New Publication on population dynamics of Audouin's Gull !

Genovart, M., Oro, D. and Tenan, S. 2018. Immature survival, fertility, and density dependence drive global population dynamics in a long‐lived species. Ecology, https://doi.org/10.1002/ecy.2515

Abstract: Disentangling the influence of demographic parameters and the role of density dependence on species’ population dynamics is a challenge, especially when fractions of the population are unobservable. Additionally, due to the difficulty of gathering data at large spatial scales, most studies ignore the global dynamic of a species, which would integrate local heterogeneity dynamics and remove the noise of dispersal. We developed an integrated population model (IPM) at a global scale to disentangle the main demographic drivers of population dynamics in a long‐lived species.

We used 28 yr of Audouin's Gull demographic data encompassing 69 local patches (comprising 90% of the world population). Importantly, we took into account the unobservable fraction of non‐breeders and also assessed the strength of density dependence for this fraction of the population. As predicted by life histories of long‐lived organisms, temporal random variation in survival was highest for immature individuals (1.326, 95% credible interval [CRI] 1.290–1.940) and lowest for adults (0.499, 95% CRI 0.487–0.720). Large temporal fluctuations in the probability of taking a reproductive sabbatical would partly explain the consistency in adult survival, with individuals most likely refraining from breeding when environmental conditions were harsh. Immature survival and fertility were the main drivers of population dynamics during the study period (r² = 0.83, 0.77–0.87 and 0.73, 0.63–0.79, respectively). We found strong evidence of density dependence, not only due to the number of breeders (r² = −0.34, −0.43 to −0.24) but also due to individuals on sabbatical (r² = −0.18, −0.33 to −0.01). From a conservation point of view, the species shows a 5% annual global decrease during the last 10 years, and we propose an update of its conservation status. Even though population dynamics of long‐lived organisms are very sensitive to changes in adult survival, we show here that, in the absence of strong environmental perturbations affecting this vital rate, fluctuations in population density are mainly driven by variations in survival of immature individuals and fertility. Integrated models based on long‐term monitoring at a global scale may enhance our ecological and evolutionary understanding of how demographic drivers influence population dynamics.

GEDA at the Week of Science

This week the GEDA is taking part in the Week of  Science initiative at the IMEDEA. A speed-dating between students and researchers to talk about current scientific projects. Next date: Friday, 9h30 "Who has stolen my sandwich !?"

Recovering Shearwaters

Help to recover fledglings of Cory's shearwater attracted to land by the lights. If you find one on land call 112

New Publication on seabirds and fishery discards!

Real, E., Tavecchia, G., Genovart, M., Sanz-Aguilar, A., Payo-Payo, A. and Oro, D. 2018 Discard-ban policies can help improve our understanding of the ecological role of food availability to seabirds Scientia Marina. Special Issue. Discards regulation vs Mediterranean fisheries sustainability. M. Demestre and F. Maynou (eds.) doi: 10.3989/scimar.04746.10A

Abstract: Discards from fisheries are the most important predictable anthropogenic food subsidies (PAFS) that are being incorporated into marine ecosystems. Changes on their availability and predictability can help us to understand the role that food availability (i.e. an important indicator of the carrying capacity) plays at different ecological levels, from individual fitness to community dynamic and ecosystem functioning. For several reasons, seabirds are an excellent model for

Photo: J. Bos

evaluating the ecological effects arising from a lack of discards: 1) they are one of the most important discard scavengers, 2) they are easy to monitor and 3) they are apical predators are globally distributed, which makes them suitable health indicators of ecosystems. Here we review the existing information on seabird-discard interactions to identify the main knowledge gaps and propose new challenges for improving our understanding of the general role of food availability. We conclude that the new policies on the ban of fishery discards that are being progressively implemented in the European Union, Norway, Chile and New Zealand offer a suitable experimental scenario for improving our understanding of how a large decrease in the carrying capacity may alter demographic parameters such as survival, dispersal and reproduction, the resilience of populations against perturbations and the role of individual specialization in the foraging process.

GEDA at the 14th International Seabird Group Conference

A. Sanz-Aguilar and A. Payo Payo presented their work this week at the 14th International Seabird Group Conference held in Liverpool (schedule here). The talk by A Sanz-Aguilar was an invited plenary and the one by A. Payo Payo on the effect of PAFS on synchrony has been awarded with the third prize for the best talked presented. Congratulation Ana(s)!

Mosquitos on the News !

The study by the GEDA on the tiger mosquito went on the local news here 

New Publication on Tiger Mosquito presence !

Sanz-Aguilar, A., Rosselló, R, Bengoa, M, Ruiz-Pérez, M., Barceló, C., Borrás, D., Paredes-Esquivel, C., Miranda, M.-A. and Tavecchia, G., 2018. Water associated with residential areas and tourist resorts is the key predictor of Asian tiger mosquito presence on a Mediterranean island. Medical and Veterinary Entomology, doi: https://doi.org/10.1111/mve.12317

 

Abstract: The Asian tiger mosquito, Aedes albopictus (Diptera: Culicidae), is a highly invasive species and a vector of several viruses of serious concern to public health. Investigating the habitat selection of this species at small to medium scales is essential to the planning of effective prevention and control campaigns.

The present group considered detailed data for this species' presence/absence collected at 228 sites on Mallorca Island (Spain) in autumn 2015, 3 years after the first detection of the species on the island. Site occupancy models accounting for false negative detections and imperfect monitoring were used to evaluate the relationships between mosquito presence and habitat variables. In the study area, mosquito presence was negatively associated with altitude, probably as a result of greater human presence at low altitudes near the coast. 

Moreover, the presence of Ae. albopictus was positively associated with swimming pools as a result of associated gardens, plants and sources of fresh water. These two variables were combined to predict the presence of the species across the entire island.

The publication has been noticed by many journals. You can find a press release in Spanish and the list of the other notes here

Caught on camera !

A previous work by Ana Sanz-Aguilar (here) has showed that a small number of highly specialized gulls was responsible for the observed predation at a colony of an European Storm Petrel. Selective culling directed to these individuals improved petrel breeding sucess and survival, an indication that massive culling plans might well miss the target. Ten years after, Ana found some new kids in town ... and this time she took them on camera!