Naturespeak A naturalist's view of the world

December 26, 2009

Thief in the Night

Filed under: Uncategorized — wykes @ 7:06 pm

This is a small story with no end – at least not a satisfying one. It involves Luc, the captive bald eagle housed at the Lake Erie Marshlands Museum, his food, and a mystery guest. Luc is a good eater. Since this eagle is limited by his physical problems it is our job to make sure that he has enough food to meet his energy needs. This is especially important during the winter months.  Eagles are resilient winter birds. In the wild they perch in exposed locations, stand out on the open ice, and otherwise tough it out without the benefit of any shelter. Their thick coating of down acts as an insulating layer which retains body heat and buffers the effects of even the coldest of winds.

Wild eagles also have the ability to prime their engines by moving about over great distances. Luc gets in his calisthenics by engaging in short flights to and from his large perch – either to the ground and back or to his smaller perch and back.  He also shivers as a natural way to generate heat. All this requires energy. His diet, therefore, needs to be a hearty one -and it is. Depending on the day, he’ll get a heaping helping (about a pound) of fish, rabbits, or rats. Thanks to the generous donations of local hunters, he’s also had the recent opportunity to feast on venison and duck.

Not that we need to get into precise details here, but let’s just say that Luc leaves a lot of scraps after a meal. A rabbit is pretty well reduced down to a head, a gut pile, and a few unlucky feet. Everything but the head & backbone are consumed during a fish meal (the remains looking very much like those cartoon fish skeletons) while a rack ‘o venison ribs are picked clean to the bone. Rats are about the only eagle meal which produces no significant remains.

Sometime within the last month, however, we noticed that Luc appeared to be licking his plate (or his stump, as the case may be). There were very few pieces of any consequence left for us to pick up. I assumed he was eating more due to the colder weather and began to worry that maybe we weren’t keeping up with his appetite. The deer ribs remained in their picked state but they always ended up in an odd corner of the cage – tucked into the micro corner formed by the pond’s rock pile and the cage wall. Strangely, some of the few rabbit parts also found their way there. This complete consumption was very odd but the stashing thing was extra bizarre. Eagles don’t store food like squirrels – they eat them.

An old thought began to creep back into my head about this time. Early on, for several weeks after we received the bird as a matter of fact, none of us ever saw our eagle eat. He would not eat in front of people. Sure, the food would disappear by the next day, but there was always the nagging idea that some small mammalian creature was sneaking into the cage under the cover of darkness and making off with Luc’s food. Perhaps Luc was starving to death right in front of us as we kept piling mounds of food that he ultimately could never get a chance to eat!

After finally witnessing the eagle tear away at a freshly placed rabbit (a dead one, in case you are wondering) and noting the consistent meal remains, I finally felt comfortable that our eagle will grow fat and old under our care. Besides, the spacing between the enclosure slats was pretty small so it would have to be a pretty small invader. Then the weather turned cold and the previously reported events began to occur.

It took a few inches of snow cover to finally solve the first part of “the Case of the Moving Ribs.” In short, my earlier fears were real – a small mammalian invader was entering Luc’s cage at night and eating his food. That uninvited guest was an Opossum. His distinctive tracks pockmarked the snow around Luc’s feeding station (see track details above and below) and centered around a set of deer ribs pulled up to the tight inside corner by the pond rocks.

Opossum tracks are very diagnostic (see another view here). The front foot mark clearly shows a wide-spreading pattern of five toes. The impression of the hind foot is placed next to the front track and bears evidence of a thumb-like toe stuck out at a right angle from the foot pad. There was no doubt as to the identity of the maker of these marks.

The sneaky marsupial was entering the cage via the northwest corner where there is a slightly wider gap between the slats. A straight line of tracks led directly from the nearby marsh. Once inside, the beast was dragging the food scraps over to his dining corner (see here) and gnawing away in comfort before leaving by the same narrow door. Since opossums are nocturnal, they have nothing to fear from the likes of a diurnal bald eagle. Our invader was entering into the sleeping Cyclops’s lair and eating his sheep (Luc is blind in one eye).

It would be nice to report that we eventually nabbed the offending ‘possum and threw his lifeless carcass onto Luc’s feeding stump, but such is not the case – yet. This is the part where I must leave you with no true ending. The marsupial will have to go and the entry point will be sealed, but this deed will have to wait until I can secure a live trap and get the thing in hand.  I’m not in a terrible hurry.

Not all of my fears are realized in this scenario, for you see I believe the mammal is only picking at the remains and not eating all the bird’s food. Luc is getting his share and the lowly hair-beast is merely picking at crumbs. Perhaps over the Christmas holiday the opossum will overdo his gig and get fat. In that case he will render himself either too girthy to squeeze through the entrance point or, God forbid, too big to escape back to the marsh. In the latter case, the sunrise will prove fatal to our night thief as the enclosure guard awakes.

3 Comments »

  1. I’m surprised Luc hasn’t taken care of this unwanted guest himself! Our red-tail sometimes gets extra helpings when a chipmunk or squirrel enters her cage. The weasels, though, have yet to be snagged.

    Comment by Ellen — December 28, 2009 @ 12:56 pm

  2. Pablo:
    That boot print is mine! I stepped over to examine the tracks before leaning back and taking that picture. I decided to leave the boot mark in the photo, rather than crop it out, so as to provide some sense of scale. Luc’s cage is locked at all times, so the only human footprints in that cage are either mine or my co-workers.
    I am one of those humans that store things in corners, but I am running out of corners in my home cage. I’m considering moving to a round house.

    Comment by Gerry — December 28, 2009 @ 9:42 pm

  3. I know this isn’t a new blog, but I wanted to let you know that I was questioning whether I had possom tracks or raccoon, and I found your image through Google images. THANKS! You answered my question. Darn, s/he must be a BIG one, too…it looked like a toddler’s hand prints (overlapped with the foot prints) on my driveway this morning, and I was pretty sure there were no toddlers monkey-walking across my driveway last night!

    Comment by Sue Kent — January 26, 2011 @ 7:07 pm

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