In a continuation of our last post, where does hunting (or harvest) fit in?
When properly managed and regulated, harvest (be it hunting, trapping, or fishing) can be used to take the place of some forms of natural mortality. Harvest should be a replacing form of mortality, it should replace some of the mortality which occurs naturally. Harvest should NEVER be an additive form of mortality – it should never increase the total mortality above what would happen naturally!
I always learn best when I can see whatever I’m discussing, these graphs seem to help me and I hope they do you as well. Heres one showing how harvest is a GOOD form of mortality; replacing a natural cause:
And in reverse, here is the opposite effect: harvest as an added form of mortality:
So are there any problems with the idea that harvest is a replacing form of mortality? YES!
- Humans do not remove only the sick or old animals as natural forms of mortality normally do.
- Evidence that for some animals (e.g., ruffed grouse, quail) the timing of the harvest (hunting season) may result in harvest becoming an additive form of mortality. Late season hunting may predispose animals to migrating predators or remove lactating females.
This is how wildlife managers such as yourself can manipulate harvest in order to influence wildlife populations. You have to be extremely knowledgeable about your species in order to correctly set harvest limits and dates – and it usually always takes trial and error! As long as harvest isn’t an added form of mortality, its extremely beneficial to the wildlife as well as to the public.