Off-campus UMass Amherst users: To download campus access dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Dissertations that have an embargo placed on them will not be available to anyone until the embargo expires.

Author ORCID Identifier

https://orcid.org/0000-0002-3652-7694

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Environmental Conservation

Year Degree Awarded

2021

Month Degree Awarded

May

First Advisor

Todd Fuller

Second Advisor

Eduardo Carrillo

Third Advisor

Jason Kamilar

Subject Categories

Population Biology

Abstract

Jaguars (Panthera onca) are a landscape species persisting in less than 54% of their historical distribution range; thus, the understanding of abiotic and biotic environmental factors affecting ecological interactions of this top predator in seasonal ecosystems such the dry forest is crucial for their conservation. In addition to factors affecting species ecology, some methodological constraints also could affect jaguar study outcomes leading to wrong decision-making. Data gathered from available jaguar peer-reviewed literature showed that there are large number of variables and techniques used to model jaguar distribution that did not contribute substantially to descriptions of jaguar distribution. Using the variables that do correlate with distribution (or better estimates of those variables or what they represent) such as prey abundance, protection level, distance to protected areas, landcover, road variables and vegetation, would improve estimates of jaguar distribution and abundance based on intuitive predictors. Therefore, researchers should better identify and then quantify specific casual factors affecting jaguar distribution and abundance, rather than simply describe it. Camera trap data at waterholes and pathways in Santa Rosa National Park in northwestern Costa Rica were evaluated that included two camera trap designs (50 camera traps at waterholes and on pathways during both dry/wet seasons). For 10 large mammal species (including jaguars) and four large bird species in the dry forest of northwestern Costa Rica, only capuchin monkeys (Cebus capucinus), tiger herons (Trigrisoma mexicanum), white-tailed deer (Odocoileus virginianus), and tapirs (Tapirus bairdii) showed interacting effects of location and seasonality, suggesting that these species were the most influenced by waterholes during the dry season. Data from a single female jaguar equipped with a GPS unit, and seasonal sea turtle abundance data and predation rates from track count surveys at Playa Naranjo and Playa Nancite, were analyzed to assess jaguar dependency on nesting turtles. Seasonal movements of this single female were influenced by seasonal sea turtle abundance availability, an overall home range size of 89 km2 did not differ statistically across turtle and non-turtle seasons, and during turtle seasons this collared female tended to stay mostly near the coastline. With regard to camera placement and seasonality on photo rates of jaguars and nontarget species, from June 2016 to June 2017 I deployed 58 camera traps at trail and off-trail locations in a grid array. I recorded 64 species of amphibians, reptiles, birds and mammals for which I calculated and compared relative abundance indexes (RAI: no. of independent photos/100 trap nights). For jaguars, I identified a high RAI of males at trail locations and high rates of female jaguars at off trail locations. Analysis of predator and prey interactions indicated temporal avoidance at trail locations. Density estimation using spatial capture-recapture models registered 19 jaguar individuals (11 males; 8 females), and a population density of 2.6/100 km2 (95% [CI] 1.7-4.0) jaguar females and 5.0/100 km2 jaguar males (95% [CI] 3.4-7.4). Camera location placement might bias sex individual detections and subsequent estimates based on telemetry and camera trap data. Long-term studies of jaguar populations might give more realistic and useful insights to conservation if researchers paid more attention to species’ behavior and interactions that could be biasing results. Thus, it is important to continuously rethink the “what?” and “how?” of the things we are doing in conservation science to effectively understand ecological processes. Additional observations from this study suggest some large herbivores are more sensitive to changes of climate than other species; therefore, jaguar studies should continue to tackle the effects of climate variability on prey species and their relationships with large predators in a unique ecosystem such the tropical dry forest.

DOI

https://doi.org/10.7275/20688859.0

Download

Share

COinS