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Papers by Griselda Escalona

mastozoologiamexicana.org

The Campeche state harbors 55 species of bats and it has sites with high multispecific abundance ... more The Campeche state harbors 55 species of bats and it has sites with high multispecific abundance such as the cave called “El Volcán de los Murciélagos” in natural protected areas known as “Zona Sujeta a Conservación Ecológica Balam-Kú” in Calakmul ...

Revista Mexicana de …, 2002

We collected eight new records of mammal species from Campeche, México, including seven bats (Ord... more We collected eight new records of mammal species from Campeche, México, including seven bats (Order Chiroptera) and one carnivore (Order Carnivora). We also confirmed the presence in the state of Artibeus watsoni, Cynomops mexicanus (Chiroptera) and Lontra longicaudis (Carnivora). Hence, for Campeche bat species richness increased from 48 to 55 and carnivores 16 to 17.

Topographic and climatic variables affect demographic rates and habitat selection of many species... more Topographic and climatic variables affect demographic rates and habitat selection of many species, so these variables are useful for generating potential distribution models. In this research, the most important topographic and climatic variables were identified for the generation of Yucatan
parrot (Amazona xantholora) and Yellow-headed Parrot (Amazona oratrix) potential geographical distribution
model in the Yucatan Peninsula. Models were generated using MaxEnt (algorithm based on
Maximum Entropy). The presence records used were obtained from different available data bases from
The National Commission of Natural Protected Areas (CONANP) and El Colegio de la Frontera Sur.
One hundred replicas of models per species were developed and the best model selected is representing
the median value. Different thresholds were applied to the best model in order to obtain a presence/
absence map. Presence and absence records taken from field work were used to validate the model. To
know which of the variables contributed the most in the models generation, the ones with greater contribution
in the variables Jackknife with the AUC data and because of the contribution percentage of each
one, were selected. Amazona oratrix is potentially distributed in the southwestern portion of the Yucatan
Peninsula. Amazona xantholora is present around much of the Peninsula, including the Cozumel Island,
but it is absent within the areas where A. oratrix is located. The variable with greater contribution to A.
oratrix model was the average temperature of the driest quarter, while for A. xantholora were the digital
elevation model and the precipitation of the wettest and coldest quarters. For none of the two species it is
observed a direct relationship between vegetation gradient established within the northern and southern
of the Peninsula, and the potential geographical distribution area. The particular knowledge about the
environmental factors that influence the potential geographical distribution of these species can be useful for conservation actions and for future evaluation of the changes that such distribution might suffer.

Information on species’ abundances of members of the Family Psittacidae (parrots) is scarce. We d... more Information on species’ abundances
of members of the Family Psittacidae (parrots) is scarce.
We determined relative abundances of parrots in nine
areas of the Yucatan Peninsula; six sampled during the
years 2011–2012, and three during 2008–2010. We
counted parrots on 360 plots, calculated relative
abundance, and constructed dominance - diversity
graphs. Six species were identified in the study areas:
Amazona albifrons, Eupsittula nana, Amazona xantholora,
Amazona autumnalis, Amazona oratrix and Pionus
senilis. The southern Yucatan Peninsula harbored the
highest number of species. Overall, E. nana was the
most abundant species, although in the southern portion
of the peninsula A. albifrons was dominant. Using the
abundance values obtained in this research, we can
begin to identify and establish new priority sites for
parrot conservation within the Yucatan Peninsula and
develop new proposals for conservation and sustainable
management practices in the region.

The loss, degradation, and fragmentation of forested areas are endangering parrot populations. In... more The loss, degradation, and fragmentation of forested areas are endangering parrot populations. In
this study, we determined the influence of fragmentation in relation to vegetation cover, land use, and spatial
configuration of fragments on the potential geographical distribution patterns of parrots in the Yucatan Penin􀀐
sula, Mexico. We used the potential geographical distribution for eight parrot species, considering the recently
published maps obtained with the maximum entropy algorithm, and we incorporated the probability distribution
for each species. We calculated 71 metrics/variables that evaluate forest fragmentation, spatial configuration of
fragments, the ratio occupied by vegetation, and the land use in 100 plots of approximately 29 km², randomly
distributed within the presence and absence areas predicted for each species. We also considered the rela􀀐
tionship between environmental variables and the distribution probability of species. We used a partial least
squares regression to explore patterns between the variables used and the potential distribution models. None
of the environmental variables analyzed alone determined the presence/absence or the probability distribution
of parrots in the Peninsula. We found that for the eight species, either due to the presence/absence or the
probability distribution, the most important explanatory variables were the interaction among three variables,
particularly the interactions among the total forest area, the total edge, and the tropical semi–evergreen me􀀐
dium–height forest. Habitat fragmentation influenced the potential geographical distribution of these species in
terms of the characteristics of other environmental factors that are expressed together with the geographical
division, such as the diff erent vegetation cover ratio and land uses in deforested areas.

mastozoologiamexicana.org

The Campeche state harbors 55 species of bats and it has sites with high multispecific abundance ... more The Campeche state harbors 55 species of bats and it has sites with high multispecific abundance such as the cave called “El Volcán de los Murciélagos” in natural protected areas known as “Zona Sujeta a Conservación Ecológica Balam-Kú” in Calakmul ...

Revista Mexicana de …, 2002

We collected eight new records of mammal species from Campeche, México, including seven bats (Ord... more We collected eight new records of mammal species from Campeche, México, including seven bats (Order Chiroptera) and one carnivore (Order Carnivora). We also confirmed the presence in the state of Artibeus watsoni, Cynomops mexicanus (Chiroptera) and Lontra longicaudis (Carnivora). Hence, for Campeche bat species richness increased from 48 to 55 and carnivores 16 to 17.

Topographic and climatic variables affect demographic rates and habitat selection of many species... more Topographic and climatic variables affect demographic rates and habitat selection of many species, so these variables are useful for generating potential distribution models. In this research, the most important topographic and climatic variables were identified for the generation of Yucatan
parrot (Amazona xantholora) and Yellow-headed Parrot (Amazona oratrix) potential geographical distribution
model in the Yucatan Peninsula. Models were generated using MaxEnt (algorithm based on
Maximum Entropy). The presence records used were obtained from different available data bases from
The National Commission of Natural Protected Areas (CONANP) and El Colegio de la Frontera Sur.
One hundred replicas of models per species were developed and the best model selected is representing
the median value. Different thresholds were applied to the best model in order to obtain a presence/
absence map. Presence and absence records taken from field work were used to validate the model. To
know which of the variables contributed the most in the models generation, the ones with greater contribution
in the variables Jackknife with the AUC data and because of the contribution percentage of each
one, were selected. Amazona oratrix is potentially distributed in the southwestern portion of the Yucatan
Peninsula. Amazona xantholora is present around much of the Peninsula, including the Cozumel Island,
but it is absent within the areas where A. oratrix is located. The variable with greater contribution to A.
oratrix model was the average temperature of the driest quarter, while for A. xantholora were the digital
elevation model and the precipitation of the wettest and coldest quarters. For none of the two species it is
observed a direct relationship between vegetation gradient established within the northern and southern
of the Peninsula, and the potential geographical distribution area. The particular knowledge about the
environmental factors that influence the potential geographical distribution of these species can be useful for conservation actions and for future evaluation of the changes that such distribution might suffer.

Information on species’ abundances of members of the Family Psittacidae (parrots) is scarce. We d... more Information on species’ abundances
of members of the Family Psittacidae (parrots) is scarce.
We determined relative abundances of parrots in nine
areas of the Yucatan Peninsula; six sampled during the
years 2011–2012, and three during 2008–2010. We
counted parrots on 360 plots, calculated relative
abundance, and constructed dominance - diversity
graphs. Six species were identified in the study areas:
Amazona albifrons, Eupsittula nana, Amazona xantholora,
Amazona autumnalis, Amazona oratrix and Pionus
senilis. The southern Yucatan Peninsula harbored the
highest number of species. Overall, E. nana was the
most abundant species, although in the southern portion
of the peninsula A. albifrons was dominant. Using the
abundance values obtained in this research, we can
begin to identify and establish new priority sites for
parrot conservation within the Yucatan Peninsula and
develop new proposals for conservation and sustainable
management practices in the region.

The loss, degradation, and fragmentation of forested areas are endangering parrot populations. In... more The loss, degradation, and fragmentation of forested areas are endangering parrot populations. In
this study, we determined the influence of fragmentation in relation to vegetation cover, land use, and spatial
configuration of fragments on the potential geographical distribution patterns of parrots in the Yucatan Penin􀀐
sula, Mexico. We used the potential geographical distribution for eight parrot species, considering the recently
published maps obtained with the maximum entropy algorithm, and we incorporated the probability distribution
for each species. We calculated 71 metrics/variables that evaluate forest fragmentation, spatial configuration of
fragments, the ratio occupied by vegetation, and the land use in 100 plots of approximately 29 km², randomly
distributed within the presence and absence areas predicted for each species. We also considered the rela􀀐
tionship between environmental variables and the distribution probability of species. We used a partial least
squares regression to explore patterns between the variables used and the potential distribution models. None
of the environmental variables analyzed alone determined the presence/absence or the probability distribution
of parrots in the Peninsula. We found that for the eight species, either due to the presence/absence or the
probability distribution, the most important explanatory variables were the interaction among three variables,
particularly the interactions among the total forest area, the total edge, and the tropical semi–evergreen me􀀐
dium–height forest. Habitat fragmentation influenced the potential geographical distribution of these species in
terms of the characteristics of other environmental factors that are expressed together with the geographical
division, such as the diff erent vegetation cover ratio and land uses in deforested areas.