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

Wind and walnuts

What: Finally got around to adding photos. Will post again on Friday. What a beautiful windstorm we had last Tuesday night. Of course this was easy to write from the comfort of my home, free of the flying debris and desiccating winds. Walking around the next morning there was so much debris that had blown down and I imagine that too early fall storms like this take its toll on plants and the still-developing fruits and nuts of things like apples, oaks, and walnuts. These windstorms are probably more helpful for deer and turkey that can't climb trees to get access to apples. The red squirrels (Tamiasciurus hudsonicus; "tamias" means hoarder) seemed extra pissy about it. In about 5 minutes I had collected a 5-gallon bucket's worth of walnuts, that's 5-gallons worth of walnuts the alpha red squirrel could no longer defend from the gray squirrels and beta red squirrel. In the last week since the wind knocked the walnuts down, the red squirrel has seemed less insistent about waking up at dawn to claim his territory, as though the wind was blown from his sails.

Ecological notes: We usually get these gusty Fall storms later on in the season, typically in November. Most of the debris on the ground is likely a result of all the leaves still on the trees, which catch the wind and want to be carried away. By November the leaves have fallen and the wind has a much less dramatic effect on the trees.

A uninfected husk (left) and one hosting a healthy colony of husk fly (right).

Black walnuts (Juglans nigra) have a thick outer husk that's filled with juglone (the same allelopath - toxic chemical - found in the roots that hinders the growth of other species). The chemical stains your hands (and can dye fabrics anything from an earthy yellow to a deep green); it also stains the mouths of squirrels this time of year. The walnut husks that have black on the outside have been colonized by a fly whose larvae eat the husk but leave the nut in tact. I cracked the one below open and found one larvae and two pupae (the shiny dark brown cylinders in the photo to the right).

 

Gladys eating the walnut husk fly maggots (Rhagoletis sp.)

The shell of the walnut is super tough and sharp (apparently used as an industrial abrasive). It's got a complex labyrinth of groves and channels that the nut fits into, making it difficult to get out large chunks of the "meat" (see photo at top). So it's a lot of work to get at the meat, but if you have lots of time, well worth the patience as it's delicious! It has a sweet minty flavor to it.

Where: All over Vermont

Other notes: Callan and I drove back from Fairfax last Tuesday night. Before we left we heard spring peepers (Pseudacris crucifer, formerly Hyla crucifera) calling. The roads were filled with frogs crossing back and forth. When I got home I was greeted by a chorus of gray treefrogs (Hyla versicolor). The wet weather has brought the young amphibians out in droves. At the fall equinox, the ratio of light to dark during a day is the same as it is during the spring equinox (March 21), which is roughly the time that amphibians first start singing. One theory is that the fall chorus of frogs is from confused young males that are cuing in to daylength.

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.