Vol. 32 – 2006 - Ecologia Mediterranea

ence of historical biogeographic patterns associated with
Quaternary climatic changes, and the current ecological
patterns associated with diverse disturbances (fragmentation,
fire, grazing) or environmental changes, is examined.
Three species with a distribution more or less narrow are
studied: two snowflakes, Acis nicaeensis (Alliaceae)
endemic from the Southern Maritime Alps and Acis fabrei,
endemic from the Mont Ventoux, and Gentiana ligustica
(Gentianaceae) endemic from the South-Western Alps in
France and Italy.
Phylogeographic data of G. ligustica combined with glacial
history suggest the presence of several peripheral
microrefugia in the south and in valley lowlands of the
Maritime and Ligurian Alps, and the existence of several
postglacial migration routes. At present, endemic plants
along the littoral, among which A. nicaeensis, are seriously
endangered by diverse and serious human impacts. Recent
habitat fragmentation decreases population viability, reducing
population size which induces an extinction vortex. In
addition, rapid colonisation by ligneous species, due to
land-abandonment, induces negative effects on the population
structure and dynamic of A. nicaeensis. On the other
hand, disturbances characterized by intermediate intensity
and frequency, among which cattle grazing for G. ligustica
and fire for A. nicaeensis, favour population persistence.
Despite the higher rarity of A. fabrei, the three known populations
seem not threatened at short-term, in contrast with
A. nicaeensis which needs an urgent planning of habitat
conservation. Also, the natural habitat fragmentation of
G. ligustica, due to paleoecological events, has possibly
induced limited consequences on its genetic diversity.
Within a global change context, it appears necessary to propose
some specific conservation strategies, including the
preservation of intermediate disturbances, habitat conservation,
or an assessment of population history and of their
ecogeographical variability.
Karen BOURGEOIS
2006
Ecology, biology and conservation
of a Mediterranean endemic seabird
Puffinus yelkouan
Thèse de doctorat en sciences soutenue le 6 décembre 2006
à l’université Paul Cézanne, Aix-Marseille 3, Institut
méditerranéen d’écologie et de paléoécologie (IMEP, UMR-
CNRS 6116, équipe écologie du paysage et biologie de la
conservation, Europôle méditerranéen de l'Arbois, avenue
Philibert, BP 80, 13545 Aix-en-Provence cedex 04, France).
Jury – Éric VIDAL (MCF, université Paul Cézanne), P r Thierry TATONI
(université Paul Cézanne), directeur et codirecteur de thèse. Jacob
ecologia mediterranea – Vol. 32 – 2006
Résumés de thèses
GONZALEZ-SOLIS (chargé de recherche, université de Barcelone,
Espagne) et Michel GAUTHIER-CLERC (chargé de recherche HDR, station
biologique de la Tour du Valat), rapporteurs. Bernard DECEUN-
INCK (chargé de mission, BirdLife International/LPO) et Matthieu
LECORRE (MCF, université de la Réunion), examinateurs.
Keywords: breeding biology, breeding habitat selection,
conservation biology, conservation status, introduced
predators, Mediterranean islands, seabird, yelkouan
shearwater.
Procellarids, particularly species of the Manx shearwater
taxonomic complex, are seabirds exhibiting a strong
vulnerability to their habitat disturbance because of their
extreme K demographic strategy. In this complex, the yelkouan
shearwater, Puffinus yelkouan, is a unique case with
its strict endemism to the closed Mediterranean Basin, its
recent elevation to the specific rank and the magnitude of
lacking knowledge of this species. Thus, this thesis general
purpose was to study this still poorly known pelagic
seabird, in order to at least partially fill the knowledge gaps
for this species ecology and biology, and in order to provide
tangible data for management and conservation action
planning for this species.
We firstly reviewed this species population, distribution and
threats throughout its world range. This emphasized the
dramatic lack of reliable and available data concerning the
yelkouan shearwater, yielding to imprecise and overestimated
breeding numbers, to a lack of confirmation for purported
breeding sites, and to the consideration of a stable
population while consistent data suggested population
decline and strong threats. Due to the poorness of existing
data on this species, we secondly developed basic methodologies
to ease its study. Thus, a new sexing method, based
on vocalization analysis, was shown perfectly efficient and
non-invasive in comparison with the classical morphometric
sexing. Moreover, shearwater presence and activity patterns
at colonies were analysed and we demonstrated that
ambient light, breeding cycle and wind speed should be
essential in monitoring and census planning. Both nest-cavity
and colony-site selection analyses, thirdly, allowed to
describe the species ecological preferences, and, above all,
to highlight a particularly low suitable breeding habitat proportion
that is currently occupied by yelkouan shearwaters.
Finally, patterns and impact of feral cat predation were
studied through cat scat analysis and by demographic modelling
(Population Viability Analysis). This predation constitutes
a strong threat for the yelkouan shearwater on our
study site and this analysis revealed an unexpected shearwater
population structure.
These results prioritized cat eradication on the study site
in order to enhance shearwater population dynamics and
to avoid its extinction. Moreover, the abundance of available
and favourable breeding habitat will certainly support
an increase in the shearwater population. By continuing
current monitoring and actions, and by increasing study
area, we will be able to precise the understanding of terrestrial
yelkouan shearwater breeding cycle and to validate
our hypothesis concerning the species population structure.
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