Thursday, February 28, 2013

Fallible wild animals

More photos by Zac. Penny included for scale
What: On our tracking adventure at Bread and Butter Farm, we were also impressed at the density of coyote sign - they must be snacking on all them li'l rabs. We decided to trail one of the paths for a ways. Pretty quickly, we started noticing blood spots in quite a few places along the trail. Female coyotes are monoestrous (having only one period of "heat" per year). It's relatively short, about 3-5 days and happens sometime between late January and early March, so we got lucky in our timing. The females will scent mark with their urine (which has blood in it). It shows up as small reddish yellow drops on the snow. The female we followed seemed to be on a hunting foray, traveling in mostly straight lines with occasional detours to investigate something that caught her attention (for as long as we followed her, she was unsuccessful in her hunt).

Zac and I both wound up post-holing while trailing her along a small brook that was frozen over. I tend to take clumsiness in humans as a given, but never expect it from wild animals. It's always jarring to see a squirrel miss a branch it's jumping to and fall to the ground, or watch a beaver trip as it's stepping over a rock, or catch a cottontail running into a fence. In this case, not more than 30 yards from where both Zac and I broke through the ice, we saw the tracks in the image above.

It appears like the coyote postholed, then slipped with her right front foot. The track just below the dark circle (the posthole) is her rear foot swinging out wide to steady herself. That 3' provided us with a hundred little stories and questions that we only began to answer as we made our way along the trail over the next half mile or so. It's always refreshing to remember that every now and again wild animal show their fallibility.

Ecological notes: In Centennial Woods there's an abundance of fox (red and gray) and deer, but no coyotes and only a very few rabbits. It made me wonder if there was a correlation between the presence/absence of those species. I found some interesting studies that look into the relationships between these species (as well as bobcats and even Lyme disease). Here's a summary of what I found:
  • Coyotes eat gray foxes (not sure I believe this, or at least that this has a significant impact on gray fox populations)
  • There's an inverse correlation between fox and rabbit populations. Where cottontails are in great abundance, red foxes, an obligate generalist, will shift and specialize in hunting them (study)
  • Bobcats prefer rabbits and rodents and will eat deer second (study)
  • There's an inverse relationship between fox and coyote populations (coyotes apparently bully foxes out of their territories, called interference competition study, another study found that a third of kit foxes radio collared had been killed by coyotes, study)
  • As a result, foxes can be found on the edge of a coyote's territory, but rarely within it
  • Foxes out-compete coyotes in areas where human densities are higher
  • Many predators will kill other predators (canids, it turns out are the most likely predators to kill other species of predators: study)
  • More foxes=less Lyme disease, more coyotes=more Lyme disease (study)
  • Red foxes have a significant impact on the European Roe deer, but those are much smaller than our native deer and it's likely that no such correlation exists
  • Coyotes have a significant impact on deer populations (study)
  • Coyotes are more successful in hunting deer in harsh winters (study)
  • There's no hunting allowed in Burlington, so deer populations may be higher here as a result
  • Deer seek refuge under conifers during winter for warmth, both habitats provide an abundance of hemlock cover, however

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