Ada Sánchez-Mercado

Factors affecting poaching risk to Vulnerable Andean bears Tremarctos ornatus in the Cordillera de Mérida, Venezuela: space, parks and people

Worldwide, many large mammals are threatened by poaching. However, understanding the causes of poaching is difficult when both hunter and hunted are elusive. One alternative is to apply regression models to opportunistically- collected data but doing so without accounting for inherent biases may result in misleading conclusions. To demonstrate a straightforward method to account for such biases, and to guide further research on an elusive Vulnerable species, we visualized spatio-temporal poaching patterns in 844 Andean bear Tremarctos ornatus presence reports from the Cordillera de Merida, Venezuela. To create maps of poaching risk we fitted two logistic regression models to a subset of 287 precisely georeferenced reports, one ignoring and one including spatial autocorrelation. Whereas the variance explained by both models was low, the second had better fit and predictive ability, and indicated that protected status had a significant positive effect on reducing poaching risk. Poaching risk increased at lower altitudes, where all indicators of human disturbance increased, although there was scant evidence that human-bear conflicts are a major direct trigger of poaching events. Because highest-risk areas were different from areas with most bear reports, we speculate that hunting may be driven by opportu- nistic encounters, rather than by purposeful searches in high- quality bear habitat. Further research comparing risk maps with bear abundance models and data on poaching behaviour will be invaluable for clarifying poaching causes and for identifying management strategies.

Congruence and Diversity of Butterfly-Host Plant Associations at Higher Taxonomic Levels

We aggregated data on butterfly-host plant associations from existing sources in order to address the following questions: (1) is there a general correlation between host diversity and butterfly species richness?, (2) has the evolution of host plant use followed consistent patterns across butterfly lineages?, (3) what is the common ancestral host plant for all butterfly lineages? The compilation included 44,148 records from 5,152 butterfly species (28.6% of worldwide species of Papilionoidea) and 1,193 genera (66.3%). The overwhelming majority of butterflies use angiosperms as host plants. Fabales is used by most species (1,007 spp.) from all seven butterfly families and most subfamilies, Poales is the second most frequently used order, but is mostly restricted to two species-rich subfamilies: Hesperiinae (56.5% of all Hesperiidae), and Satyrinae (42.6% of all Nymphalidae). We found a significant and strong correlation between host plant diversity and butterfly species richness. A global test for congruence (Parafit test) was sensitive to uncertainty in the butterfly cladogram, and suggests a mixed system with congruent associations between Papilionidae and magnoliids, Hesperiidae and monocots, and the remaining subfamilies with the eudicots (fabids and malvids), but also numerous random associations. The congruent associations are also recovered as the most probable ancestral states in each node using maximum likelihood methods. The shift from basal groups to eudicots appears to be more likely than the other way around, with the only exception being a Satyrine-clade within the Nymphalidae that feed on monocots. Our analysis contributes to the visualization of the complex pattern of interactions at superfamily level and provides a context to discuss the timing of changes in host plant utilization that might have promoted diversification in some butterfly lineages.

A NATION-WIDE STANDARDIZED BIRD SURVEY SCHEME FOR VENEZUELA

Abstract We developed a field survey protocol based on the North American Breeding Bird Survey to evaluate the efficiency and reliability of a bird monitoring scheme in the Neotropics, known as NeoMaps. A team of 21 amateur and professional ornithologists conducted bird counts at 27 locations distributed throughout Venezuela between March and April 2010. Locations selected followed a stratified spatial sampling design derived from environmental and biogeographical variables. Two complementary survey protocols were implemented in consecutive days along 40-km-long roadside transects. Three-minute point counts were performed at 50 stops, 800 m from each other on day 1. Cumulative species lists were recorded at a selection of 10 stops sampled for 9 min each, divided into three consecutive 3-min periods on day 2. We recorded 593 species at the 27 sites combined, representing 57% of the 1,033 potential species, or 43% of all known Venezuelan species. An additional 83 species were recorded outside of the formal point counts, for a total of 676 species detected. Groups such as hummingbirds and most waterbirds had unusually low numbers of both species and individuals, probably due to an abnormally dry year. Our survey methods appear to be appropriate for surveying most common diurnal non-colonial species. This is the first large-scale, systematic bird survey in Venezuela or, to our knowledge, in any other tropical country.