The Continuing Saga of Squirrels and Walnuts

*** Starting this week my UVM students will be posting occasionally in response to the prompt: Find something in the woods that you've never seen before and figure out what its story is. So look for that!

What: Last week Clay and I found a dead gray squirrel (Sciurus carolinensis) on the sidewalk. It was a pretty good mystery as to how the squirrel had died. I skinned it with my Crow's Path kids and before we did the autopsy we couldn't detect any broken bones from getting hit by a car (plus it was about 10' from the road). The squirrel was a full grown male (just about the most enormous squirrel I've seen), and we thought maybe it could have eaten poison from a nearby house, fallen out of a tree, got hit by a bike or chomped by a cat/dog. We couldn't find any evidence of blunt trauma from getting hit by something, but when we pulled the skin up above the neck we could finally see two chomp marks that hadn't pierced the skin (so no external blood) but were most likely what killed this little critter.

You can notice in the two photos below the difference between the rear (left) and the front feet (right). The difference in color is due to the constant assault of the squirrels on the walnuts (see my previous post on how it stains their face and paws). I love looking up close at squirrels to see all the little differences between individuals, and this little guy, with a lone black chin hair popping out, was no exception. It also had orange staining its whole belly, probably from eating walnuts and then grooming its belly (around its crotch was particularly orange, which was amusing).

Ecological notes: With the kids we noted that the rear foot was flexible in almost all directions and could rotate just about 180 degrees. I was telling the kids that the squirrels will hanging from a tree hanging down with their feet rotated back behind them. I've also noticed that when they leap to a branch they rotate their feet so that they're hanging below their body and the bottoms are facing the direction they're going. As they hit the branch their rotated feet catch their body and grip onto the branch as they then rotate around to face forward and propel them in their next jump. Amazing! Another thing to note is that animals have larger feet where they hold most of their weight. Gray squirrels hold most their weight in their butts, so have larger rear feet. Same with raccoons, possums, beavers, etc. Dogs (think about pitbulls here) have larger front feet to support their broad chests and big torsos.

Where: Burlington

Feet & all those dead squirrels

What: I was driving home from Sterling College last night and I hit a young male red squirrel (Tamiasciurus hudsonicus). I felt terrible, but at least it died immediately. I scooped it up and brought it to my CCV Natural History course today to skin with my students. It was neat to be able to see the paw prints up close, to be able to see the palm pads in such detail. All rodents (even beavers, muskrats, mice, voles, capybaras) have five toes in the rear and four in the front. Red squirrels spend a lot more time on the ground relative to grays (Sciurus carolinensis). On the ground, the front feet of reds tend to be offset far more than grays. Think about an animal who spend all that time "perched" on a branch with its feet side by side - when it runs along the ground its front feet keep that side-by-side pattern as seen below.

Red Squirrel                  Gray Squirrel
(ground dwelling)         (tree dwelling)
 H     H          H      H       /\
     f              f  f         ||  H = hind
   f                             ||  f = front

This of course is a tendency and not always true. So in general animals that spend more time on the ground tend to follow the pattern or red squirrels, with front feet landing offset, and animals that spend more time in trees, like gray squirrels, land with feet side-by-side. One of the things reds are doing with all that time spent on the ground is harvesting mushrooms. Look in a stand of hemlocks for mushrooms lodged in the crotch of a branch, left out by red squirrels to dry for a winter supply.

Rear feet, five toes, long flat foot

Front foot, 4 toes, smaller dexterous digits

Ecological notes: Red squirrels spend this time of year in search of a territory to defend over the winter, when food resources are drastically reduced. Fall dispersal of yearlings is always a rough time for animals, with lots and lots more road kill this time of  year than at others. Below are the feet I got from a raccoon (Procyon lotor) that was road kill just north of Stowe. I surprised at how much fat was stored up in the tail.

Raccoon feet (rear feet on outside, front on inside)

Where: North Wolcott along the Wild Branch

The Diversity of Squirrels (in my backyard)

Notch-o on my roof

What: After my last post I decided I wanted to really get a handle of who is who in my backyard. It's pretty obvious who Captain Death is, since he has but one ear, but there are about 4 other gray squirrels that also use my yard at various points throughout the day. Another one has a large cyst like thing on its left side, making it another easy one to ID. The lady above has a pair of notches on her ears, presumable from a male biting them during their odd little courtship routine.

A while back I thought it would be a fun challenge to see how many wild animals I could touch. It becomes pretty obvious pretty quick that the easiest way to win an animal over is through its stomach, whether it's downy woodpeckers, woodchucks, beavers, or chickadees. So in the spirit of feeding wild animals and in order to get a better handle on the rascally little squirrels I set up a feeder in the middle of my yard. This way I can see them out in the open and watch them long enough to start to discern unique features that will allow me to recognize each individual (gender, size, coloration, scars, tail length, etc.). Next step will be to name them.

FIELD GUIDE TO THE SQUIRRELS OF 56 LATHAM CT:
1. Squirrel has one ear: Captain Death
1b. Squirrel has two ears
      2a. Has large cyst (or whatever it is) on left side: Lumplestiltskin
      2b. Does not have cyst on left side
            3a. Both ears notched: Notch-o
            3b. Both ears not notched
                  4a. One ear notched (has scraggly tufts on back): Tufts
                  4b. No notches in ear: Youngyun

Tufts

Tufts, showing those clumps of scraggly fur on back

Youngyun with a walnut I set out for her

Youngyun with feet extended backwards (grays can rotate rear feet 180o)

Where: My backyard (but could just as easily be yours)

Other notes: I've noticed that their mouths all seem to be a bit darker these days, probably from the non-stop chewing of walnut husk. My hands are stained for a couple of weeks after handling walnuts, and I imagine it sticks just as well to fur as to skin.

Captain Death

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What: In college I started Ye Olde Lovable Li'l Scamps Feeding Clubbe (Y'olls FC). We collected stale bread from the dining halls and spent lunch hour on the quads hand feeding the squirrels. After a few days we could easily recognize one squirrel from the other by personality as well as by physical scars on each animal (more than not had some sort of visible scar on its face). It turns out squirrels lead a pretty tough life. One in particular, who we called Captain Death, had a large scar cutting diagonally down across his face. He was certainly the most skittish, but once we earned his trust he was the one that would approach first and stay the longest. Each time a new person joined us, Captain Death had to be won over again.

Many of the females had ragged ears or other signs of the hazards of living. Males with aggressively court females and defend access to them (see my post from May 7 for more on that). I assume that many of the scars on the squirrels were from squirrel-to-squirrel interactions during breeding season. Once we had the chance of watching a red-tailed hawk swoop down and steal a squirrel off the ground. The hawk was successful and we then watched it eat the squirrel. I imagine that not every attempt ends this way and that many a squirrel lives to climb another tree, hide another acorn, a scar as wide as a talon bears witness to the fact that squirrels are prey.

Well this morning my mom, Callan, and my sister were outside when they spotted this sad little earless squirrel. He was happily (well, as happily as he could have been) cleaning the husk from a walnut from the shell. I've been finding walnuts hidden everywhere around my backyard. The gash runs from his eye (barely visible in some of the photos) back towards his left ear (you can easily tell it's a male in the photo below), which is noticeably absent. The wound looks fresh and I haven't seen this scar before so I'm assuming it happened in the last couple of days (there's no blood on the fur, so it at least had a chance to clean that off).

Ecological notes: The squirrel was eating a walnut from our tree. This has definitely been a bumper year for walnuts and a red squirrel (Tamiasciurus hudsonicus) has been fiercely defending it, trying in vain to fend off the grays from stealing a snack.

Where: We spotted the squirrel on one of the wonders of the modern world of Latham Ct (the Silver Maple in my driveway).

Mourning doves

What: We've got a pair of mourning doves (Zenaida macroura) that started to build a nest in a boxelder (Acer negundo) at the end of our street. I watched the male bring supplies to the female all morning. It was a hot and listless day and the female was yawny waiting for the male to return with sticks (for more on how to identify male vs. female, check out: The Secret Life of the Mourning Dove by Michele Patenaude; in short males are larger, have rosier chests, and have more irridescent heads).

As is evident in the video, it appeared as though the male was testing the strength of each twig/pine needle to be added to the nest by banging it against the ground. Flimsy ones were discarded, sturdier ones brought back. It was fun to watch him pick through the bounty of needles and twigs in search of the perfect ones. I was in and out all morning, but I'm pretty sure the male worked on this for about 6 or 7 hours before my sister and I left the house. By the following afternoon it was abandoned for whatever reason.

A finished mourning dove nest is kind of a disaster so it was hard to tell that it had even been abandoned. I found one a few years ago with Ian Worley and I asked if it was old because it looked like it was in awful shape. He said that was par for the course and the active nests I've seen since then look almost like the birds don't really care at all for craftsmanship or aesthetics. But I guess if you're building a nest in a scraggly tree like a boxelder you build a scraggly looking nest to blend in.

Ecological notes: The nest went unfinished and I think they selected a nearby site over the next couple of days after the video. Last Sunday, Brian was outside and watched the doves attacking a red squirrel. I went out and the red squirrel was coming down a white pine with feathers clinging awkwardly to its mouth. At least one of the mourning doves, and I can't really think of a more docile bird, were going crazy. So the video is from July 1st, 7 days before "the attack". I suspect that they rebuilt and soon after laid eggs. I don't know that the eggs had hatched yet, but my guess is that the doves defended their nest from the red squirrel and the red squirrel might have bit back, but not been actively hunting the doves.

Where: Burlington, VT in my backyard.

Other notes: The red squirrels have been extra bellicose the past couple weeks. It's amazing, I hadn't really seen any of them in my back yard for about two months - just an occasional sighting. But now that the fruits on our black walnut (Juglans cinerea) are swelling, they've been fighting off the gray squirrels like that's the last food source on earth. They start wailing at dawn and don't really stop. What's interesting is that the gray squirrels, though they are certainly submissive, have been equally vocal.

Also, there was a robber fly in my backyard today. I couldn't tell what kind it was nor could I tell what it was eating, but it was fun to watch it devour its meal in fits and starts.

Adventures with gray squirrels

What: My neighbor has a squirrel problem that I was happy to help with. She replaced the insulation on her chimney a couple weeks ago and thought that she had taken care of the problem, but apparently she was mistaken. On Friday I helped her chase out one of the squirrels. It turns out there were three more (much much smaller) gray squirrels still in the basement. I sealed a hole in the chimney, and coerced a couple into boxes then relocated them outside. The last young one definitely proved the most difficult. We set a havahart and baited with peanut butter, to no avail. Saturday morning a friend and I went into the basement and tried to catch the squirrel. It cornered itself in a stack of winter tires. It was growling pretty fiercely, but we managed to wrap the tire in a cover for the grill and then carry the whole thing outside. The video is the Great Releasing of the Squirrel. It was pretty much spring loaded and disappeared off along the fence line in a few short seconds.

Ecological notes: I had noticed the gray squirrels in my yard being a bit extra frisky in mid-February during some of the warmer weather. They breed twice a year so I assumed that this was breeding behavior. Their breeding affairs are a rather violent and complicated matter. Females often have scarred ears and necks from the males biting them during copulation. As females are only in estrus for a single day, promiscuity is the rule (a less charged word might be polygyny - many males mating with a single female). Ecologists like John Koprowski (who wrote some awesome stuff on squirrel mating behavior in the early 90s), suggest that females can be seen as a limited resource and are therefore highly prized and fiercely defended (like the black walnut in my backyard come September). A dominant male will thusly defend a female (or at least access to her) during the breeding season. Part of this is behavioral male-to-male aggression. But part is physiological.

During copulation the male will ejaculate and then secrete a gelatinous substance that hardens into a plug. The male has to then fend off other males until the secretion hardens (about 20 minutes), which effectively blocks another male's sperm (gross, right?). I would assume that the reason males have such gargantuan testicles during breeding season is to have such powerful blasts of semen as to break through other male's copulation plugs (aka mating plug, sperm plug, vaginal plug, or sphragis).

If the adult in Laura's basement had been an adult then she would have mated in that mid-February warm spell, gestated for a month and a half, then given birth to little naked helpless pups in the beginning of April. It'll be less than two more months before they're fully weened and ready to tackle the world. This would put them out on their own by about June 1st, so it's not unlikely that the group of four was a mother and her three pups.

Where: Latham Ct