GEDA at the VII Conference on Balearic Environment

 The GEDA participated at the VII Balearic Environmental Conference on Mallorca and Ibiza presenting the studies on lizards, vultures, shearwaters and storm petrels.

 

New Publication on modelling transient probability!

Sanz-Aguilar, A., Pradel, R. and Tavecchia, G. 2018 Age-dependent capture-recapture models and unequal time intervals. Animal Biodiversity and Conservation 42 (1), pag. 91-98  https://doi.org/10.32800/abc.2019.42.0091

Photo: M. Gomila

Abstract:Estimates of survival probabilities in natural populations can be obtained through capture–mark–recapture (CMR) models. However, when capture sessions are unevenly spaced, age–dependent models can lead to erroneous estimates of survival when individuals change age class during the time interval between two capture occasions.
We propose a solution to correct for the mismatch between time intervals and age class duration in two age class models. The solution can be implemented in different ways. The first consists of adding dummy occasions to the encounter histories and fixing the corresponding recapture probabilities at zero. The second makes use of the log–link function available in some CMR software (e.g. program MARK). We used simulated and real data to show that the proposed solution delivers unbiased estimates of age–dependent survival probabilities.

The VIII edition of the Workshop on CMRR analysis ended!

The VIII edition of the annual workshop on CAPTURE-MARK-RECAPTURE and RECOVERY analysis has ended last friday! Thanks for coming (although we have missed the very big shrimp :-) ! It has been great to have you all here at the IMEDEA and learn about dragon-flies, storks, cranes, swans, houbara bustard, audouin's gulls, penguins norway lobsters, black-tailed godwits, marking methods..etc.. and top of all, new exiting biological questions.  More next year!

 

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)!