Liminana R.,Institute Investigacion en Recursos Cinegeticos IREC |
Liminana R.,University of Alicante |
Garcia J.T.,Institute Investigacion en Recursos Cinegeticos IREC |
Gonzalez J.M.,Fundacion MIGRES |
And 10 more authors.
European Journal of Wildlife Research | Year: 2012
Natal dispersal is an important component of bird ecology, plays a key role in many ecological and evolutionary processes, and has important conservation implications. Nevertheless, detailed knowledge on natal dispersal is still lacking in many bird species, especially raptors. We review and compile existing information from five tagging programmes of juvenile Montagu's harriers (Circus pygargus) in different Spanish regions, with PVC rings or wing tags, to provide an assessment of philopatry and natal dispersal of the species in Spain. Only 7% of all tagged harriers were observed as breeders in subsequent years. The percentage of philopatric (i. e. breeding within 10 km of the natal site) males and females was lower that 5%. Overall, there were no sexual differences in percentage of philopatric birds or dispersal distances, but we found study area differences. The low philopatry observed suggests a high capacity for natal dispersal in this species, for both sexes, and therefore high genetic mixing between populations. Differences in philopatry between study areas may be influenced by the different observation effort or detectability, or else reflect different philopatric strategies among populations. Finally, we found no significant differences in philopatry rate or dispersal distances related to tagging method, suggesting that tagging technique has a smaller effect than monitoring effort or observation ease on observation probability. Developing tagging programmes at a small scale and without procuring very large-scale and intensive subsequent monitoring is not worthwhile for evaluating philopatry and natal dispersal in this species. © 2011 Springer-Verlag.
Zuberogoitia I.,Icarus |
De La Puente J.,Autonomous University of Madrid |
Elorriaga J.,Fundacion Migres |
Alonso R.,BRINZAL |
And 2 more authors.
Journal of Raptor Research | Year: 2013
Molt patterns are poorly understood in most large bird species; however, they are of paramount importance in the development of surveys in which age is a key parameter. From 2000 to 2011, we studied the body condition and molt patterns of 214 Griffon Vultures (Gyps fulvus) in Spain. Adult Griffon Vultures ("griffons") demonstrated a poor body condition in winter during the incubation period, which then improved after hatching. Conversely, subadults were fairly uniform throughout the year, with their condition slightly inferior to that of adults throughout the year (except during the incubation period). The molt period lasted from April to December, ending in winter. Juveniles started their first molt in May of their second calendar year, beginning from the innermost primary (pp1) and proceeding outwards. Later, in midsummer, some individuals molted secondaries (only 17% of secondaries were molted in the first molt season) beginning at four foci: from the innermost (ss25) outwards, the outermost (ss1) and ss5 or ss6 inwards, and centrifugally from ss12. In the third calendar year, griffons continued molting primaries outwards in an orderly fashion and two new foci appeared in secondaries, apparently at ss6 and ss15. Most juvenile feathers were completely molted by the fourth calendar year, although some fifth-calendar-year griffons had retained juvenile secondaries. Subsequently, adults did not show a consistent molt pattern, but had a high degree of asymmetry between the two wings. Some quills were molted more often than others and this led us to hypothesize that adult griffons might molt quills on demand. © 2013 The Raptor Research Foundation, Inc.
Zuberogoitia I.,Icarus |
Alonso R.,BRINZAL |
Palomares L.E.,BRINZAL |
Martinez J.A.,CSIC - Institute of Polymer Science and Technology
Journal of Raptor Research | Year: 2011
The sex determination of Eurasian Sparrowhawks (Accipiter nisus) is not apparently a problem, as sexual dimorphism seems to be evident, at least in adults. However, there is a clinal geographic variation expressed as increasing size and decreasing color saturation from west to east. Hence, in wintering regions such as the Iberian peninsula, where migrant birds headed toward Africa also occur, sedentary birds are mixed with migrant and wintering birds from September to April. Here, we would expect to find birds from different breeding areas and therefore, possessing notable differences in biometrics, body mass, or color. We trapped eighteen adult sparrowhawks during the breeding seasons between 2001 and 2007 in Bizkaia, northern Spain, and we measured 91 dead and 38 rehabilitated sparrowhawks from Spanish Wildlife Rehabilitation Centers (WRC) between 1999 and 2007. A total of 147 full-grown sparrowhawks were sexed, aged, and measured. Some overlap between sexes was found for all but four measurements (eighth primary length [P8], wingspan, forearm, and mass). Only bill length differed significantly between age classes (juvenile/adults) and wingspan differed between sedentary and wintering birds for both sexes. Three variables: bill length, forearm, and P8 were retained in the discriminant function, allowing us to determine the sex with 100% accuracy. It is possible to correctly sex sparrowhawks, both adults and juveniles, using the three measures, even when the origin of the bird is unknown. © 2011 The Raptor Research Foundation, Inc.