Basically, after finishing my PhD transfer report I showed my work (all the output from my jaguar population model) to my collaborators in Belize - researchers who have been working with jaguars for years, I found that some of the key outputs from the model were not close enough to realistic values for jaguar populations in the wild. Namely, territory sizes and the distances that individuals moved over time. Those things that seemed pretty critical to the emergence of a stable population size. In fact, upon initial attempts to increase territory sizes, my stable population became stable no longer. Hence, I've spent the last 3 months re-doing all the tedious trial and error work I did during the previous 3 months in trying to get a stable population size over time that exhibited more realistic individual behavioural characteristics.
I've just about finished doing all the work and getting all the output. Ive harnessed the power of 2 computers at the university to do the bulk of the simulation work which I have managed to get remote access to. This has made the whole thing a lot easier as I don't have daily access to the computers in person. This has also freed up my own computer to do some other work - the work I should have been doing over the past 3 months instead of re-doing the population model.
So, perhaps I am jumping the gun a bit here as I have yet to fully analyse the output or run it past my field collaborators, but these are the current model parameter settings. First is the least-cost model, and food availability:
Then comes the interaction parameters:
In short, parameters I've changed are:
- the *number of time steps per day* - from 4 to 10;
- the *number of cells males can move when trying to find a female to mate with* - from a maximum of 10 to a max of 25;
- the *pheromone degrade rate* - to 0.08;
- the *cost of male pheromone to a female* - from p to 0.3*p;
- the *cost of a male pheromone to another male, if the males are on a trail* - from p to -0.001*p;
- *food availability* outside of Cockscomb protected reserve - reduced to 85% of the availability inside CBWS;
- addition of a *post-model setup* period - the initial 10 years (including the 3-year startup period) describe a reduced mortality for all adults, allowing greater time for the population to find suitable territories.
Initial analyses give male territories from around 40 to 70km2 and females around 10-20km2. These seem much closer to realistic sizes. Population sizes also seem to settle around 70-120 in number which also seem pretty good for the location.
These settings also seem to generate larger numbers of individuals being captured by the static model camera traps. Original stats gave an average of around 5 per sampling period versus the 191 collected in the field which is pretty bad. The new settings don't give anything near 191 either, but closer to an average of around 20ish.
Some other points:
- Females undergo typical reproductive rates, being available to mate only for the central third of their oestrus cycle;
- sub-adults leave the mother aged 2 and undergo a single year of 'dispersal' during which time they can move freely within their mothers range, are reproductively inactive and experience a higher mortality rate;
- dispersal is therefore an emergent feature of the model and not hard-coded.
We'll see what the final analysis looks like soon and take it from there.
