Rosamond Coates-Estrada

Tropical rain forest fragmentation and wild populations of primates at Los Tuxtlas, Mexico

In view of the extensive destruction, fragmentation, and conversion of primate habitats to anthropogenic vegetation, information on Neotropical primate ability to use a landscape consisting of forest fragments and agricultural habitats is necessary to understand the ecological flexibility of the species involved and it is of relevance to the design of conservation scenarios at the landscape level. We censused howlers and spider monkeys in 126 forest fragments and in 44 agricultural sites at Los Tuxtlas, southern Veracruz, Mexico, and used the IDRISI Geographic Information System to assess the extent of primate habitat remaining. We conducted economic surveys to assess the productivity of several systems of land management, including cattle ranching. Seventy- five percent of native habitat has been lost at Los Tuxtlas, 20% remains in the form of isolated fragments of vegetation, and only 5% consists of contiguous rain forest at high elevations (> 800 m). Howlers and spider monkeys were present in only 60 and 8% of the forest sites investigated, respectively, attesting to extensive local extinction. Populations of both species are small and found in a fragmented and isolated condition throughout the landscape. A large number of howlers were detected in artifactual habitats such as cacao, coffee and mixed (cacao and coffee) plantations shaded by rain forest trees. Residual rain forest vegetation along streams, rivers, and lakes facilitated the interfragment and interhabitat movement of howlers. Economic surveys showed that some of the agricultural habitats were more productive than cattle ranching. Conservation of spider monkeys requires large areas of contiguous forest, but only small areas are present at high elevations. Howlers are restricted to elevations < 800 m, where most of the forest has disappeared, but can apparently exist in a matrix of forest fragments, arboreal agricultural habitats, and pasture lands. Structural aspects of the vegetation and connectivity among habitat islands may be indispensable components of both landscape scenarios.

Howler monkeys ( Alouatta palliata ), dung beetles (Scarabaeidae) and seed dispersal: ecological interactions in the tropical rain forest of Los Tuxtlas, Mexico

La dispersion de semillas por monos aulladorcs ( Alouatla palliata ) y el impacto de la aclividad de forrajeo y nidificacion de escarabajos coprofagos sobre cl destino de las semillas dispersadas fucron cstudiados en la selva de Los Tuxtlas, Mexico. La mayoria (≥90%) de las semillas (28 cspecies de plantas) dispersadas por los monos son deprcdadas por rocdores. El aprovechamicnto de matcria faecal por escarabajos en el suelo dc la selva resulta en la relocalizacion y cntcrramiento accidental de tin gran numero dc semillas poco despues de ser expulsadas por los monos a traves de sus heces. Los escarabajos enticrran las semillas a profundidades que van desde 2.5 a

Bats in continuous forest, forest fragments and in an agricultural mosaic habitat-island at Los Tuxtlas, Mexico

With the aim of determining what kind of landscape mosaics might sustain maximum diversity and minimum species loss, dung beetles were sampled with baited pitfall traps to compare species richness and species composition in a tract of continuous forest, forest fragments and a habitat island consisting of a mosaic of forest and arboreal crops in Los Tuxtlas, southern Mexico. We captured 7332 dung beetles representing 33 species. Similar numbers of species were captured in the three habitats. However, 56% of individuals were captured in the continuous forest, 29% in the mosaic habitat and 15% in the forest fragments. Eight species (Canthon femoralis, Copris laeviceps, Canthidium centrale, Onthophagus batesi, Deltochilum pseudoparile, O. rhinolophus, Canthon viridis vazquezae and Dich- otomius satanus) accounted for 90% of the captures, but their relative dominance varied among habitats. A clear trend was evident in the number of dung beetles captured in the dung processing guilds (rollers / tunnelers) as well as in the diurnal and nocturnal guilds, with captures decreasing from the continuous forest to the mosaic habitat to the forest fragments. A similar trend was detected in detection rates for medium and small size dung producing mammals. Species richness of forest fragments and mosaic habitat did not differ from that found in the continuous forest, but these habitats differ significantly in species richness from isolated shaded and unshaded plantations, linear strips of vegetation, the forest-pasture edge and pastures according to rarefaction analysis. The co-occurrence of the continuous forest, the mosaic habitat and the cluster of forest fragments in close proximity seems to be preserving a diverse assemblage of dung beetle species in the local landscape.

DUNG AND CARRION BEETLES IN TROPICAL RAIN FOREST FRAGMENTS AND AGRICULTURAL HABITATS AT LOS TUXTLAS, MEXICO

At Los Tuxtlas, Mexico, presence of dung and carrion beetles, were sampled using baited pitfall traps, at the following habitats: isolated forest fragments, forest edges, plantations (coffee, cacao, mixed, citrus and allspice), live fences and pastures. A total of 14,269 beetles representing 36 species were captured. Onthophagus batesi , Canthon femoralis , Canthidium centrale , Copris laeviceps , O. rhinolophus and Deltochilium pseudoparile accounted for 75% of the captures in the overall sample from 79 sites. Across forest fragments capture rates of species and individuals were associated positively to area and negatively to isolating distance. Rarefaction analysis showed that forest fragments were the most species-rich habitats followed by the mixed and cacao plantations, the forest edge, live fences and coffee, citrus and allspice plantations. Pastures were the least species-rich habitat. Horizontal and vertical diversity of the vegetation at the habitats studied influenced the species richness of dung and carrion beetles and the number of species in common between forest fragments and human-made habitats. A significant relationship existed between the number of non-flying mammals recorded at the study sites and the richness of species and individuals of dung beetles at the habitats investigated. The relevance of this information is discussed in the light of the ecological flexibility of dung and carrion beetle species and of possible conservation scenarios involving landscapes in which isolation of forest fragments is reduced by the presence in open areas of human-made vegetation such as plantations of cacao, coffee, cacao and coffee and live fences.

Feeding and general activity patterns of a howler monkey (Alouatta palliata) troop living in a forest fragment at Los Tuxtlas, Mexico

The feeding behavior and general activity patterns of a howler monkey troop living in a 3.6 ha forest fragment were studied at Los Tuxtlas, Mexico, for an annual cycle. Monthly samples of their feeding behavior indicated that they used 52 species of 24 plant families as sources of food. Of these, 67% were trees, which accounted for 96% of total feeding time recorded. Ten species of Moraceae, Cecropiaceae, Anacrdiaceae. and Sapotaceae contributed to 70% of the trees used and to almost 90% of feeding time. The number of plant species used per monthly record varied from 7 to 31 with an average of 19.9 species. Young leaves and ripe fruit were the principal items in the monthly diet of howlers and average percent of time spent consuming these plant parts was 46.7% and 34.8%, respectively. The use of tree species was found to be associated to their importance value and to their pattern of spatial dispersal in the study site. Availability of young leaves was fairly constant from month to month, but it presented a seasonal pattern, and there was a significantly lower number of tree species bearing ripe fruit through the year with brief pulses of production. The monthly activity pattern was found to be related to variations in the availability of young leaves and ripe fruit as well as to the values of the intermonthly overlap in plant species used. Resting and feeding presented a bimodal pattern of occurrence throughout the day that seemed to be related to variations in maximum ambient temperatures. Results are discussed in light of the small size and shape of the forest fragment inhabited by the howler troop. Am. J. Primatol. 48:167–183, 1999.

Tropical rain forest fragmentation, howler monkeys (Alouatta palliata), and dung beetles at Los Tuxtlas, Mexico

In Neotropical rain forests, fresh mammal dung, especially that of howler monkeys, constitutes an important resource used by dung beetles as food and for oviposition and further feeding by their larvae. Tropical rain forest destruction, fragmentation, and subsequent isolation causing reductions in numbers of and the disappearance of howler moneys may result in decreasing numbers of dung beetles, but this has not been documented. In this study, we present information on the presence of howlers and dung beetles in 38 isolated forest fragments and 15 agricultural habitats. Howler monkeys were censused by visual means, while dung beetles were sampled with traps baited with a mixture of howler, cow, horse, and dog dung. Results indicated that loss of area and isolation of forest fragments result in significant decrements in howlers and dung beetles. However, dung beetle abundance was found to be closely related to the presence of howler monkeys at the sites and habitats investigated. Scenarios of land management designed to reduce isolation among forest fragments may help sustain populations of howler monkeys and dung beetles, which may have positive consequences for rain forest regeneration. Am. J. Primatol. 48:253–262, 1999.

Dung beetles attracted to mammalian herbivore ( Alouatta palliata ) and omnivore ( Nasua narica ) dung in the tropical rain forest of Los Tuxtlas, Mexico

Dung beetles attracted to howler monkey ( Alouatta palliata ) and coati ( Nasua narica ) dung were studied for an annual cycle in the tropical rain forest of Los Tuxtlas, Mexico. Pitfall traps set for 24 h month −1 captured 1567 dung beetles of 21 species. The species Canlhidium martinto, Deltochilum pseudoparile and Canthon femoralis accounted for 62% of all individuals captured. While species overlap was high (> 80%) between diurnal and nocturnal samples and between howler monkey and coati dung baits, coati dung attracted species such as C. martinezi, D. pseudoparile and Onthophagus rhinolophus while species such as C. femoralis and Copris laeviceps were numerically dominant at howler monkey dung. Thirteen non-ball rolling dung beetle species and eight ball-rolling species accounted for 43% and for 57% of all beetles captured respectively. Dung beetles were present and active in all months of the year, but occurred in higher numbers between the months of March and October, when temperatures were higher. Relative abundance of howler monkey and coati dung in the rain forest of Los Tuxtlas was estimated at 11.2 g (fresh weight) ha −1 day −1 and at 13.0 g ha −1 day −1 respectively, a seemingly low amount for the large number of scarabs attracted to the dung.

Patterns of frugivore species richness and abundance in forest islands and in agricultural habitats at Los Tuxtlas, Mexico

Destruction and fragmentation of tropical rain forest result in a loss of species and of generating capacity of the ecosystem via animal vectors such as seed dispersal agents. To gather quantitative data regarding this ecological problem, birds and mammals were censused in 30 forest fragments, 15 agricultural islands representing five types of vegetation (coffee, cacao, citrus, pepper and mixed-crops) and in three pastures in Los Tuxtlas, southern Veracruz, Mexico. More than 6000 animals of 257 species were detected thus suggesting the existence of a rich species pool in the fragmented landscape. Frugivores accounted for 60% of species, for 72% of individuals censured and for 85% of the total animal biomass recorded. Clusters of small forest fragments ( 100 ha) forest islands. Pastures were especially poor in forest birds and mammals. While the agricultural islands studied contributed to only 1% of the total area of vegetation sampled, they contained 58% of all species detected and 34% of all individual birds and mammals censured. Recaptures indicated inter-island movements of forest birds and mammals. Forty percent of the species were detected in forest habitats only, the rest were detected in forest and in agricultural habitats. Seeds of forest interior plants dispersed by birds and bats were detected in the agricultural habitats. The value of agricultural islands as landscape features providing some degree of biotic connectivity among fragmented animal populations is discussed.

Bird species richness in vegetation fences and in strips of residual rain forest vegetation at Los Tuxtlas, Mexico

Fragmentation of the lowland tropical rain forest has resulted in loss of animal and plant species and isolation of remaining populations that puts them at risk. At Los Tuxtlas, Mexico, lowland rain forests are particularly diverse in the avian fauna they contain and while most of the forests have been fragmented by human activity, many of the fragments still harbor diverse assemblages of bird species. In these landscapes, linear strips of residual rain forest vegetation along streams as well as linear strips of vegetation fences (live fences) crossing the pastures might provide some connectivity to bird populations existed in forest fragments. We investigated bird species richness and relative abundance in one 6-km long section of live fences (LF) bordering a dirt road and in two 6-km long sections of residual forest vegetation along a river (MR) and one permanent stream (BS). We used point count procedures which resulted in the count of 2984 birds representing 133 species. At the LF site we detected 74% of the species, 72% at the BS site and 57% at the MR site. Only 38% of the species were common among sites. Neotropical migratory birds accounted for 34–41% of the species counted at all sites. While edge and open habitat birds accounted for 6–10% of the species and for 50% of the records at the three vegetation strips, about 90% of the species were forest birds. Distance to forest fragments and degree of disturbance of the vegetation seemed to negatively influence bird species presence at the BS and MR strips. Rarefaction analysis indicated that the LF strip was richer in species than the other two sites, but the occurrence of the three vegetation strips in the landscape seem to favor the presence of many more species. We discuss the value of these vegetation strips to birds as stepping stones in the fragmented landscape.

Species composition and reproductive phenology of bats in a tropical landscape at Los Tuxtlas, Mexico

The structure, composition and reproductive phenology of a bat assemblage were investigated in the tropical region of Los Tuxtlas, Mexico. A 90-km 2 landscape, originally occupied by rain forest, consisted of forest fragments and natural corridors of vegetation surrounded by pasturelands. Artificial strips of vegetation also were present as live fences. Bats were sampled with mist nets set at ground level in 52 forest fragments, three corridors, nine shaded plantations, six unshaded plantations and three live fences. We sampled each site twice, each time for a 5-h period for two consecutive nights. Bats were captured and released and the species identity and reproductive condition of adult females were recorded. Annual fruiting phenology and fruit production was measured with fruit traps in a forest site inthree 500 × 20-m transects. We captured 4799 bats of 39 species. At forest sites we recorded 97% of the species and captured 44% of the bats. In corridors we captured 76% of the species and 16% of the total individuals. In the plantations we captured 71% of the species and 32% of the individuals. In the live fences we captured 32% of the species and 8% of the individuals. Three species, Pteronotus parnelli, Carollia brevicauda and Glossophaga soricina, accounted for 52% of all bat captures. Fruit-eating species and fruit-eating insectivores accounted for 65% of captures. Fleshy fruits were available year-round, but a seasonal pattern was evident. Presence of lactating females seemed to be associated, in general, with rainfall and fruiting seasonality, but individual species displayed different patterns ranging from aseasonal polyoestry to seasonal bimodal polyoestry, sea- sonal polyoestry and seasonal monoestry. Despite extensive fragmentation of the original rain forest, a species-rich bat assemblage still exists in the landscape studied. Short distances among remaining forest fragments and man-made hab- itats seem to facilitate persistence and reproductive connectivity among members of this bat assemblage.