Microsoft PowerPoint Portada taller Jaguares

Male Breeding Pool: In many species, some adult males may be socially restricted 

from breeding despite being physiologically capable. This can be modeled in 

VORTEX specifying a portion of the total pool of adult males that may be 

considered "available" for breeding each year. We assumed that each adult male is 

equally capable of establishing a territory and, therefore, is equally capable of 

breeding in a given year. This is not to say, however, that every male is actually 

successful in that same year. Stochastic variation in the number of females that 

breed, as well as the annual fluctuations in the total number of adults, may lead to 

some males being unsuccessful. 

Mortality: We developed the following simple age-sex specific mortality schedule, 

based primarily on experience with other large felids (environmental variation (SD) 

in parentheses): 

Age % 

Mortality 

 

0-1 

1-2 

2-3 

3- 

50(15) 

30(4) 

10(3) 

10(3) 

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Detailed field studies using radio-telemetry will be needed to determine 

population-specific rates of mortality over a period of3-4 years. In addition, note 

that we are assuming that these mortality rates apply to both males and females. 

This may not be a valid assumption as males may experience higher mortality 

through competition. This can be addressed in more detail in later modeling 

efforts. 

Inbreeding Depression:  VORTEX includes the ability to model the detrimental 

effects of inbreeding through reduced survival of jaguar cubs through their first 

year. While we did not include these detrimental effects of inbreeding in our 

baseline model, we did add it in subsequent model s in order to evaluate its impact 

(see below). 

Initial Population Size: For the purposes of this exercise, we arbitrarily set the 

starting population size at 70 individuals. VORTEX then distributes the specified 

initial population among age-sex classes according to a stable age distribution that 

is characteristic of the mortality and reproductive schedule described previously. 

Carrying Capacity: The carrying capacity, K, for a given habitat patch defines an 

upper limit for the population size, above which additional mortality is imposed 

randomly across all age classes in order to return the population to the value set 

for K. 

Once again, we arbitrarily set K to be 150 individuals in order to allow a 

population to grow larger than its initial size if rates of birth and death rates 

dictated. It is currently unclear if most isolated wild jaguar populations are at or 

below carrying capacity. 

Iterations and Years of Projection; All scenarios (defined as a single set of unique 

input data) were repeated 100 times, with population projections extending to 50 

years. All simulations were conducted using 

VORTEX 

version 8.41 (June 2000). 

Features of the Model Not Included Here: In order to keep the demonstrations 

simple at this workshop, a number of features within 

VORTEXWQTQ 

not included in 

the process of developing population models. These features include: 

• Density-dependent breeding; 

• Catastrophes - natural or man-made - that can dramatically reduce birth and 

death rates for brief periods of time; 

• Age-specific reproductive rates among adult females; 

• Time-specific changes in reproductive rates or habitat characteristics. 

More detailed modeling efforts in the future may include these factors as 

additional field data becomes available. 

 

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Results From Simulation Modeling 

The input data described above constitutes what we call our baseline model. This 

model serves as the foundation to which all other models are compared so that we 

can determine the response of our simulated jaguar population to changes in one 

or more input parameters. 

The output from our baseline model is shown below in Figure 1. This plot shows 

100 iterations (replicated simulations) as well as summary information about the 

model above the graph. Note that, because of the addition to the model of annual 

random variation in birth and death rates, no two individual replicate trajectories 

are alike. As a result, it is important to run a number of simulations (e.g-, a 

minimum of 100 is common) in order to evaluate both the most likely outcome as 

well as the range of possible outcomes. 

 

Figure 1. Population 

trajectories from the 

VORTEX 

baseline 

Mesoamerican jaguar 

population model. 

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It is apparent from this graph that the population is able to grow in size over time; 

the annual rate of growth (specified by r) is estimated to be more than 4%. 

Moreover, none of the populations decline to extinction during the 100-year time 

frame of the simulation. Therefore we can conclude that, under the specific 

conditions that we assumed for this model, this simulated population has a high 

probability of persistence through time. In order to investigate the impact that adult 

mortality can have on overall population dynamics, we can develop a second model 

in which the average rate of adult male and female mortality is increased from 10% 

to 15%. Because all other input is unchanged, this particular model will allow us to 

evaluate this parameter in detail. 

 

 

 

^^o-ri

 

The results of this second model are shown in Figure 2. Immediately apparent from 

this graph is the decreased rate of growth among replicate populations. Specifically, 

the growth rate is reduced from 4% in the baseline model to just 1% in the model 

with higher adult mortality. Perhaps more importantly, there is now a risk of 

population extinction associated with this lower rate of population growth - six of 

the 100 replicate population declined to zero within 70 years. Clearly, this reduced 

rate of adult survival has a significant impact on the general health of a population 

and its continued persistence. Using methods of analysis such as this, we can 

identify those demographic parameters that play a major role in driving population 

dynamics. Consequently, we can use this information to design detailed field 

studies to provide researchers and managers with confident estimates of these 

parameters for use in future population viability analyses. 

Finally, we can investigate the impact that inbreeding and its detrimental effects on 

cub survival can have on overall population viability. The results from this model 

are shown in Figure 3. As is evident from the graph, the impact of inbreeding 

depression is even more striking, leading to a strong decrease in population growth 

rate and a large increase in population extinction probability. In fact, the average 

population growth rate is now negative, indicating that the expected population 

projection will show a gradual decline in population size over time. Clearly, 

Figure 2. Population 

trajectories from a 

VORTEX 

Mesoamerican jaguar 

population model in which adult 

mortality is increased from its 

baseline value of 10% to 15%. 

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