Todays post is mainly just a summing up of model results following some recent analysis that has shook the foundations of my trust in my model.
As it turns out, when you have a complex model, analysing results can be complex and assigning blame to any particular parameter/process can be even more challenging.
I've been happily plodding along in the knowledge that I finally have my model churning out some decent results, with the right things happening at the right time in the right places. One final analysis has turned this on its head with the finding that territory sizes are not properly linked to food resources. I have suspected this has been the case for some time, but following the reduction of food resources outside of the protected area I find that male territories in the matrix are about 3/4 the size of territories inside the CBWS forest. Females surprisingly are the reverse, but I think this is mainly due to most females being driven out of CBWS due to avoidance of males. In the matrix it seems they are able to expand their territories and are not so constrained due to the presence of fewer males. The average size of their territories is also unfeasibly small inside CBWS and nowhere near the size that would be needed in the real world to maintain a single individual....
crap.
So it seems a pretty fundamental feature of my model is not working as it should and I am at a pretty big loss as to why this might be the case.
Looking at males, they are attracted to trails, and attracted to male pheromones on trails. This causes larger territory sizes as they move along trails, pop out further into the forest and create new areas to call their own. Individuals are seemingly not linked to any particular area and territories are completely transitory. I wonder whether this is the problem? Males, due to this feature, also exhibit larger territory sizes when there are more males around, presumably because they get drawn onto trails. However, having a process that allows males to move further along trails causes a population crash in pretty short time (i.e. around year 20 of the simulation). I'm not quite sure why, but I'm doing some tests to figure out if the number of moves makes any difference to the fate of the population.
Looks like I might have to go back to the drawing board.
This is not the news I wanted with 6 months left on my PhD!
What do I want:
Males move along trails where possible
Males follow other males along trails, for some suitable distance.
All individuals have larger territories outside of the protected area as they need to move more to consume sufficient food resources
Females avoid males but generally their territories are overlapped to a large extend by males
Males move much faster along trails
Males move much faster when following a female to mate
All individuals would prefer to be inside the protected area
