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2 resultados encontrados para: AUTOR: Chapa Vargas, Leonardo
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1.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Landscape composition influences abundance patterns and habitat use of three ungulate species in fragmented secondary deciduous tropical forests, Mexico
García Marmolejo, Gabriela (autora) ; Chapa Vargas, Leonardo (autor) ; Weber, Manuel (autor) ; Huber Sannwald, Elisabeth (autora) ;
Contenido en: Global Ecology and Conservation Vol. 3 (January 2015), p. 744–755 ISSN: 2351-9894
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Secondary forests are extensive in the tropics. Currently, these plant communities are the available habitats for wildlife and in the future they will possibly be some of the most wide-spread ecosystems world-wide. To understand the potential role of secondary forests for wildlife conservation, three ungulate species were studied: Mazama temama, Odocoileus virginianus and Pecari tajacu. We analyzed their relative abundance and habitat use at two spatial scales: (1) Local, where three different successional stages of tropical deciduous forest were compared, and (2) Landscape, where available habitats were compared in terms of landscape composition (proportion of forests, pastures and croplands within 113 ha). To determine the most important habitat-related environmental factors influencing the Sign Encounter Rate (SER) of the three ungulate species, 11 physical, anthropogenic and vegetation variables were simultaneously analyzed through model selection using Akaike’s Information Criterion. We found, that P. tajacu and O. virginianus mainly used early successional stages, while M. temama used all successional stages in similar proportions. The latter species, however, used early vegetation stages only when they were located in landscapes mainly covered by forest (97%). P. tajacu and O. virginianus also selected landscapes covered essentially by forests, although they required smaller percentages of forest (86%). All ungulate species avoided landscape fragments covered by pastures. For all three species, landscape composition and human activities were the variables that best explained SER. We concluded that landscape is the fundamental scale for ungulate management, and that secondary forests are potentially important landscape elements for ungulate conservation.


2.
- Artículo con arbitraje
Nest survival in the neotropical black catbird (Melanoptila glabrirostris)
Roldán Clarà, Blanca ; LaPergola, Joshua B. (coaut.) ; Chapa Vargas, Leonardo (coaut.) ; Calmé, Sophie (coaut.) ;
Contenido en: Journal of Ornithology Vol. 154, no. 2 (April 2013), p. 491-499 ISSN: 0006-3630
Resumen en: Inglés | Alemán |
Resumen en inglés

We estimated nest survival and evaluated factors affecting this demographic parameter for the Black Catbird (Melanoptila glabrirostris), a poorly known mimid endemic to the Yucatán Peninsula. During the 2008 and 2009 breeding seasons, we monitored 136 nests spread across four sites in Mexico, including three mainland coastal sites in the Sian Ka’an Biosphere Reserve and one site on Cozumel Island. We documented higher nest loss in the mainland sites (74 % failed) in contrast to the island site (21 % failed). Based on our observations, we suspect that predation was the main cause of nest failure. Using logistic exposure models and Akaike’s Information Criterion, we found date, nest age, and nest type to be the main factors influencing nest survival. Nest survival was lower for open cup-nests in comparison with semi-cavity nests. Interval nest survival (proportion of nests expected to survive the entire nesting season) was 0.102 (CI = 0–0.660) for open-cup nests and 0.618 (CI = 0–0.981) for semi-cavity nests. Additional research on adult and juvenile survival and dispersal patterns, especially for the mainland population, is needed to determine if these rates of nest survival are sufficient to maintain stable populations.

Resumen en alemán

Wir bestimmten Überlebensraten von Nestern des Glanzkatzenvogels (Melanoptila glabrirostris), einem wenig bekannten, auf der Yucatán-Halbinsel endemischen Vertreter der Mimidae, und bewerteten Faktoren, die diesen demographischen Parameter beeinflussen. Während der Brutsaisons 2008 und 2009 beobachteten wir 136 Nester, die sich auf vier verschiedene Gebiete in Mexiko verteilten, darunter drei küstennahe Gebiete auf dem Festland im Sian Ka’an Biosphärenreservat und eines auf der Insel Cozumel. Wir dokumentierten höhere Nestverluste in den Festlandsgebieten (74 % Verlust), im Gegensatz zum Untersuchungsgebiet auf der Insel (21 % Verlust). Auf der Grundlage unserer Beobachtungen nehmen wir an, dass Prädation die Hauptursache für den Nestverlust war. Die Verwendung logistischer Expositionsmodelle und Akaikes Informationskriterium ergab, dass Datum, Nestalter und Nesttypus die Hauptfaktoren darstellten, die den Nestverlust beeinflussten. Überlebensraten von offenen Napfnestern waren niedriger als die von Halbhöhlennestern. Intervall-Nestüberlebensraten (Anteil an Nestern, die erwartungsgemäß die gesamte Brutsaison überleben) lagen bei 0.102 (CI = 0–0.660) für offene Napfnester und bei 0.618 (CI = 0–0.981) für Halbhöhlennester. Weitere Untersuchungen zu Überlebensraten und Dispersionsmustern von Jung- und Altvögeln sind notwendig um festzustellen, ob speziell die Nestüberlebensraten auf dem Festland ausreichen, die Populationen stabil zu halten.