Real, E., Oro, D., Martinez-Abrain, A., Igual, J.-M., Bertolero, A., Bosch, M.and Tavecchia, G., 2017.
Predictable anthropogenic food subsidies, density-dependence and socio-economic factors influence breeding investment in a generalist seabird Journal of Avian Biology,
48: 001–009
doi: 10.1111/jav.01454
Abstact: Recent European policies on the ban of fishing discards and the closure
of open-air landfills are expected to reduce predictable and abundant
food resources for generalist seabirds. In order to forecast the
consequences of this reduction on seabird breeding investment it is
important to understand whether diverse anthropogenic foraging resources
act synergistically or not and whether their influence is mediated by
density-dependent mechanisms.
To assess these effects at large
spatio-temporal scale, we measured mean egg volume as a proxy of
breeding investment in ca 5000 three-egg clutches of the yellow-legged
gull Larus michahellis from 20 colonies of the Western
Mediterranean, located both along European and African coasts. In
European gull colonies, egg volume increased with the availability of
fishing discards and landfills in the vicinity of the colony. However,
the landfill effect was weaker than the effect of fishing discards,
probably due to the lower quality of waste as food for gulls. In
contrast, none of the anthropogenic food subsidies influenced egg volume
in African colonies, likely due to socio-economic differences (i.e. a
much lower availability and predictability of both discards and waste
food. Finally, results showed that the positive association between
fishing discards and open-air landfills on egg volume was mediated by
negative density-dependent mechanisms probably related to an increase in
competition for food.
The Workshop on capture-mark-recapture-recovery analyses has ended. It has been very interesting to know abut new exciting systems, marking methods, ecological questions and above all to meet new colleagues. We learned about turtles, shearwaters, voles, goose, vulture, penn shells..etc.. 
A Yellow-legged gull equipped this spring with a GSM/GPS radio came back to the Balearic Islands after summering in Portugal ! (see photo by J. Marques) ...and it did so passing by Madrid !!!
Abstact: Recent European policies on the ban of fishing discards and the closure
of open-air landfills are expected to reduce predictable and abundant
food resources for generalist seabirds. In order to forecast the
consequences of this reduction on seabird breeding investment it is
important to understand whether diverse anthropogenic foraging resources
act synergistically or not and whether their influence is mediated by
density-dependent mechanisms.
Jaume Badia is joining the GEP for his Master’s degree project in Animal Ecology at the University of Lund, Sweden. Jaume work will focus on the conservation maeasures to protect the Egyptian Vulture at Fuerteventura (Canary Islands) under the direction of Ana Sanz-Aguilar and in collaboration with the Estacion Biologica e Doñana (CSIC).
With
the present rate of biodiversity loss and the profound effects of global
changes, population and conservation ecologists face new questions. Many of these are related to
how fast individuals can adapt to the strength and pace of environmental
variability and can only be answered using individual data collected over
long-term (Long Terms Individual Based Studies). Beside
this undoubted scientific value, a 20 – 30 years study is likely to have trained several
generations of scientists, fostered collaborations between a large number of
research institutes and promoted public awareness on scientific themes and
wildlife conservation problems. With
current public systems providing funds for 3 to 4 years, it is increasingly
difficult to initiate and maintain a long-term individual based study. As a
consequence, many field studies end before time, without reaching the number of
years or the amount of data needed to meet current scientific challenges and to
demonstrate their educational value.Here, we argue
that the value of LTIBS is multidimensional and it grows steadily with time. How and when does a long-term field study become
important? [..] continue reading here
