mammals – Page 14

Recent news: Doe with antler

We get two local papers here, the Frontenac News and the Frontenac Gazette. An interesting thing about rural and small communities that you don’t really get in larger cities is these community papers. Of course, the larger cities have their own papers, too, they’re just serving more people so they lose that intimacy, that sense of community. Instead of hearing about local birthday parties or shop owners, or the front page photo being about the Superhero Spirit Day at the local high school, you’re hearing about various crimes and politics and the financial market. It’s much more interesting to read the little community papers.

Even so, I don’t always read them all, so when I was crumpling up a sheet from the News to get the fire started a couple mornings ago an article I hadn’t seen caught my eye, mostly because of the photo, which was of a deer. The headline read, “Local hunters fell unusual catch”. The full article is in the image above, but the gist of it was these hunters had killed a deer that had a single antler, which was in velvet. The deer, it turned out, was a female, a doe. A story about a female deer sporting an antler, won’t see that in the Toronto papers.

The story notes that the hunters called the Ministry of Natural Resources “with two understandable queries: 1. Is this a safe animal to eat? and 2. Would the MNR be interested in it?”

Those weren’t the questions that I was expecting. The two that had sprung immediately to my mind were: 1. Why does this occur? and 2. How common is it? The latter question had been answered in the article (although the hunters hadn’t known that upon killing the doe, I don’t think) based, I gather, on the MNR’s website. But the first question is not touched upon in the story. Really, that’s the most interesting part about it all, in my opinion.

So to finish off the story, why does this occur? And how common is it? Sources disagree on the answer to the latter question, with Wikipedia saying 1 in 10,000 will have one or both antlers, an article from Penn State U suggests 1 in 1,000, the Minnesota Department of Natural Resources suggests that it can vary from one population to the next, usually between 1 in 1,000 to 6,000. The same page also mentions one study in Pennsylvania found the occurrence to be 1 doe in 3,500 antlered deer (so, 3,499 males and one female), and another in Alberta counted 8 antlered does in 517 does total (about 1 in 64, thought to be the result of unusual genetics in the area, or perhaps just a sampling bias).

The explanation of why this happens lies in the physiology of the antler itself. It all begins with testosterone, the hormone produced primarily by the male testes, but which is also found in females (usually at about 1/20th the concentration it is in males). Deer have bony “buttons”, called pedicels, on the frontal bones of their skull. In the spring, a surge of testosterone triggered by increasing daylight levels prompts the pedicels to start developing bony growths. Initially they are soft, covered in blood vessels, nerves and fuzzy skin, referred to as velvet. In late summer a second surge of testosterone causes the bone to harden, the blood vessels to die back, and the velvet to slough off. The male deer rub their antlers against trees and branches to “polish” them, and remove the velvet, and then they use these hardened growths to spar with each other during the rutting season in fall. Early in winter, in the weeks surrounding Christmastime, the testosterone levels start to subside, and a layer forms between the antler and pedicel. Eventually the layer loosens enough that the antler is rubbed off and dropped. In the spring the cycle begins again.

In the case of these unusual does, some trigger such as a hormonal imbalance caused by first pregnancy, tumours, or degeneration or malformation of the reproductive organs or adrenal glands, releases that surge of testosterone that prompts the pedicels to start forming the soft velvet antlers. However, the doe never receives that second surge that results in the velvet sloughing off, or the subsiding of the hormone from this high level that causes the antler to fall off, so she ends up carrying a permanent velvet antler(s). Many such does are reproductively functional and can and do bear young, though others may have malformed reproductive organs. Some of these “does” may actually be hermaphrodites with the female organs dominant, or gyandromorphs (one half of the animal has XY chromosomes, the other XX – that is, one half is male, the other female, sometimes split nice and evenly down the middle like this Rose-breasted Grosbeak). “Does” with polished antlers, where the velvet has fallen off, are more likely hermaphrodites with the male parts emphasized, cryptorchids (males with undescended testicles, “crypto” is Greek for hidden, and “orchid” Greek for testicle), or pseudohermaphrodites that externally resemble females but internally are male.

So there you go, the rest of the story that was left out of the article (I figure they must have just run out of room on the page…).

Do-it-yourself home-building

The other animal that was in plentiful evidence during the hike was beaver (Castor canadensis). Dan actually saw one at the first pond we stopped at, toting a freshly-cut stick, but I missed it and that was the only individual observed. However, it was clear that beavers were not in short supply in the park. Virtually every one of the smaller water bodies we came across was the work of a beaver. And we came across a lot of small water bodies. I started taking photos of each dam as we found one, and I have photos of five total. The above photo is beaver pond #6, the very first pond we came across, and the one where Dan spotted the beaver. We came across it mid-pond, and I didn’t notice the dam itself there; I suspect it was at the far end, the end we didn’t walk around.

However, you don’t need to find the dam to know that the pond is beaver-made. Beavers live in two main types of habitats: large lakes that are pre-existing, where they build themselves a lodge but don’t need to go to all the work of making a dam, and in small beaver ponds that are of their own creation. We have a few beavers of the former sort living along the shores of Kingsford and Birch Lakes. The latter may be offspring that live with their mother and then inherit her dam and lodge when she dies, or ones that scout out a new site along the river. They’ll pick a spot along the river that looks promising, usually a narrower spot where it’s easy to bridge with a dam, and then get to work. The end result is that as the water in the river backs up behind the dam, the river basin or valley floods and the water rises into the surrounding forest and drowns the trees. In young beaver ponds these trees may be dead but still standing; in older ones most will have fallen and all that remains are the weathered stumps. Also, as in here and below, the slopes surrounding the water’s edge have been cleared of trees, looking a bit like a strange clearcut.

In areas where the landscape is relatively flat and the river basins shallow, the beaver ponds end up being wide and flat, and usually not very deep. We didn’t see many of those. The landscape here in the semi-Shield of the Frontenac Axis is very steep and rugged, and river valleys tend to be deep and steep-sided. In flat landscapes the beaver pond may simply look like a pond, but it’s often easy to tell that the ones here in the park used to be creeks, as they follow the contours of the steep-sided river valley.

This is a very old dam, as evidenced by the grassy cover that graces its top. It almost looks like a deliberate, grown-over footbridge. Beavers often live in colonies, and although an individual beaver may live for 4-5 years (or as many as 15 for a lucky soul, though they can reach 23 in the protection of captivity), the dams and lodges can last a few decades as they’re “handed down” from one generation to the next. Beavers are meticulous in the care of their dam, plugging holes quickly to maintain its structural integrity, and regularly reinforcing it with new sticks.

Dam #2, also covered in grass, on the left of the photo. This beaver pond still has a lot of old wood standing in the water. Beavers build dams and create ponds for the primary purpose of protection from predators. Ideally the resulting pond should be deep enough that the bottom doesn’t freeze in winter, and that allows the beaver to swim and dive for safety. In ponds like this their lodge is usually a separate structure, in the centre of the pond surrounded by water (lake-dwelling beavers build their lodge on the shore, since the centre of the lake is too deep for a lodge). In the summer the “moat” protects the dwelling from potential predators. The entrances to the lodge are underwater, and the top is packed with mud which, when dry and frozen in the winter, form a nearly impervious barrier to the claws or jaws of predators that might cross the ice and try to break in. The pond also makes it easier for the beaver to tote branches from one area to another, for instance to mend the dam, since floating it on the surface provides much less resistance than dragging it across the ground. Finally, the pond provides food, growing the water lilies and other aquatic plants the beavers like to eat in the summer.

Dam #3, less grass on this one. Note the fallen tree in the foreground. Once the beaver has picked a spot to locate its dam, it usually begins by felling a tree that is strategically located close to the river, such that when it comes down it helps to form the foundation of the dam-to-be. In the case of this one, its crown and branches would’ve created a great framework into which the beaver could fit the rest of the sticks and logs it brought over. It takes a pair of beavers only three or four days to build an average dam solid enough to begin retaining water.

Although most dams are probably no more than a few meters or yards wide, in shallow landscapes beaver dams can become incredibly long as the waters spread out and the beavers build it wider to retain more water. The record-holder was found in Saskatchewan, and was 1,500 m (5,000 feet) long and 3 m (10 ft) high. The largest one currently in existence is 850 m (2790 ft), found on Google Earth in northern Alberta, and has been there for some 15 years. Another long one of 652 m (2,140 ft) exists near Three Forks, Montana. Dams across weak streams tend to be relatively straight, but ones built in stronger flows are usually curved into the direction of flow, to brace against the weight of the water pushing against it.

I didn’t see the dam for this pond, but I did spot the lodge out in the middle of the water. A typical lodge is about 2 m (6.6 ft) high above the water, and 4-8 m (13-26 ft) wide at the water’s surface, but extends some distance under the water as well. It’s built so that the entrances to the inside chambers are accessible only from underwater. The beaver swims in the entrance into a preliminary chamber where they climb out of the water and allow themselves to dry off a bit, before continuing on to the main chambers. This helps to keep the main chambers drier, particularly in winter when things don’t dry out as quickly. Interestingly, beavers construct their lodge in a very similar manner to how we’d build a quinzhee, by creating a large pile of sticks and then “hollowing” out the living chambers, leaving a few branches in place for roof support. Beavers are nocturnal, so they spend much of their day snoozing in their lodge, probably the other reason we didn’t see many while we were out hiking.

That’s all from Friday’s hike; although there were more pictures and things to share, it’s time to move on to other topics. Tomorrow: deer in the news.

Other things in the woods

I probably ran off a good 150 photos while out with Dan and Raven at the park the other day. I would likely have taken more but for the fact that we were running out of time (constrained by the number of hours of daylight) and I eventually had to exercise some restraint in not stooping down to photograph something every 20 meters. Also in that we didn’t find the bog; if we had, that would’ve been another 50 photos just in itself. I’m beginning to run out of disk space on my computer, and it’s not a particularly small hard drive. That’s what a 10.1 megapixel camera does for you. I should start printing some of my photos up and selling them as posters, to take advantage of those 10.1 megapixels (since there isn’t much other need for them). I wonder if they’d actually sell.

I take lots of them with the intention of sharing their subject matter here on the blog. Of course, often they get buried as I turn to more interesting or more timely subjects and I never come back to them. But other photos are just simply landscape images that I found really eyecatching or said something to me. Many of these sit dormant, buried in the hard drive somewhere. Some I share here. The above (obviously) falls into the latter category. So many of the water bodies we encountered were reflecting the sky in the most gorgeous, rich, deep sapphire blues. I really couldn’t capture it with the camera, at least not the way my eye saw it and not without any fancy filters or equipment. But I thought this one came close.

We came across this snake on the path. It’s an Eastern Ribbon Snake, Thamnophis sauritus, and can be separated from the similar-looking garter snake by the presence of an additional yellow line along the side (that is, the garter snake has a yellow dorsal line and a yellow belly, while the ribbon snake has a yellow dorsal line, a yellow side line, and a yellow belly). It’s also a slimmer, more delicate-looking snake. I actually nearly stepped on it, only noticed it as it rapidly slithered out of my way into the leaves at the side of the trail. I called to Dan to point it out, and he managed to snag it for a photo. It was fierce, and actually struck out a couple times toward the camera (seemed to pay no attention to Dan, interestingly). It also stunk like a sonuvagun. Most snakes produce a very smelly musk from glands in their vent (the combined reproduction and elimination orifice that reptiles, amphibians and birds all have) that serves to discourage predators. Sure discouraged us, more than the open mouth. Dan put it down quickly once the photo was taken.

Not much further along was this Common Garter Snake, Thamnophis sirtalis. I was rather surprised to encounter one snake on the trail, much less two, given the lateness of the season. However, the weather was nice, nearly 15 C (60 F) and they probably came out for some last filling up before hibernating for the winter. They were sunbathing on the warm leaves when we came across them, and while the ribbon snake scurried off, the garter snake didn’t move at all. Garter and ribbon snakes are closely related, members of the same genus. They’re among the most common snakes, found in suburban gardens and yards as well as the untamed wilds of rural areas.

Aside from the two snakes, and a handful of chickadees, Brown Creepers, and a couple other birds, not very many animals were observed. However, they were in evidence from the signs they left behind. This birch stump was at the side of the trail, and looked like it had been freshly worked on within the last couple days. It’s the handiwork (billiwork?) of a Pileated Woodpecker looking for ants or grubs. The size of the excavation, plus the neatness of the edges, identify the species responsible, since other woodpeckers will make smaller excavations without much mess, and larger animals, such as raccoons, will make messier holes. I thought it was neat how the shards of wood cascaded down from the excavation like a waterfall spreading out into a pool at the base of the stump.

Another animal that had left some signs of its presence behind was White-tailed Deer, Odocoileus virginianus. We found a few spots with droppings, but also quite a number of these scrapings in the ground. The leaves had been cleared away from the area as the deer looked for things to eat, and the primary reason I knew it was deer and not something else was the presence of the cleft-hoof tracks in the dirt. Deer are known to eat acorns and beechnuts as part of their fall and winter diet, and since the predominant trees in the area were maple, oak and beech, these were abundant in this forest. I suspect they were clearing the leaves in search of acorns, now that most plants have lost their green vegetation.

And finally, on our way back, as we crossed through a grove of pine trees, we came across a large area of ground that had been dug up as the animal searched for food. In a couple spots, in the middle of the excavation, were some piles of loose gray scat. It’s amazing how much you can tell from scat. It’s often very species-specific in its particular characteristics. In the photo above Dan is poking at it with a stick to examine its consistency and contents, both important in determining from what animal the scat came from. There aren’t too many species that will actually dig up the earth like this, as opposed to just scrape at the surface like the deer did. Two of the possible critters, skunk and raccoon, have tight, compact scat. The other suspect tends to have looser dung, as this was, and a varied diet. This looked like it was full of crushed mussel shells (though we didn’t look too too closely to know definitively). After examining the evidence, we thought this was probably the work of a Black Bear, Ursus americanus. Bears are omnivores, eating a wide variety of foods, from berries, to grubs in the soil, to mussels at the lake shore.

So many things to see! One more post tomorrow from that hike, and then on to other things.

The Dark is Rising – or is it?

The full moon is Thursday this week. They’re forecasting overcast skies and precipitation for the next several days, so I’m not sure we’ll see it at its peak, but right now, two days before full, the moon is pretty bright, enough that we don’t need to wear a headlamp to walk down to check the owl nets. Moonrise this evening was timed with dusk, and as I was looking out over the lake an hour or two after the sun had gone down, the rising moon caught my eye, hanging behind the silhouettes of the tall trees in the yard. I grabbed my camera and set it up on a tripod out on the deck. Uncertain about what exposure was necessary to capture the scene, I took several at different settings. The above was the one that most closely resembled what my eye saw. All the photos were taken at F/5.6 and ISO800, with just the shutter speed changed – this was at 1 second exposure.

Some animals can see a lot better in the dark than we can. This is largely due to the structure of the eye. The vertebrate eye contains two types of cells in the retina – rods and cones. Rods are used in capturing light, and cones are used in detecting colour. Humans have more cones than rods, which is why our colour perception is so good. We have some rods, but being primarily diurnal species we don’t need a whole lot. Other critters, on the other hand, who do a lot of moving around at night tend to have more rods than cones – colour isn’t as important at night. Cats, for instance, frequently hunt at night and are known for their excellent night vision. The average cat has about six times more rods in their retina than a human (which translates to about six times more light captured, allowing them to see about six times better). I fancy that this is what the world looks like to a cat at night. This was a 4 second exposure, so not quite six times difference, but close.

Owls are well-adapted to hunt at night, and may have among the best night vision of any land creature. Their retinas have as many as 10 times the number of rods that those of humans do, so they can see exceptionally well in the dark (this is helped by their exceptional 3-dimensional hearing, which results from their ears being off-centre from each other). Owls also have very large eyes relative to the size of their head – so large, in fact, that there’s hardly any room for eyeball muscles to move them around, and so the eyes are fixed in the skull. To look around the owl moves its whole head, and although it doesn’t have a complete 360 degree range of motion, it does come fairly close. These large eyes provide a greater expanse of retina for light collection, also contributing to their excellent night vision. This was a 15 second exposure. It might as well be daytime, you can even make out the colours of the trees across the lake.

In doing some of these long-exposure photos I often find it astounding how much light is actually available to the camera that our eye just can’t detect. It may look like the dark is rising at sunset, but it really isn’t.

Today not at Kingsford – Riverside living

My parents’ new home sits next to this beautiful river. I don’t just mean it runs nearby along the edge of the property. I mean the house sits next to the river, separated only by the garden and driveway. From the kitchen window you can look down into the river, see what’s visiting today. It’s not a small river, either, probably a good 30-40 feet (10-13 m) across in most spots. The water is still a little murky to really get a feel of how deep it is, but it is clearing up; back in September, when I saw it the first time, the water was very cloudy with silt, erosion, I presume, as a result of all the rain we had this summer.

The wildlife finds the river appealing, as well. There are beavers who have built a lodge in the river along the section that abuts my parents’ land. My dad and sister have apparently seen the residents, but neither my mom nor I have. I had hoped to get a photo of them this week. We have beavers resident on Kingsford, too, but you can’t get nearly this close to them. There’s also been Wood Ducks staging on the river, sometimes as many as 15 together in a flock. I hope that means that some will breed in the forest next spring, although the forest may still be a tad young, it’s hard to say. And Great Blue Herons wade along the shore. I don’t know if there’s fish in the creek, since it’s hard to see into the water, but if not they could just as easily be stalking frogs. My mom has also seen the herons at the small manmade pond on the property, and while I have actually seen little fingerling fish in there, it’s more likely that the frogs are their main interest there.

There’s something about water that lends so much life to a piece of land. Their property would be really nice just on its own, but having this river coursing along the length of the property’s northern edge makes it really nice.