martes, 27 de junio de 2017

Gull tracking on the news!

Photo: G. Tavecchia
GSM/GPS data are generating a growing interest in gulls' feeding strategy. A new article by E. Soto in the newspaper El Mundo (here) has just been published on the monitoring of Yellow-legged Gulls at Dragonera. Long-distance tracks and daily feeding strategies are on the spot. Thank also to the help of T. Muñoz from the GOB (Grup Balear d'Ornitologia I Defensa de la Naturalesa)

sábado, 24 de junio de 2017

Storm Petrel Days at Benidorm Island

The 29-30th of June the Natural Park of Sierra Gelada organizes the European Storm Petrel Day at Benidorm to mark the 25 years of populaiton monitoring. 
Special guest: Dr A. Sanz-Aguilar, who contributed to more than half of the period. 

martes, 20 de junio de 2017

New Publication on Spoonbill population dynamics!

Tenan S, Fasola M, Volponi S, Tavecchia G. Conspecific and not performance-based attraction on immigrants drivescolony growth in a waterbird. J Anim Ecol. 2017;00:1–8.

  1. Local recruitment and immigration play an important part in the dynamics and growth of animal populations. However, their estimation and incorporation into open population models is, in most cases, problematic. We studied factors affecting the growth of a recently established colony of Eurasian spoonbill (Platalea leucorodia) and assessed the contribution of local recruits, i.e. birds born in the colony, and immigrants, i.e. birds of unknown origin, to colony growth.
  2. We applied an integrated population model that accounts for uncertainty in breeding state assignment and merges population surveys, local fecundity and individual longitudinal data of breeding and non-breeding birds, to estimate demographic rates and the relative role of recruitment and immigration in driving the local dynamics. We also used this analytical framework to assess the degree of support for the ‘performance-based’ and ‘conspecific attraction’ hypotheses as possible mechanisms of colony growth.
  3. Among the demographic rates, only immigration was positively and significantly correlated with population growth rate. In addition, the number of immigrants settling in the colony was positively correlated with colony size in the previous and current year, but was not correlated with fecundity of the previous year.
  4. Our results suggest that the variation in immigration affected colony dynamics and that conspecific attraction likely triggered the relevant role of immigration in the growth of a recently formed waterbird colony, supporting the need of including immigration in population analysis.
You can see press release (in Italian) following the links belows:

miércoles, 14 de junio de 2017

The mistery of the route to the Cantabric Sea solved!

Tracking data offered a first breakthrough to solve the mystery of the route to the Cantabric Sea.   
Yellow-legged gulls from the Balearic islands have been regularly seen in the Cantabric coast, but the route to Northern Spain was a mystery. Do they fly around the Iberian peninsula or throught the Ebro valley ? Do they use the Ebro river as a landmark? Do they reach the Cantabric sea from France? 
Last year preliminary data provided a first piece of the puzzle when a gull moved North following the Ebro river to Zaragoza. However the radio failed at the end of the summer and the route to the Cantabric sea along the Ebro river was not proved. This summer tracking data deliver the solution to the mystery, showing what is likely to be the main route to the Cantabric Sea: the Ebro valley. Interestingly, the route seems to pass north of the river and through the Basque Mountains at Estella. To be continued....