Monitoring Mammal Populations in Costa Rican Protected Areas under Different Hunting Restrictions

Abstract

It is necessary to assess whether the management of protected areas is achieving the objectives set for them. In particular, changes and trends in wildlife populations should be documented. We compared the 1990 abundance of mammals in two Costa Rican protected areas, Corcovado National Park (CNP) and Golfo Dulce Forest Reserve (GDFR), with similar environmental characteristics but different hunting restrictions and levels of protection. We also monitored the abundance of mammals in CNP over a 4-year period. We also devised an inexpensive method of monitoring tropical rainforest mammal populations in a timely and efficient manner. The method is based on the use of mammal track records and arboreal mammal sightings and requires little effort. With this method 20 mammal species were recorded at CNP and 15 at GDFR. Species were consistently less abundant in GDFR than in CNP, principally those species preferred by hunters. Species were grouped according to whether or not they are used as food and whether they are locally or globally threatened or not threatened. The abundance of all these groups of species in GDFR was 6-28% the abundance in CNP. During 1990During -1994, overall mammal abundance in CNP remained relatively stable, but there was considerable variability among species. As a group, both species used for food and globally threatened species declined in abundance during that period in CNP. The abundance of all groups of species declined from 1992 to 1994, coinciding with a reduction in hunting vigilance at CNP. Evidence suggests that the main factor differentiating the abundance of mammals in the two protected areas, and at CNP during the study period, was the level of hunting. Golfo Dulce Forest Reserve seems to be achieving only partial success in protecting wildlife, whereas Corcovado National Park seems to be considerably more effective, although not entirely successful. Monitoreo de Poblaciones de Mamíferos en Áreas Protegidas de Costa Rica con Diferentes Restricciones de CaceríaResumen: Es necesario evaluar si el manejo de áreas protegidas está cumpliendo con sus objetivos establecidos. En particular, se deben documentar los cambios y tendencias de las poblaciones de vida silvestre. En este estudio comparamos la abundancia de los mamíferos durante 1990 en dos áreas protegidas de Costa Rica con características ambientales semejantes, pero con diferentes restricciones en cuanto a la cacería y diferentes niveles de protección: el Parque Nacional Corcovado (PNC) y la Reserva Forestal Golfo Dulce (RFGD). También comparamos la abundancia de los mamíferos en el PNC durante un periodo de cuatro años (1990)(1991)(1992)(1993)(1994). Además desarrollamos un método barato, basado en el registro de huellas de mamíferos y en avistamientos de mamíferos arborícolas. Este método requiere de poco esfuerzo y se puede usar para dar seguimiento a las poblaciones de mamíferos selváticos de manera rápida y eficiente. Con este método registramos la abundancia de 20 especies en el PNC y de 15 en la RFGD. Todas las especies f...

An Evaluation of Threatened Species Categorization Systems Used on the American Continent

“…Some of the characteristics used in these systems-for example, reproductive characteristics (number of offspring per year or age at first reproduction)-are not easily obtained. The effect of human activity is also difficult to obtain because the same activity can affect different species in different ways (Carrillo et al 2000;Cuarón 2000). This type of systems tends to evaluate the potential vulnerability of a species rather than its actual conservation status.…”

Human disturbance impacts on rainforest mammals are most notable in the canopy, especially for larger‐bodied species

“…Despite forest disturbance being widely regarded as detrimental to tropical biodiversity as a whole (e.g., Gibson et al, 2011), recent evidence suggests that tropical mammals may be resilient to some intermediate forms of habitat modification, such as selective logging of tropical forests (Gibson et al, 2011;Putz et al., 2012;Tobler et al, 2018). However, the majority of assessments conducted to date either rely on terrestrial camera traps (e.g., Roopsind, Caughlin, Sambhu, Fragoso, & Putz, 2017;Wearn et al, 2017), which under-represent arboreal species, or on ground-based transect techniques (e.g., Carrillo, Wong, & Cuarón, 2000;Lopes & Ferrari, 2008), which are typically biased towards large, conspicuous, diurnal species and often miss cryptic and nocturnal arboreal species (Bowler, Tobler, Endress, Gilmore, & Anderson, 2017;Kays & Allison, 2001;Whitworth, Braunholtz, Huarcaya, Macleod, & Beirne, 2016).…”

“…Ground-based transect techniques have demonstrated that largebodied primates are more susceptible to human disturbance (especially from hunting) than their smaller-bodied counterparts, likely due to their size and slow reproductive rates (Carrillo et al, 2000;Lopes & Ferrari, 2008;Sampaio, Lima, Magnusson, & Peres, 2010), however very little is known about the responses of arboreal mammal communities as a whole (Kays & Allison, 2001). The inherent bias in survey techniques targeting mammal communities has thus far kept the challenge of characterizing community-level responses to forest degradation in complex tropical rainforest environments beyond the reach of conservation science.…”

Impact of Hurricane Dean (2007) on Game Species of the Selva Maya, Mexico

“…SAMPLING METHODS.-Surveys by direct observation of small populations or of rare, nocturnal, evasive and cryptic species, can result in no-detection errors or false absences (i.e., failure to detect a species when present). An alternative in the case of low fauna detectability in tropical regions is the sampling of tracks and signs as a noninvasive method (Carrillo et al 2000, Silveira et al 2003. Track surveys are widely used because they are relatively easy to implement, are low cost, and do not require the detection of individuals at a specific time of sampling (Wilson & Delahay 2001, Lyra-Jorge et al 2008, Roberts 2011).…”

“…DATA ANALYSIS.-The relative abundance of each species for each sampling period was obtained using the index of RTA, which is derived from the number of tracks or signs of a given species per kilometer walked. The index allows comparisons of RTA under different spatial and temporal circumstances and for different groups of fauna, ranging from ungulates to large rodents, mammals, and birds (Carrillo et al 2000, Wilson & Delahay 2001, Krebs 2006). We chose RTA as a mean to evaluate changes in the species to reduce errors of detectability (Engeman 2005, MacKenzie et al 2011.…”