The Influence of Large Tree Density on Howler Monkey (Alouatta palliata mexicana) Presence in Very Small Rain Forest Fragments

Abstract

The populations of the Mexican mantled howler monkey (Alouatta palliata mexicana) in the Los Tuxtlas region, Mexico, have declined drastically due to habitat loss and fragmentation. Nevertheless, several troops still inhabit very small and isolated rain forest fragments. We identified the main vegetation attributes that can favor the presence of howlers within 18 small (< 10-ha) fragments that did not differ significantly in size, shape, and isolation (nine occupied and nine unoccupied by howlers). We found that habitat quality (i.e., food resources and vegetation structure) affected howler incidence in small fragments. Particularly, the occupied fragments showed greater density of big trees (dbh > 60 cm), greater total basal area, greater basal area of persistent tree species, and greater basal area of top food species than the unoccupied fragments; suggesting that even for small fragments the loss of big trees and particularly the decrease in size class of the top food species can negatively affect howler distribution in highly fragmented landscapes. These findings could be used to establish foreground conservation areas for this critically endangered subspecies in fragmented landscapes of Los Tuxtlas.Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp.

Effects of climate and forest structure on palms, bromeliads and bamboos in Atlantic Forest fragments of Northeastern Brazil

“…However, in accordance to our results, other studies found smaller abundance of some palm species in more degraded forests (Arroyo-Rodríguez et al, 2007a;Baez and Balslev, 2007). Forest structure may also influence the occurrence and abundance of seed dispersers (Balcomb et al, 2000;Arroyo-Rodríguez et al, 2007b). Taller forests, with larger trees and closed canopy resemble forests in a later stage of succession, which could retain a larger fraction of the original frugivore guild.…”

Population Viability Analysis of Howler Monkeys (Alouatta Palliata Mexicana) in a Highly Fragmented Landscape in Los Tuxtlas, Mexico

“…Only 5% consists of continuous rainforest at high elevations (>800 m) [25]. As a result, the remaining population is spread across archipelagoes of forest fragments that vary in size, isolation distance, age, and quality, resulting in precarious demographic and ecological conditions [26][27][28][29]. Studies at Los Tuxtlas have shown that the presence and abundance of howlers monkeys are positively related to fragment size and quality, and negatively related to fragment isolation [18,19,25,29,30].…”

Use of Wild Foods During the Rainy Season by a Reintroduced Population of Scarlet Macaws (Ara Macao Cyanoptera) in Palenque, Mexico

“…The IVI is an indicator of the species importance in the tree community and is calculated by the sum of the species density (number of individuals of species x / area sampled), frequency (number of transects in which species x occurs / total number of transects) and dominance (total basal area of the species in the sampled area). The higher the value of the IVI, the higher the importance of species in the tree community [33].…”