the same geographical area in winter (in this case the Iberian peninsula in the case of cold spells). Analysing more than 9000 recoveries of Teal ringed in the Camargue, southern France, showed that even with the most conservative flyway definition, 15% of Camargue (Mediterranean flyway) individuals (both males and females) were subsequently recovered in the North‐west European flyway. Moving a flyway boundary closer to the Camargue (i.e. to the south‐east) increased this percentage to c. 32%. None of the predicted patterns were supported by the data: there was no systematic sex difference in abmigration rate; abmigration showed no consistent increase with time from ringing, and was not significantly more frequent after cold spells. These results suggest that there is permeability between these two flyways for all classes of individuals, which might better be considered as a continuum. This should be taken into account in the development of management and conservation policies for Teal in Europe.

The Potential Distance of Highly Pathogenic Avian Influenza Virus Dispersal by Mallard, Common Teal and Eurasian Pochard

“…Thus, ducks from the Camargue can potentially infect major wetlands they use as wintering areas or as migratory stopovers, such as the Dombes (France), the Ebro delta (Spain), the Pô delta (Italy), and the alpine lakes (Switzerland). A similar pattern is expected if an outbreak occurs in another western Mediterranean wetland, because these lie within the same flyway as the Camargue (Guillemain et al, 2005). Consequently all wetlands around any site in the western Mediterranean area in which an outbreak occurs are potential high-risk areas at least during some parts of the wintering period.…”

Emigration rates and population turnover of teal Anas crecca in two major wetlands of western Europe

“…The Camargue is one of the most important wintering areas for waterfowl in the Black Sea/Mediterranean migratory flyway, where the number of teal counted annually ranges between 750,000 and 1,375,000 individuals (Scott & Rose 1996; note that the existence of two distinct flyways has been challenged by Guillemain et al 2005). The Vigueirat marshes are a protected area of 1,029 ha where up to 15,000 teals are counted (out of a total of about 38,000 in the Camargue).…”

Comparing the migration of Eurasian TealAnas creccafrom two main wintering areas of Western Europe: A long‐term study from Essex, England, and the Camargue, France

“…An earlier study showed that recoveries of Teal ringed in the Camargue could occur all over western, central and northern Europe (Guillemain et al 2005). This suggests that the split into distinct 'North-Western European' and 'Mediterranean' Teal subpopulations (eg Scott & Rose 1996) was artificial, and that all birds wintering in western Europe could therefore be considered to belong to a single larger population.…”

“…The present study also provides useful insights in the context of flyway delineation for this species. Indeed, we showed earlier (Guillemain et al 2005) that exchange rates between the so-called 'Mediterranean' and 'North-Western European' subpopulations reached 20% one year after ringing, making it doubtful whether birds from these two regions should really be split. The present observation that female Teal wintering in the two areas breed in the same geographic range strengthens the idea that there is only one Teal population in western Europe.…”

“…Thus, we expected that considering only intraannual ring recoveries could be a means of comparing spring migration processes from southern France and eastern England in this species. The analysis by Guillemain et al (2005) relied on the same Camargue data set as the present study; although that paper presented a map of all recoveries, it did not assess migration routes and distances, which is one of the purposes of the present report.…”