Non-breeding Areas Research Articles

AFRICAN NON-BREEDING AREAS OF FENNOSCANDIAN OSPREYS PANDION HALIAETUS: A RING RECOVERY ANALYSIS

SUMMARY Saurola, P. 1994. African non-breeding areas of Fennoscandian Ospreys Pandion haliaetus: a ring recovery analysis. Ostrich 65:127-136. More than 36 000 Ospreys have been ringed in Fennoscandia up to 1992 and 638 of these have been reported from 30 different African countries. The recoveries suggest that adult and first-year Ospreys arrive in Northern Africa from earl September and cross the Sahara in late September to October. A record bird migrated 9817 km from Finland to South Africa in less than 40 days, at an average speed of more than 245 km/day. The majority of all age classes of Fennoscandian Ospreys spend December to February in equatorial Africa. The average compass heading from the different parts of the Fennoscandian breeding areas to the sub-Saharan non-breeding areas is roughly the same, ca. 206°. The longitude of the non-breeding area is dependent on the longitude of the breeding area. Western subpopulations spend their non-breeding period further to the west than more eastern subpop...

Current range and status of the Iberian lynx Felis pardina Temminck, 1824 in Spain

The current distribution of the Iberian lynx Felis pardina is outlined and its population size in Spain estimated at about 95% of its world range. There are 48 separate breeding areas, generally small in size. In addition, 32 non-breeding areas have been located, and 50 areas where lynx presence is uncertain, some associated with, and others separated from, breeding areas. A major part of the range supports low lynx densities. Range fragmentation is the most noteworthy feature of the distribution pattern, although dispersal might link some adjacent nuclei. Nine genetically isolated populations are recognized, although probably only two, accounting for about 70% of the total population, are viable in the short term. The Spanish population size is estimated at about 1100 individuals, with fewer than 350 reproductive females. The risks arising from this situation are analysed and conservation policies proposed.

Validity of Predictive Equations for Total Body Fat in Sanderlings from Different Nonbreeding Areas

We studied the validity of predictive equations for total body fat in shorebirds based on external morphology and body mass with data from Sanderlings (Calidris alba) collected in New Jersey, Texas, Panamá, and Perú. Equations derived at any one of these locations are not valid when applied to the other locations because changes in body mass involve both changes in fat and lean mass and because structural differences exist between these populations. We recommend that equations to predict total body fat in shorebirds derived at one location should not be applied to a different geographic area.

Unpredictable Habitats and Evolution of Bird Migration

In bird species living in areas where environmental stability and predictability is low, site fidelity is not an important factor in intraspecfic competition. If one part of a population of such a species evolves migratory behaviour (partly as a consequence of the lack of site fidelity), and if the productivity of this part of the population is higher than the productivity of the remaining part of the population, selection will favour migration. This leads to a situation where completely migratory land bird species originate from areas with a high environmental instability, like the dry woodland and savanna presently found in North and East Africa south of the Sahara, and the migration is directed towards those areas (higher latitudes) where environmental stability and production during the breeding season is higher than in the non-breeding areas (synchronization by a pulse climate). The migratory strategy is most fruitful for species with structurally simple niches, like waders, terns and swallows. Prerequisites are that there birds escape competition during the breeding season by migrating to marginal areas, and also that their productivity in the breeding areas is high enough to enable a sufficient number of young to return to the non-breeding areas and to compete successfully with the remaining part of the population.