Saturday, January 16, 2016

Tracking the Wild in Your Neighborhood, Part 2: Fine Feathered Friends

There's one type of trace that I'm guaranteed to see during the winter: raven landing traces. The Common Raven is, well, common in northeastern British Columbia, and is a year-long resident. This is our equivalent to the Rock Dove (or pigeon) in more densely populated areas, or the Black-billed Magpie for my Edmonton, Alberta readers. The ravens here are a clever bunch: they recognize that pickup trucks without canopies are choice opportunities to look for garbage bags, and they are adept at removing both latched and screw top garbage can lids. They also are not shy about landing in the snow.

Cleared for landing!
Look for bird landing traces around bird feeding stations, dumpsters, grain silos, public parks, and garbage cans that people have forgotten to latch down.

This particular unkindness of ravens (which is an unfitting name for ravens, in my opinion) was quite happy to have discovered one such garbage can.

See the tail impression at the top of this image? Right in front of the tail impression are the foot impressions. This raven moved forward a bit right after touching down, and the snow to the left of the foot-body impression shows a wing sweep.

After landing, these ravens spent a great deal of time walking around their garbage treasure. Here we see the classic perching bird footprint shape in these footprints: a long backwards-facing digit (digit 1, or the hallux), the inner digit only lightly splayed away from the middle digit, and the outer digit largely splayed. This similar footprint shape is seen in many perching birds, from ravens to sparrows.

Another interesting feature in raven trackways is that they tend to drag their middle toes (digit III) when they walk.

Sometimes the Black-billed Magpies will join the ravens in their garbage-gutting, or will visit afterwards to pick over the scraps. Here's one Black-billed Magpie landing trace.

Landing traces of Black-billed Magpies tend to be a little bit smaller than those of the Common Raven. Magpie landing traces also come with a long tail drag, as seen above - directly related to their long tails!

The one trace for which I've been searching for over a decade is a predatory avian trace. This would be the impression left by a bird, such as an owl, hawk, or corvid, attempting to catch a small mammal. Our predatory birds are still active hunters in the areas in which they winter, so if you have a wooded area, park, or cemetery* nearby, check out the ground for landing strikes by hungry birds. I may have two such traces I can show you in my next post in the Tracking the Wild in Your Neighborhood series. Stay tuned!

*Yes, cemeteries. Cemeteries are quiet areas, often near or within wooded sections. Cemeteries can sometimes be the few remotely "wild" areas in a densely populated area. They also have the benefit of not being subject to the regular foot and vehicle traffic of a city. Cemeteries can be calm oases for urban wildlife.

Wednesday, January 6, 2016

Tracking the Wild in Your Neighborhood, Part 1: Cat or Dog?

Happy New Year!

One of my New Year's science-themed resolutions is to be a more regular contributor to my own blog. I'm going to aim for a more regular, more frequent schedule of posts. This may mean the posts are shorter, but hopefully this will get me into the habit of both writing science-based communication regularly and writing about what I do on a more consistent basis.

I don't have an "off" setting for my ichnology-eye. Going on regular walks around town in winter highlights all of the great, accessible vertebrate neoichnology (studying tracks and traces of modern animals) that is right outside of our own doors. Most people think that tracking animals involves heading into rural or wilderness areas, and that the city (or small community, in my case) is devoid of regular wildlife. A walk around your own neighborhood can reveal a great deal about what animals (other than humans) frequent the area.

My favorite way to introduce people to the wonders of urban ichnology is with our favorite furry friends, dogs and cats. Both members of the Order Carnivora, our feline and canine companions have similar-looking (though not exactly the same) feet, and can leave similar-looking footprints. This usually comes up large carnivore footprints are found near an urban setting. Here's a Daily Mail article on some spectacularly bad reporting on large carnivore tracks (sorry). Local speculations run wild (pun totally intended). Is it simply the print of a large dog, or is it something more dangerous sounding, like a mountain lion? In the case of the above link, the critter in question is likely a large, running canine, and probably not the super wolf hybrid monster speculated at by the interviewees. It's reports like this, and more level-headed reporting on local large carnivore tracks, that can be the start of the question "How do we tell a dog footprint from a cat footprint?"

I conducted a fun poll on Twitter in December. I posted a carnivore footprint and asked "Cat or Dog?"

Here is the image I posted:
Cat or Dog?
Here are the poll results:

67% of responders were correct: this is indeed the footprint of a cat!  People responding to the poll used all sorts of great observational evidence to support their identification of Cat or Dog. Cat voters noted the lack of claws, the round toe pads, and the wide splay of the toes to distinguish the footprint from that of a dog. I was also a stinker and did I did not include a scale bar on purpose so that people didn't think large = dog, small = cat: I'm going to use the most technical terminology possible and say that size sucks thrice-used tea bags when it comes to identifying footprints. (Note: I don't think I'm going to get "sucks thrice-used tea bags" past peer-review any time soon.)

Those observations were correct. There are also a few other clues that can be used to distinguish Fluffy's footprint from Fido's footprint. Here's a quick infographic I constructed comparing cat footprints to dog footprints, using photos from my neighborhood (cat) and outside of my vet's office (dog).

Cat (left) and Dog (right) footprints, scaled to approximately the same size.

Identifying footprints of cats and dogs can be easily converted into an ichnology-based educational exercise. Cats and dogs are fairly easy for kids to connect with. They likely have one or both as household pets, or they regularly see cats and dogs around their neighborhood. Footprints of cats and dogs are relatively easy to find. Educators with their own cats and/or dogs can make plaster replicas of their furry friend's footprints to use as in-class examples. A cooperative companion animal (my cat would be the antithesis of cooperative) could be brought in to give live demonstrations of footprints in a sandbox, clay, mud, and snow to look at how footprint shapes change (or stay the same) under different conditions. Also, being able to properly identify a canine footprint from a large cat footprint can go a long ways towards looking critically at wildlife-panic reporting, as seen in the link above.

Stay tuned for the next Tracking the Wild in Your Neighborhood post: Birds of a Feather Make Snow Impressions Together!