New Publication on the rescue effect in Scopoli's Shearwaters !

Sanz-Aguilar, A.; Igual, J.M.; Tavecchia, G.; Genovart, M; Oro, D. 2016. When immigration mask threats: The rescue effect of a Scopoli’s shearwater colony in the Western Mediterranean as a case study. Biological Conservation, 198, 33–36. doi:10.1016/j.biocon.2016.03.034

Photo: M. Gomila

Abstract: Populations of long-lived species are highly sensitive to increases in mortality, but a loss of breeders can be compensated for by recruitment of local individuals or immigrants. Populations maintained through immigration can be sinks, jeopardizing the viability of the metapopulation in the long term when additive mortality from anthropogenic impacts occurs. Thus, the correct identification of whether a breeding population is maintained by local recruitment or by immigration is of special importance for conservation purposes. We developed robust population models to disentangle the importance of local recruitment and immigration in the dynamics of a Western Mediterranean population of Scopoli's shearwater Calonectris diomedea showing low adult survival but stable breeding numbers. Our results show that the shearwater population is not self-maintained but rescued by immigration: yearly immigrants recruiting in the population represents ~ 10–12% of total population size. We believe that this situation may be common to other Western Mediterranean populations, currently acting as sinks. We recommend urgent demographic studies at large core colonies to evaluate the global conservation status of the species.

 
A press release of the publication has just appeared. You can read the spanish version here

Stage at the G.E.P.

Julia Bos joined the GEP for her Erasmus+  stage.  She will be investigating the within-colony differences in egg volume, clutch size, movements and spatial structure of the Yellow Legged Gull at Dragonera Island. Welcome Julia.

New Publication on Indo-Pacific bottlenose dolphins !

Pérez-Jorge, S., Gomes, I., Hayes, K., Corti, G., Louzao, M., Genovart, M. and Oro, D. 2016 : Effects of nature-based tourism and environmental drivers on the demography of a small dolphin population Biological Conservation: doi:10.1016/j.biocon.2016.03.006

Abstract: Many marine top predators are experiencing significant declines due to anthropogenic impacts, and therefore reliable monitoring is essential to understand their population dynamics. We used Pollock's robust design capture–recapture modelling to assess the influence of oceanographic variables, artisanal fisheries and human disturbance on several demographic parameters (abundance, temporary emigration and survival) of the Indo-Pacific bottlenose dolphin (Tursiops aduncus), using long-term data on marked individuals from East Africa.

Photo-identification data was collected over 551 boat-based surveys between 2006 and 2009, with 137 individuals identified. Our best fitting model indicated that exposure to tourism (represented by the number of tourist boats) increased the probability of dolphins seasonally emigrating from the study area. The return rate of temporary emigrants was negatively linked to the seasonal sea surface temperature, probably associated with food availability. That model supported the existence of heterogeneity in annual local survival estimates, with transient dolphins showing a lower value than resident individuals (0.78 and 0.98, respectively). Furthermore, abundance estimates showed a small population size ranging from 19 individuals (95% CI: 11–33) to a maximum of 104 dolphins (95% CI: 78–139). This small population, together with their high site fidelity and coastal distribution, might be particularly vulnerable to human disturbances. This study highlights the influence of environmental and anthropogenic factors on dolphin demography and population dynamics and the need to integrate these drivers to provide robust evidences for conservation stakeholders in an adaptive management framework.

YLG 2016 campaign just started !

Photo F.Pezzo

The 2016 Yellow Legged Gull campaign has just started at Dragonera island. 
Birds are building their nests while few are already incubating. A good moment to read rings.

GEP on Media

The publication by M. Genovart on Balearic Shearwaters has reached the media !

Here a short television interview (Chapter 43/1, at min 24).  

A press release (in Spanish) here and a short note by the BBC Science & Environment here

New Publication on Storm Petrel Ecology!

Ramírez, F., Afan, I., Tavecchia, G., Catalán, I. A., Oro, D. and Sanz-Aguilar, A. 2016 Oceanographic drivers and mistiming processes shape breeding success in a seabird. Proceedings of the Royal Society B. Doi: 10.1098/rspb.2015.2287

Photo: M. Gomilla

Abstract: Understanding the processes driving seabirds' reproductive performance through trophic interactions requires the identification of seasonal pulses in marine productivity. We investigated the sequence of environmental and biological processes driving the reproductive phenology and performance of the storm petrel (Hydrobates pelagicus) in the Western Mediterranean. The enhanced light and nutrient availability at the onset of water stratification (late winter/early spring) resulted in annual consecutive peaks in relative abundance of phytoplankton, zooplankton and ichthyoplankton. The high energy-demanding period of egg production and chick rearing coincided with these successive pulses in food availability, pointing to a phenological adjustment to such seasonal patterns with important fitness consequences. Indeed, delayed reproduction with respect to the onset of water stratification resulted in both hatching and breeding failure. This pattern was observed at the population level, but also when confounding factors such as individuals' age or experience were also accounted for. We provide the first evidence of oceanographic drivers leading to the optimal time-window for reproduction in an inshore seabird at southern European latitudes, along with a suitable framework for assessing the impact of environmentally driven changes in marine productivity patterns in seabird performance.

Official press release (Spanish) here

New publication : Balearic Shearwaters still critically endangered

Genovart, M., Arcos, J.M, Álvarez, D., McMinn, M., Meier, R., Wynn, R.B., Guilford, T. and Oro, D., 2016 Demography of the critically endangered Balearic shearwater: the impact of fisheries and time to extinction. Journal of Applied Ecology. doi: 10.1111/1365-2664.12622

Abstract:

Photo: P. Arcos

1. World-wide, many seabirds are affected by fisheries in opposing ways: as a source of mortality from bycatch, but also by providing discards as a predictable and abundant food resource. This applies to the Balearic shearwater Puffinus mauretanicus, the most endangered European seabird, whose time to extinction was estimated at only ˜40 years a decade ago.
2. Since the previous assessment, new data and more sophisticated demographic modelling have become available, and new fishing policies from the European Union (Common Fisheries Policy, CFP) will apply, posing different scenarios for the viability of the species. Thus, there is both an urgent need and an opportunity for a more reliable update of the conservation status of the species.
3. Demographic data were collected between 1985 and 2014 at one of the world's largest colonies. Most demographic parameters were estimated using multievent capture–recapture modelling. Some parameters, such as bycatch rate, immature individual survival and recruitment, were estimated for the first time. We incorporated estimates into stochastic population models to forecast time to extinction and assess the viability under different management scenarios, accounting for upcoming fishing policies.
4. Adult survival was much lower than expected (0·809, SE: 0·013) and largely influenced by bycatch, which accounted for a minimum of 0·455 (SE: 0·230) of total mortality. Breeding success was positively correlated with discard availability. Recruitment started at low rates in 3-year-old birds (0·030, SE: 0·0455), increasing in following age classes and was almost complete at 6 years. Under the present scenario, we predict a time to extinction of 61 years (95% CI: 55–69).
5. Synthesis and applications. Population projections suggest that the actual impact of fisheries on Balearic shearwaters is unsustainable and the imminent discard ban under the new Common Fisheries Policy may accelerate the declining trend. This study demonstrates that reducing the bycatch rates of fisheries is an unavoidable and urgent conservation measure for avoiding the extinction of the species. We also advise setting up demographic long-term studies, to allow researchers to diagnose, with reliability, the effectiveness of management actions. These actions will also benefit many other marine top-predator species affected by this anthropogenic impact.

 You can read a press release here (Spanish)