Friday, 8 July 2022

GEDA-i at Cape Town!

Dr. A. Rotger was invited by the Centre for Statistics in Ecology, Environment and Conservation (SEEC) of Cape Town University to attend the International Statistical Ecology Conference conference in South Africa. It was a good occasion to illustrate his work on applied demography and introduce the research lines of the GEDA-i.

Wednesday, 8 June 2022

Press release on the European Storm Petrel!

Following the publication by Militao et al. here , the European Storm Petrel hits the news.  A new press release on the European Storm Petrel here. and on the local newspaper here


Wednesday, 1 June 2022

Press release on the Balearic Shearwater!

The campaign on the Balearic Shearwater at Sa Dragonera Natural Park has attracted the attention of the press. Here is a press note on a local newspaper on the collaborative study the GEDA-i, Irbi and Oxford University are conducting this year.



Friday, 27 May 2022

Press release on gulls !

A. Sanz-Aguilar and J.-M. Igual wrote a press release on why gulls can be seen inland. They took the oportunity to resume our 14-year study on the Yellow legged gull. Here




Tuesday, 24 May 2022

Shearwater 2022 campaign!

The shearwater campaign 2022 is on the starting blocks. Today the first visit.

Friday, 20 May 2022

New Publicatin on Storm Petrel wintering areas!

Militäo, T., Sanz-Aguilar, A., Rotger, A. and Ramos, R., 2022 Non-breeding distribution and at-sea activity patterns of the smallest European seabird, the European Storm Petrel (Hydrobates pelagicus). Ibis doi:

Abstract: Determining the non-breeding distribution and activity patterns of migratory animals is essential to understand the trade-offs across breeding, moulting and migratory periods and to evaluate the differential levels of exposure of these animals to threats throughout the year. By taking advantage of the current miniaturization of geolocators, during the breeding season of 2019, we deployed geolocators on 10 European Storm Petrels Hydrobates pelagicus breeding on Benidorm Island, Western Mediterranean, to determine the distribution and activity patterns of this small seabird species. Of the eight individuals that were recaptured with usable geolocation data, all individuals migrated to the North Atlantic Ocean, ranging between the Canary Islands and south of Iceland. They possibly take advantage of the more productive waters in the North Atlantic areas explored during the non-breeding period compared with the Western Mediterranean areas explored during the breeding period. 

Photo from

This migratory pattern contrasted with the partial migration described for individuals breeding in the Central Mediterranean. Tracked individuals were more synchronous in their prenuptial than in their postnuptial migratory phenology, probably due to a higher probability of breeding success related to earlier arrival to the breeding area. At-sea activity data indicated that individuals spent more time on the water at night (and especially on those nights around the new moon) during the first half of the non-breeding period (matching the dates of the moulting period of the species). Although birds may begin to moult their feathers while breeding, some seemed to overlap the moulting period with the postnuptial migration. Our results show that multi-colony studies are needed to understand the drivers of distinct migratory patterns at intra- and inter-population levels and how small migratory species trade-off the overlap of moult with other energetically demanding activities such as breeding or migrating.

Friday, 15 April 2022

One every thousand nests !

Photo by A. Sanz-Aguilar

We have probably measured eggs and the clutch size of more than one thousand nests since 2007, when we began monitoring  the Yellow legged gulls at the Natural Park of Sa Dragonera. This year, for the first time we found a nest with 5 eggs. Most likely a case of egg dumping. 

Happy easter!

Saturday, 9 April 2022

New publication on marine Turtles!

Heredero Saura, L., Jáñez-Escalada, L., López Navas, J., Cordero, K. and Santidrian Tomillo, P. 2022 Nest-site selection influences offspring sex ratio in green turtles, a species with temperature-dependent sex determinationClimatic Change 170, 39 (2022). DOI: 10.1007/s10584-022-03325-y

 Abstract: Climate change threatens species with temperature-dependent sex determination as further warming could result in extremely biased sex ratios or offspring of only one sex. Among the possible adaptations of sea turtles to climate change, are behavioral responses toward nesting in cooler areas. We analyzed nesting patterns of East Pacific green turtles (Chelonia mydas) in Costa Rica to determine the occurrence of nest-site selection and how this could influence primary sex ratios (PSR). Green turtles exhibited nest-site repeatability. Nests placed by the same individual were generally closer (mean distance: 237.4 m) than other nests on the beach (mean distance: 411.0 m) and this repeatability was maintained in different nesting seasons. 

Photo from

Additionally, turtles tended to place late nests closer to each other than their early nests, suggesting an adjusting nesting behavior throughout the nesting season. A great majority of nests were placed in the vegetation (80.9%) and within this zone, turtles preferred nesting under trees (78%) than in grass areas (28%), where temperatures were cooler and PSR were less female biased. Mean nest temperature (°C) during the thermosensitive period and mean PSR were 30.7 ± 1.2 °C and 79 ± 4%, respectively. Most years were female-biased or extremely female-biased but there was approximately one male-biased year in the decade. Although many nests produced 100% females, some male hatchlings were produced every year, even during the extreme 2015–2016 El Niño event. The preference of green turtles for nesting in shaded areas could help to mitigate the negative impacts of climate change unless temperatures in shaded areas rose above the male producing temperatures.

 Press releases in Spanish here and here



GEDA-i at Cape Town!

Dr. A. Rotger was invited by the Centre for Statistics in Ecology, Environment and Conservation ( SEEC ) of Cape Town University to attend t...