ME141 Bird diversity & distribution in relation to forest structure in the Calakmul Biosphere Reserve, Mexico
The Calakmul Biosphere Reserve has extremely high bird diversity with over 360 resident bird species, many of which are endemic. Due to the traditional farming methods of the Ancient Mayans and their direct descendants living in the buffer zone of the reserve, Calakmul contains a large expanse of old growth forest in the core zone, and old growth forest and regenerating forests of various ages in the buffer zone. In addition, there is a notable rainfall gradient from the north to the south of the reserve that results in a gradual change in forest structure and tree species composition. Diversity of forest dwelling birds generally decreases with forest disturbance, but a study from one buffer zone community in Calakmul unexpectedly found that both bird abundance and diversity remained constant across regenerating forests of various ages and old growth forest. As the first Mayan settlers arrived in the Calakmul region before the forest appeared (the climate was too dry to support forest until relatively recently), it is possible that the bird population has evolved with the Mayan farming methods and thus the birds have adapted to using all forest types. The abundance and diversity of birds in Calakmul can be monitored using point counts and mist netting at multiple research locations in the reserve. These data will be collected across a range of transects in the reserve that encompass different habitat characteristics. Each transect contains a number of 20m x 20m habitat survey plots that provide detailed information of the forest characteristics in the area. In each of these plots, tree species will be identified, tree DBH, understorey vegetation, canopy openness, and the number of saplings will be measured. Bird data from each transect can then be related to mean habitat characteristics for the transect and comparisons between bird diversity and habitat variables may be investigated.
ME142 Herpetofaunal species distribution and niche partitioning in the Calakmul Biosphere Reserve, Mexico
The herpetofauna of the Yucatan Peninsula is diverse and contains a high percentage of endemic species that have evolved to adapt to the unique forest habitat. Despite this, the herpetofauna of the Calakmul Biosphere Reserve is poorly studied. There is a notable rainfall gradient from the north to the south of the reserve, which significantly affects tree diversity and forest structure. The only source of water in the reserve comes from lakes known as aguadas. Some are permanent, but the majority are temporary that form on low lying ground during the rainy season. This variation in habitat is likely to have a notable effect on the abundance and distribution of herpetofauna within Calakmul. Herpetofauna surveys will be conducted at five different research locations within the reserve that have notable differences in habitat type. Within each location, herpetofauna will be surveyed using pitfall traps and diurnal and nocturnal active searching along transects. Students will also assist with habitat surveys in which tree diversity, tree DBH, understorey vegetation, leaf litter and sapling density are recorded in a selection of 20m x 20m forest plots at each survey location. Research projects could therefore investigate differences in herpetofaunal species assemblages between different sites and in relation to distance from aguadas. These projects could incorporate a wide range of species or could focus on specific groups (e.g. anurans, lizards, snakes). Alternatively, projects could focus on herpetofauna community structure in aguadas of varying sizes. These projects would involve timed searches of the aguadas for amphibian species combined with trapping surveys for lizards, snakes, turtles and crocodiles.
ME143 Large mammal abundance and distribution patterns in relation to habitat characteristics and hunting in the Mayan forest
Large mammal density at Calakmul Biosphere Reserve is very high and the forest is one of the last remaining strongholds of endangered mammals such as spider monkeys, jaguar and tapir. Although these species are not hunted, indigenous people are allowed to hunt other large mammals such as peccary and deer (which are the preferred prey of jaguar and puma). The tropical semi-deciduous forest in the Calakmul Biosphere Reserve is unusual in that areas close to the Mayan Ruins contain unusually high densities of large fruiting trees (the result of Ancient Mayan agroforestry) in comparison to other areas. As there are no rivers or streams in the reserve, forest structure is also heavily affected by distance from the few permanent water sources in the reserve known as aguadas. The aim of the large mammal research project is to investigate the relationship between habitat characteristics and large mammal abundance and ranging, and to investigate the impact of hunting of preferred prey species on the abundance and distribution of felids. Mammal abundance data will be collected along a series of forest transects using distance sampling (based on visual sightings of more commonly encountered species such as primates) and patch occupancy sampling (based on tracks and signs of more elusive species such as tapir and jaguar). Additional data will be collected using camera traps enabling comparison of density estimates produced by the different types of surveys. The survey transects are distributed across a wide range of forest habitat types and each transect contains a number of 20m x 20m habitat survey plots. In each of these plots, tree species will be identified, and DBH and tree height will be measured. Large mammal data from each transect can then be related to mean habitat characteristics for the transect and comparisons between mammal abundance and habitat variables may be investigated.
ME144 Spider monkey grouping patterns, habitat use and behaviour
Spider monkeys are frugivorous primates that live in complex societies characterised by high degree fission-fusion dynamics whereby members of the same community are rarely all together and spend their time in fluid subgroups that constantly change in size and composition. Subgroup size is adjusted to food patch size and when fruit is abundant the spider monkeys can be found in large groups. Group size and composition can have a notable effect on activity budgets, ranging and social interactions, particularly as there are notable sex-differences in the quality of social relationships and the type of social interactions exchanged by males and female. A large community of spider monkeys in the Calakmul Biosphere Reserve has been studied each summer since 2013. The summer months are associated with the onset of rainy season and high fruit production resulting in large subgroups of spider monkeys. However in 2014 the reserve suffered a severe drought and during this time virtually no fruit was available. Using the long-term data set students can investigate changes to ranging patterns, subgroup composition and the associated effect on rates of social interactions in relation to rainfall patterns and food availability. Another project could focus on spider monkey activity and habitat use. Spider monkeys can have large home ranges that encompass different forest types, but it is not clear if they use all forest types for food and shelter. An investigation of how spider monkeys use the different forest types will determine whether spider monkey populations could survive in disturbed areas with limited availability of high forest. Activity budget data will be recorded using instantaneous scan sampling, noting the behaviour of each individual in view, the GPS location and forest type. Subgroup composition will be recorded in real time throughout the day and all occurrences of social interactions will be recorded noting the individuals involved, behaviour and context.
ME145 Bat abundance, diversity and distribution patterns in relation to habitat characteristics of the Mayan forest
Bat abundance in the Calakmul Biosphere Reserve is very high due to the presence of multiple caves that act as roost sites. There are over 90 bat species that occur in tropical Mexico, but the presence of the majority of these species in Calakmul remains unclear due to lack of standardized studies. Moreover, bat diversity is unlikely to be uniform throughout the reserve due to changes in the habitat resulting from vicinity to ruins sites (Mayan ruins contain unusually high densities of large fruiting trees as a result of Ancient Mayan agroforestry) and the limited water supply in the reserve. Students will investigate bat abundance and diversity using mist net surveys in conjunction with bat detectors that record bat vocalizations. These combined methods will provide data on the carnivorous, frugivorous and nectivorous bats that are frequently caught in the nets and the insectivorous bats that have such fine-tuned echolocation that they can detect mist nets and are therefore virtually impossible to capture. These data will be collected across a range of transects in the reserve that encompass different habitat characteristics. Each transect contains a number of 20m x 20m habitat survey plots that provide detailed information of the forest characteristics in the area. In each of these plots, tree species will be identified, tree DBH, understorey vegetation, canopy openness, and the number of saplings will be measured. Bat data from each transect can then be related to mean habitat characteristics for the transect and comparisons between bat diversity and habitat variables may be investigated.