There is a critical absence of any consensus on the distribution, extent, and causes of the global amphibian population decline, due to the dearth of short and long-term comprehensive monitoring studies (Wake 1998). Project Anuran is an undergraduate research study which completed its fifth and final year of study in summer 2004 and has collected one of the most comprehensive amphibian population level databases in Belize.
Phases I to IV of the project were concerned with undertaking a comprehensive monitoring programme of the anuran (frog and toad) community in the neotropical area of Las Cuevas, Chiquibul National Park, Belize (see map). However, Phase V of the project, while continuing the anuran monitoring process, also took this research a step further, by expanding the investigation into a very closely-related field: the identification and monitoring of salamander populations around the region of Las Cuevas.
The completion of 5 years of anuran studies will permit the creation of a substantial database, providing a very valuable insight into the levels of spatial and temporal variability in species presence/absence, abundance levels, and reproductive activity. At present, a lack of information on the natural levels of variability in these factors seriously confounds our ability to identify population declines (Pechmann et al. 1991, Gardner 2001). Comprehensive monitoring programmes such as Project Anuran, which considers variability among sites, habitat type, nights, years and species, can make a unique contribution towards providing this information.
The basic questions that concern our programme are:
During field seasons from 2000 to 2004 Project Anuran was able to contribute towards our understanding of these issues by collecting data on the patterns of variability in species assemblage composition, species' relative abundance, reproductive behavior, and environmental associations.
Aside from providing a uniquely comprehensive assessment of amphibian populations, Project Anuran complements similar studies by focusing on an area that remains largely unstudied: there is a desperate need for amphibian studies in neotropical regions (Young et al 2001). Although notable work has been done at high-altitude neotropical sites (Guyer 1990; Lips 1998), very little has been done at lowland tropical and subtropical sites. Belize, which has vast protected areas and retains some 75% of its natural vegetation (Harcourt 1996), and where a large percentage of its amphibian population remaining relatively unknown (Meyer & Foster 1996), presents an ideal location for amphibian population work.
Surveys of the ten chosen breeding ponds were run during the night from 19.00 to 02.00 when possible. The survey of each pond was repeated at least 7 times. Measurements taken on arrival at each pond include depth of pond, pH measurements and a summary weather report. Following this, half hourly recordings of species abundance and calling activity were made. Recordings of air and water temperature, volume of rainfall, duration and number of rainfall events were also made. Measures of abundance follow the MAYAMON protocol (Meyer 1999). The data was geographically located by GPS and will be fed into the GIS for the Natural History Museum for the Chiquibul National Park.
Five transect lines were cut, 500m in length and 2m in width, and surveyed by two people who walk carefuly down the line searching the leaf litter and branches up to eye level on one half of the transect. In order to standardise the search effort a time restraint of one hour was placed on each transect survey, producing an average search speed of 0.5 km per hour. Where possible, a minimum of 5 repeats were conducted per transect, during both day and night.
Bucket pitfall traps were set up in suitable sites around the region of Las Cuevas. Animals were led to the trap by drift fences. The traps were monitored every morning and evening. Identification followed and specimens were be released immediately afterwards, back into the habitats in which they were caught.
Daily recordings will be made at 09.00 of rainfall volume and duration over the previous 24 hours, maximum and minimum temperature, relative humidity and cloud cover. In addition to this, rain gauges were be placed at the Aguada (4 km east of LCRS) and Millionario (5 km west of LCRS) ponds and another at LCRS, creating a cross-sectional map of rainfall. Data collected from these will allow consideration of the spatial variability in rainfall patterns within the study area. Finally, a general vegetation survey was carried out at all the ten breeding sites.
