Double jeopardy for ecologically rare birds and terrestrial mammals


Date:
October 8, 2020
Source:
CNRS
Summary:
Common assumptions notwithstanding, rare species can play unique
and essential ecological roles. After studying two, scientists have
demonstrated that, though these species are found on all continents,
they are more threatened by human pressures than ecologically
common species and will also be more impacted by future climate
change. Thus they are in double jeopardy. The researchers' findings
show that conservation programmes must account for the ecological
rarity of species.



FULL STORY ========================================================================== Common assumptions notwithstanding, rare species can play unique and
essential ecological roles. After studying two databases that together
cover all known terrestrial mammals and birds worldwide, scientists from
the CNRS, the Foundation for Biodiversity Research (FRB), Universite'
Grenoble Alpes, and the University of Montpellier[1] have demonstrated
that, though these species are found on all continents, they are more threatened by human pressures than ecologically common species and will
also be more impacted by future climate change. Thus they are in double jeopardy. The researchers' findings, published in Nature Communications (October 8, 2020), show that conservation programmes must account for
the ecological rarity of species.


==========================================================================
It has long been thought that rare species contribute little to the
functioning of ecosystems. Yet recent studies have discredited that
idea: rarity is a matter not only of the abundance or geographical
range of a species, but also of the distinctiveness of its ecological functions. Because these functionally distinct species are irreplaceable,
it is essential we understand their ecological characteristics, map
their distributions, and evaluate how vulnerable they are to current
and future threats.

Using two databases that collect information on the world's terrestrial
mammals (4,654 species) and birds (9,287 species), scientists from the
FRB's Centre de Synthe`se et d'Analyse de la Biodiversite' (CESAB),
CNRS research laboratories, Universite' Grenoble Alpes, the University
of Montpellier, and partner institutes divided the earth's surface
into 50 x 50 km squares and determined the number of ecologically rare
species within each. They showed that ecological rarity among mammals
is concentrated in the tropics and the southern hemisphere, with peaks
on Indonesian islands, in Madagascar, and in Costa Rica.

Species concerned are mostly nocturnal frugivores, like bats and lemurs,
and insectivores, such as small rodents. Ecologically rare bird species
are mainly found in tropical and subtropical mountainous regions,
especially in New Guinea, Indonesia, the Andes, and Central America. The
birds in question are essentially frugivorous or nectarivorous,
hummingbirds being an example. For birds and terrestrial mammals alike,
islands are hotspots of ecological rarity.

The researchers also ranked these species according to their IUCN Red
List status[2] and found they made up the bulk of the threatened species categories.

That is, ecologically rare mammals account for 71% of Red List threatened species (versus 2% for ecologically common mammals); and ecologically
rare birds, 44.2% (versus 0.5% for ecologically common birds). For
each species, they determined (i) anthropogenic pressure exerted; (ii)
human development indexes (HDIs) of host countries; and (iii) exposure
to armed conflicts. The last two of these elements shape conservation
policies. The scientists observed that human activity had a greater impact
on ecologically rare mammals and birds than on more common species, and
that these rare species were found in countries of every kind of profile, irrespective of HDI or the prevalence of warfare.[3] They used models to demonstrate that ecologically rare species will be the greatest victims
of climate change, many of them facing extinction within 40 years.

This profiling of ecologically rare species makes it clear that current conservation efforts, even in zones already protected, are insufficient.

Conservation strategies still too often ignore functional distinctiveness
and focus instead on population sizes. But it is essential to take
this distinctiveness into account, letting this knowledge guide steps
taken to protect these rare species. As they are necessary for healthy ecosystems, a true paradigm shift in conservation policy is needed to
ensure their survival.

Notes 1These scientists are affiliated with the following research units:
the Centre for Marine Biodiversity, Exploitation and Conservation (CNRS
/ University of Montpellier / IRD / IFREMER), the Centre d'E'cologie Fonctionnelle et E'volutive (CNRS / University of Montpellier / Paul
Vale'ry University / EPHE / IRD), the Laboratoire d'E'cologie Alpine
(CNRS / Universite' Grenoble Alpes / Universite' Savoie Mont Blanc),
and the Centre de Synthe`se et d'Analyse sur la Biodiversite' (CESAB)
at the FRB. This research is the product of FREE, a CESAB team dedicated
to the coherent integration of biodiversity data. FREE is jointly funded
by the FRB and EDF.

2The International Union for Conservation of Nature (IUCN) is a leading international NGO focused on nature conservation. It evaluates the risk
of extinction faced by different species, assigning each to a particular category (e.g., 'Least Concern', 'Near Threatened', 'Vulnerable',
'Endangered', or 'Extinct').

3For example, the Philippines, where HDI is low and armed conflicts
prevalent, are a hive for ecologically rare species (19 terrestrial
mammals and 15 birds).

Yet Australia, where HDI is high and armed conflict rare, is also home
to many ecologically rare species (10 terrestrial mammals and 10 birds).


========================================================================== Story Source: Materials provided by CNRS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Nicolas Loiseau, Nicolas Mouquet, Nicolas Casajus, Matthias
Grenie', Maya
Gue'guen, Brian Maitner, David Mouillot, Annette Ostling, Julien
Renaud, Caroline Tucker, Laure Velez, Wilfried Thuiller, Cyrille
Violle. Global distribution and conservation status of ecologically
rare mammal and bird species. Nature Communications, 2020; 11 (1)
DOI: 10.1038/s41467-020- 18779-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201008083758.htm

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