Tapir population patterns under the disappearance of free-standing water

Abstract

Baird's tapir is the largest Neotropical tapir species, and it is considered Endangered by the IUCN. The Calakmul Biosphere Reserve (CBR) is the largest protected tropical forest in Mexico. The CBR is at the heart of the Maya Forest, a tri-national forest located in Mexico, Guatemala, and Belize that is the largest tropical forest outside the Amazon River basin. Free-standing water in the CBR occurs in only a few ephemeral ponds. These ponds are rare in the landscape, with a mean density of one pond in every 10 km 2 , and with an average distance among ponds of 3 km. Only some of these ponds have free-standing water in every year. A decreasing trend in water availability from these ponds was detected from 2008 to 2018. Our present objective was to document population of the tapirs during these 11 years, and reveal any relationship to the pattern of water availability. Using the technique of photo-trapping, we monitored from 9 to 15 ponds over a period of 8 years (a total of more than 18,000 camera-days) during the 11-year period. Results showed that although the population remained relatively stable, the index of relative abundance indicated a slight decrease in population abundance and in some sites seemed at least superficially associated with decreasing water availability. Such long-term population studies are becoming more important for estimating the impacts of possible changes and for predicting the future of populations. In turn, they assist the conservation of endangered and sensitive species such as Baird's tapir. El tapir de Baird es el más grande de las especies de tapires Neotropicales y está considerado como en peligro por la UICN. La Reserva de la Biosfera de Calakmul (CBR por sus siglas en ingles) es el área de bosque tropical protegido mas grande de México y se encuentra en el corazón de la Selva Maya, un bosque tri-nacional localizado entre Belice, Guatemala y México considerado el bosque tropical mas extenso de Mesoamérica. El agua de lluvia en la CBR percola al subsuelo y solamente en pocos sitios (localmente conocidos como aguadas) se almacena agua en el suelo. Estos sitios son raros en el paisaje con una densidad de uno cada 10 km 2 y una distancia promedio de 3 km entre aguadas. Solamente algunos de esos sitios conserva agua durante la época seca de cada año. Se detectó una reducción de la disponibilidad de agua desde el 2008 al 2018. Documentamos la población de tapires durante estos años y examinamos la relación con este patrón de reducción de la disponibilidad de agua. Usando la técnica de foto-trampeo monitoreamos entre 9 a 15 aguadas en 8 años dentro de este periodo de 11 años. Con un total de mas de 18,000 días-cámaras encontramos que aunque la población de tapires de la CBR permanece estable en promedio el índice de abundancia relativa detectó una ligera disminución en la abundancia y en algunas aguadas se asoció con la falta de agua. Estudios de largo plazo de especies en peligro asociadas a cuerpos de agua son importantes porque permiten estimar los efectos de la disponibilidad de a...

Occupancy rate and observations of Baird’s tapir (Tapirella bairdii) near waterholes in the Maya forest corridor, Belize

“…Slight increases in occupancy and detections rates were seen from 2015 and 2019, which can be attributed to unusually extended dry seasons in central Belize (Meteorological Service of Belize 2020). This study is similar to a 11-year study conducted at another site in the Maya Forest, the Calakmul Biosphere Reserve in Mexico (Reyna-Hurtado et al 2019), where tapir occupancy rate was relatively constant despite huge variations on water availability on the forest floor. However, caution should be taken when applying occupancy results as an alternate for tapir abundance.…”

“…More collaborative efforts on systematic research designs are essential not only for the conservation of tapir habitat but also for an understanding of waterhole usage dynamics. We propose a collaborative effort with the Belize Forest Department and Government of Belize in the installation of water containers on strategic waterholes like the Calakmul, Mexico model (Reyna-Hurtado et al 2019). The continued monitoring of tapirs at waterholes on a long-term basis and with an increased sample size of waterholes and non-waterholes is also important.…”

“…Despite tapirs' level of extinction threat and their ecological and evolutionary relevance, there are critical gaps in our understanding of their basic ecology such as habitat use, habitat selection, spatial ecology and population demography (García et al 2012). The availability of water resources in the Maya Forest has increasingly become indispensable for ungulates of concern such as Baird's tapir (Reyna-Hurtado et al 2019) and white-lipped peccary (Moreira-Ramirez et al 2016). Due to the fact that water can be a limiting factor to Baird's tapir populations (Krausman and Etchberger 1995;Cain et al 2006;Krausman et al 2006), and that the dry season (December to May) is becoming et al (2016), we used a selection criterion of less than 24 hour intervals between camera capture events for considering independence.…”

Interference competition between Pecari tajacu and Odocoileus virginianus

“…The Calakmul region is characterized by marked seasonally changes between rain and dry season, and by lacking running water bodies and the only source of water are ephemeral ponds known locally as "aguadas" (García-Gil 2002, Reyna-Hurtado et al 2010). In the years 2015 to early 2020, a dry period impacted the with annual precipitation below average and caused several waterholes not to fill enough water and some of them dried up (Reyna-Hurtado et al 2019, Zúñiga-Morales & Sima-Panti 2015, Mardero et al 2012. This situation probably caused that a limited resource such as water can increase the encounters among species and consequently the competition processes such as the ones we observed between the collared peccary and the white-tailed deer (Sanchez-Pinzón et al 2020).…”

Morelet’s crocodile predation by jaguar in the Calakmul Biosphere Reserve in southeastern México

“…The aguadas in CBR are the main source of water, both for wildlife and for humans. A study by Reyna-Hurtado et al (2019) mentions that the availability of water in the reserve was drastically reduced in early 2018. The level of aguadas in recent years has reduced due to the decrease in precipitation and the prolonged droughts.…”