Few reports have described the relationship between the distribution of frugivorous birds and vegetation successional changes in dry forests. We assessed the abundance and behaviour of frugivorous birds in early, intermediate and mature dry forests in the Balsas river basin, Guerrero, Mexico. We selected nine dry-forest fragments, three fragments per stage, in these three stages of succession. We analysed the vegetation, estimated bird abundances in 10-min count periods, and recorded the way birds process fruits in circular plots (11–15 plots per fragment, 123 plots in total). Birds were classified as seed predators (15% of all individuals in this study), pulp consumers (15%) or legitimate dispersers (70%). Bird abundance was higher in mature forests in the dry season, while abundance and richness of legitimate dispersers and seed predators were positively related to vegetation complexity. Mature forests have a high vegetation complexity and a high cover ofBurseraspecies that produce fruit during the dry season. During the rains, abundance was higher in early-successional sites when the zoochorous plants produced fruit. Legitimate disperser migrants (i.e.Tyrannus vociferans, Myiarchus cinerascensandM. tyrannulus) were widespread, helping the establishment of zoochorous trees such asBurseraspp. in early-successional forests.

Vegetation structure and floristics have a strong influence on the relative abundance of spider guilds and functional diversity of terrestrial arthropods. Human activities have transformed much of the temperate woodlands. The aim of this study was to test five predictions related to the guild distribution and functional diversity of the ground spider communities of Eucalyptus plantations and native pine woodlands in western Mexico. Spiders were collected every fortnight from September to November from 15 pitfalls positioned in each of the eight sites. We also assessed the cover of grasses, herbs, shrubs, and leaf litter in each site. We found that the abundances of ground hunters and sheet weavers between plantations and pine woodlands were different. Nevertheless, there was not a consistent difference between sites of each of the vegetation types. Most species of ground hunters, sheet web weavers, and many other hunters were associated with litter and the grass cover. Nonetheless, in some cases, species of different families belonging to the same guild responded to different variables. Wolf spiders were related to the grass Aristida stricta Micheaux, 1803, while the species of the other families of ground hunters were associated with leaf litter. One Eucalyptus plantation and one pine woodland had the highest functional diversity of all sites. These sites have a well developed litter and grass cover. Our study suggests that the abundance of litter and a high cover of grasses explain the occurrence of species with different traits, and these habitat components results in a high functional diversity.

We evaluated the seed dispersal ofBursera longipesby birds along a successional gradient of tropical dry forest (TDF) in southwestern Mexico.B. longipesis an endemic tree to the TDF in the Balsas basin. The relative abundance of frugivorous birds, their frequency of visits toB. longipesand the number of removed fruits were recorded at three study sites with different stages of forest succession (early, intermediate and mature) characterized by distinct floristic and structural elements. Flycatchers of theMyiarchusandTyrannusgenera removed the majority of fruits at each site. Overall, visits toB. longipeswere less frequent at the early successional site. Birds that function as legitimate dispersers by consuming whole seeds and regurgitating or defecating intact seeds in the process also remove the pseudoaril from seeds, thereby facilitating the germination process. The highest germination percentages were recorded for seeds that passed through the digestive system of two migratory flycatchers:M. cinerascensandM. nutingii. Perch plants, mainly composed of legumes (e.g.,Eysenhardtia polystachya, Acacia cochliacantha, Calliandra eryophylla, Mimosa polyantha), serve also as nurse plants since the number of young individuals recruited fromB. longipeswas higher under these than expected by chance. This study shows thatMyiarchusflycatchers are the most efficient seed dispersers ofB. longipesacross all successional stages. This suggests a close mutualistic relationship derived from adaptive processes and local specializations throughout the distribution of both taxa, as supported by the geographic mosaic theory of coevolution.

The biotic province of the Sierra Madre del Sur presents a mosaic of woodlands at different successional stages due to frequent modifications in land use. In this study, we analyzed changes in woody flora across three successional stages of pine-oak forest: early, intermediate, and mature. Vegetation composition and diversity were characterized in 10 plots (each 0.28 ha). The mature stage had the highest values for species richness, abundance, and diversity. Pioneer plants were dominant in the early-successional site and may promote the establishment of late-successional species. The vegetation structure was more complex in the mature stage, where members of the Quercus genus were co-dominant with Pinus species. Pine tree richness was highest in the early-successional stage, and its abundance increased at the intermediate-successional site. These results suggest that Pinus species can grow in perturbed and sunny environments but also require favorable edaphic and microclimatic conditions, such as those found in intermediate woodlands. Results of this fieldwork support the initial floristic composition succession model, which suggests that species present at early stages will also occur in subsequent stages. Ecological succession may be considered to be a natural restoration process, and thus, conservation strategies should focus on maintaining distinct successional communities in addition to mature forests in order to preserve a high number of species.

Mexico has five apicultural regions wich are defined according to their blooming period and geography. Varroa destructor Anderson and Trueman is controlled with pesticides and alternative treatments in all these regions. To determine the concentration-mortality response lines of V. destructor, bioassays with four pesticides that are used for its control in the Gulf of Mexico, Yucatan Peninsula and Central-Highland regions were conducted. The Burgerjon spraying tower was used to apply known concentrations of flumethrin, fluvalinate, amitraz and coumaphos. Lethal concentrations 50 (LC₅₀) and resistance indexes were calculated with Probit analyses. In the Gulf region, the resistance indexes were: flumethrin, 659.43; fluvalinate, 21.83; amitraz, 12.77; coumaphos, 1.49×. In the Central-Highland region: flumethrin, 243.43; fluvalinate, 19.04; amitraz, 8.56; coumaphos, 1.22 x. In the Yucatan Peninsula region: flumethrin, 4057.32; fluvalinate, 199.57; amitraz, 26.55; coumaphos, 3.93×. These results suggest a resistance to flumethrin, fluvalinate and amitraz, with similar values in migratory beekeeping regions, and higher values in the non-migratory region. Coumaphos remained effective in V. destructor populations of the Gulf and Central-Highland regions.

Diet composition and selection of the bighorn sheep (Ovis canadensis) in Sierra El Mechudo, Baja California Sur, Mexico