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Changes in Habitat Structure May Explain Decrease in Reintroduced Mohor Gazelle Population in the Guembeul Fauna Reserve, Senegal.

Moreno E, Sane A, Benzal J, Ibáñez B, Sanz-Zuasti J, Espeso G - Animals (Basel) (2012)

Bottom Line: In spite of recent reviews, it is difficult to reach general conclusions about its value as a conservation tool, as authors are reluctant to publish unsuccessful results.The population grew progressively, albeit slowly, during the first 20 years after release, but then declined dramatically, until the population in 2009 was estimated at no more than 13-15 individuals.Our results show that the Mohor gazelle in Guembeul is found in open habitats with less developed canopy where the grass is shorter, suggesting the possibility that changes in habitat structure have taken place during the time the gazelles have been in the Reserve, reducing the amount of suitable habitat.

View Article: PubMed Central - PubMed

Affiliation: Department of Functional and Evolutionary Ecology, Estación Experimental de Zonas Áridas, CSIC, Carretera de Sacramento s/n, La Cañada de San Urbano, E-04120 Almería, Spain. emoreno@eeza.csic.es.

ABSTRACT
Reintroduction is a widespread method for saving populations of endangered species from extinction. In spite of recent reviews, it is difficult to reach general conclusions about its value as a conservation tool, as authors are reluctant to publish unsuccessful results. The Mohor gazelle is a North African gazelle, extinct in the wild. Eight individuals were reintroduced in Senegal in 1984. The population grew progressively, albeit slowly, during the first 20 years after release, but then declined dramatically, until the population in 2009 was estimated at no more than 13-15 individuals. This study attempts to determine the likelihood of gazelle-habitat relationships to explain why the size of the gazelle population has diminished. Our results show that the Mohor gazelle in Guembeul is found in open habitats with less developed canopy where the grass is shorter, suggesting the possibility that changes in habitat structure have taken place during the time the gazelles have been in the Reserve, reducing the amount of suitable habitat. Reintroduction design usually concentrates on short-term factors that may affect survival of the released animals and their descendants (short-term achievement), while the key factors for assessing its success may be those that affect the long-term evolution of the population.

No MeSH data available.


Related in: MedlinePlus

Photos showing changes occurred in vegetation cover in RF Guembeul: left side pictures taken in 13 March 2003; right side pictures taken in 5 April 2011. General view is shown above; details of plots in red, below. Photos have been taken from Google©; accessed on 28 May 2012.
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animals-02-00347-f002: Photos showing changes occurred in vegetation cover in RF Guembeul: left side pictures taken in 13 March 2003; right side pictures taken in 5 April 2011. General view is shown above; details of plots in red, below. Photos have been taken from Google©; accessed on 28 May 2012.

Mentions: A few months after creation, RF Guembeul was completely fenced off to protect the area from livestock grazing. At that time, it was a rather impoverished sandy habitat due mainly to overgrazing. However, fencing promoted recovery of vegetation, and four years later important changes in its landscape were reported [14]: In 1984 “Acacia spp shoots about 25–30 cm high were scattered around the Reserve, with very few mature trees”. In 1988 “the acacias and other trees had grown to a height of 3–5 m and were distributed fairly evenly some 6–10 m apart” and “a small area to the south-west is thickly covered by Opuntia tuna”. This has also changed with time, and this cactus is much more widely extended, especially in the West where it appeared in all plots sampled (Table 3). Unfortunately there is no quantified data available on habitat structure in the RF Guembeul in the past that would provide an accurate image of the hypothesized habitat changes over the past years, and which presumably could explain Mohor gazelle decline parallel to an increase in vegetation cover. However, by using historical as well as current Google© images of the Reserve (Figure 2), we can observe changes in the extent of the canopy roughly by comparing pictures taken in 2003 and pictures taken in 2011, and this change is much more pronounced in West Guembeul, very likely associated with the expansion of Opuntia in this part of the Reserve. Remote sensing techniques could probably be used in a future follow up study to underpin our current results.


Changes in Habitat Structure May Explain Decrease in Reintroduced Mohor Gazelle Population in the Guembeul Fauna Reserve, Senegal.

Moreno E, Sane A, Benzal J, Ibáñez B, Sanz-Zuasti J, Espeso G - Animals (Basel) (2012)

Photos showing changes occurred in vegetation cover in RF Guembeul: left side pictures taken in 13 March 2003; right side pictures taken in 5 April 2011. General view is shown above; details of plots in red, below. Photos have been taken from Google©; accessed on 28 May 2012.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494292&req=5

animals-02-00347-f002: Photos showing changes occurred in vegetation cover in RF Guembeul: left side pictures taken in 13 March 2003; right side pictures taken in 5 April 2011. General view is shown above; details of plots in red, below. Photos have been taken from Google©; accessed on 28 May 2012.
Mentions: A few months after creation, RF Guembeul was completely fenced off to protect the area from livestock grazing. At that time, it was a rather impoverished sandy habitat due mainly to overgrazing. However, fencing promoted recovery of vegetation, and four years later important changes in its landscape were reported [14]: In 1984 “Acacia spp shoots about 25–30 cm high were scattered around the Reserve, with very few mature trees”. In 1988 “the acacias and other trees had grown to a height of 3–5 m and were distributed fairly evenly some 6–10 m apart” and “a small area to the south-west is thickly covered by Opuntia tuna”. This has also changed with time, and this cactus is much more widely extended, especially in the West where it appeared in all plots sampled (Table 3). Unfortunately there is no quantified data available on habitat structure in the RF Guembeul in the past that would provide an accurate image of the hypothesized habitat changes over the past years, and which presumably could explain Mohor gazelle decline parallel to an increase in vegetation cover. However, by using historical as well as current Google© images of the Reserve (Figure 2), we can observe changes in the extent of the canopy roughly by comparing pictures taken in 2003 and pictures taken in 2011, and this change is much more pronounced in West Guembeul, very likely associated with the expansion of Opuntia in this part of the Reserve. Remote sensing techniques could probably be used in a future follow up study to underpin our current results.

Bottom Line: In spite of recent reviews, it is difficult to reach general conclusions about its value as a conservation tool, as authors are reluctant to publish unsuccessful results.The population grew progressively, albeit slowly, during the first 20 years after release, but then declined dramatically, until the population in 2009 was estimated at no more than 13-15 individuals.Our results show that the Mohor gazelle in Guembeul is found in open habitats with less developed canopy where the grass is shorter, suggesting the possibility that changes in habitat structure have taken place during the time the gazelles have been in the Reserve, reducing the amount of suitable habitat.

View Article: PubMed Central - PubMed

Affiliation: Department of Functional and Evolutionary Ecology, Estación Experimental de Zonas Áridas, CSIC, Carretera de Sacramento s/n, La Cañada de San Urbano, E-04120 Almería, Spain. emoreno@eeza.csic.es.

ABSTRACT
Reintroduction is a widespread method for saving populations of endangered species from extinction. In spite of recent reviews, it is difficult to reach general conclusions about its value as a conservation tool, as authors are reluctant to publish unsuccessful results. The Mohor gazelle is a North African gazelle, extinct in the wild. Eight individuals were reintroduced in Senegal in 1984. The population grew progressively, albeit slowly, during the first 20 years after release, but then declined dramatically, until the population in 2009 was estimated at no more than 13-15 individuals. This study attempts to determine the likelihood of gazelle-habitat relationships to explain why the size of the gazelle population has diminished. Our results show that the Mohor gazelle in Guembeul is found in open habitats with less developed canopy where the grass is shorter, suggesting the possibility that changes in habitat structure have taken place during the time the gazelles have been in the Reserve, reducing the amount of suitable habitat. Reintroduction design usually concentrates on short-term factors that may affect survival of the released animals and their descendants (short-term achievement), while the key factors for assessing its success may be those that affect the long-term evolution of the population.

No MeSH data available.


Related in: MedlinePlus