Wildlife mortality data:
Between road kill, “removal” killing by State Game and Fish and Federal Fish and Wildlife Services, and legal hunting/trapping, the human caused mortality of wildlife adds up. Add in illegal/out of season hunting (poaching), and the numbers soar even higher. Then there is the natural death of wild animals, and the un-natural death due to human caused degradation and disruption of habitat, water supply, vegetation, etc. So the majority of animal deaths may go undocumented or unseen. Yet each year known numbers can be tallied up and compared to give some clues as to the total population movement. This gets tricky though, as lower total mortality numbers may mean a declining population, or it may mean a growing population, depending on how the killing is taking place. Higher mortality numbers may mean an increasing population, or it may mean a declining one. If the mortality numbers remain constant over a period of years, the population may be steady and “balanced”, or it may be nearing a collapse as the last of its numbers succumbs and is drawn in to human dominated areas. As some big cat population numbers decline, the females can start to kill their own cubs, further weakening total numbers, but maybe as a way to survive themselves for another year.
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The news on Black Bears from the state of NM, so far this year:
New Mexico Department of Game and Fish
2014-15 Bear Depredation and Roadkill Update
Compiled by: Rick Winslow, Bear and Cougar Biologist
Note: of 22 total bears killed to date, 6 (27.3%) have been female. This number includes depredation (12) and roadkill (10).
June 12, 2014
And the 2013 data from “Wildlife Services” division of the U.S.D.A. is linked here: http://www.aphis.usda.gov/wildlife_damage/prog_data/2013/G/Tables/Table%20G_ShortReport.pdf
No Black Bears killed in NM in this report, but 11 cougars were.
All this to highlight the fact that getting reliable documentation on wildlife populations is difficult at best, and nearly impossible for most. This is why most efforts at conservation have focused on habitat improvement and protection, but these data on actual numbers are always important, so when we have the opportunity to document road kill or hunting/trapping data, or sampling DNA from depredation kills, we should do so. All these data can give us clues and further inform the population mystery.
Read the next post to see how all this ties in to something more real than just an intellectual grasp of animal population numbers, and relates to how conservation measures can be taken in a very practical way.