Abstract:Plant–animal mutualistic interactions through ecological network systems and the environmental conditions in which they occur, allow us to understand patterns of species composition and the structure and dynamics of communities. We evaluated whether flower morphologies with different pollination syndromes (ornithophilous and non-ornithophilous) are used by hummingbirds and whether these characteristics affect the structure (core-peripheral species) of hummingbird networks. Observations were made in flowering patches, where plant–hummingbird interactions were recorded at three altitudes (300–2500 m) during three seasons (dry, rainy and post-rainy) from 2015 to 2016 at El Triunfo Biosphere Reserve, Chiapas, Mexico. We recorded 15 hummingbird species interacting with 58 plant species, and the greatest number of interacting hummingbird species (11; 14) and plant species (28; 40) were found at middle altitudes and during the dry season, respectively. In all study sites, most of the plant species visited by hummingbirds had an ornithophilous syndrome (67%) at high altitudes (22 plant species) and during the dry season (26 plant species), but more individual hummingbirds visited non-ornithophilous plant species. The hummingbird species at high altitudes exhibited the greatest level of specialization towards plants (H2′ = 0.74), but the networks of plant-hummingbird interactions were generalist (H2′ = 0.25); i.e. visiting plants with both syndromes, at low altitudes. The core generalist hummingbird species remained constant with altitude and season, but the core generalist plant species varied between different altitudes and seasons according to the phenology of the species.

Evidence regarding the ability of agroforests to conserve biological diversity has been mixed; they tend to maintain avian communities with species richness similar to that of undisturbed forest ecosystems but generally do not completely preserve community composition. Using a combination of occupancy modeling and non-metric multidimensional scaling on point-count data, we assessed changes in avian community diversity and composition along a successional gradient in traditional Lacandon Maya agroforests and compared them to protected areas in the region. Bird species richness and diversity in Lacandon agroforests peaked in early secondary forest stages. These agroforests' mean Shannon-Weiner diversity was 5% higher than that of nearby protected areas, but their species richness was similar. Community composition in Lacandon agroforests changed throughout succession, with earlier stages supporting communities distinctly characterized by generalist species, while subsequent, less-intensively managed stages tended to support more forest-dwellers. The bird community observed in even the most mature secondary forest stages in Lacandon agroforests differed from that of undisturbed rain forest ecosystems. These results demonstrate the potential of traditional Lacandon agroforestry management to conserve avian biodiversity while ensuring food sovereignty for farmers. However, because the community composition of early-successional stages was different than later stages, shortening fallow cycles and reducing forest cover to increase agricultural production will limit the species this system can support. This study illustrates the value of incorporating traditional agroecosystems into conservation planning as well as maintaining protected areas, because the latter serve as refugia for species that require undisturbed forest habitat in an agroecological matrix.

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Birds emit alarm calls, considered as honest signals, because they communicate the presence of a predator or potential threat. We evaluated behavioural events of birds responding to vocal and visual stimuli of a nocturnal predator (black-and-white owl Ciccaba nigrolineata) and a diurnal predator (collared forest falcon Micrastur semitorquatus). We analysed variations in behavioural events seasonally (reproductive and nonbreeding) and by bird size, as well as their relationship with the vegetation structure and landscape. The study was performed during the breeding (March-May) and non-breeding seasons (February, June and July) of 2016 in Chiapas, Mexico. We used four transects with different vegetation types and land uses. The most frequent behavioural response by birds to the vocal stimuli of the black-and-white owl and the collared forest-falcons was vocal, during the breeding season, and small species responded the most to the stimuli (p = 0.008) and (p < 0.015), respectively. We identified two vegetation and two landscape variables associated in 36% of probability for the prey to respond to black-and-white owl vocal stimuli, three variables of vegetation and one of the landscape in 37% for the collared forestfalcon stimuli. Potential prey animals modify the behaviour, which allows them to detect, evade or confront a predator.

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