Categories
Nature Observations Tumblr Repost

Eaters of the Dead

Bald Eagle photographed in Pinery Provincial Park, September 2021.

Here’s another repost from my old tumblr blog norfolknaturalist.tumblr.com. I’ve added some newer photos of the species involved but otherwise unchanged. Much of this article was inspired by my reading of the book Life Everlasting: The Animal Way of Death, by Bernd Heinrich. I thought the subject and title were appropriate for Halloween season.

Just as we were about to turn into my parents’ driveway last weekend (in April 2018), we saw probably the most iconic bird in North America less than 100 metres away from us down the road. A Bald Eagle (Haliaeetus leucocephalus) was dining on a Raccoon roadkill in clear sight. 

Perhaps it’s surprising that a bird of such noble renown was seen stooping to consuming carrion, something that we often see as repulsive. The truth is that the line between ‘predator’ and ‘scavenger’ is often a very blurred one. Most animals that eat other animals are willing to eat one that has already died or been killed. To the predator, it contains the same nutrients that it would obtain from its own kill but with much less effort (valuable time and energy) on their part. This isn’t to say that eating pre-killed remains is without risk for a predator or a scavenger. Besides the conflicts with other hunters over the resource, there is an omnipresent and invisible threat to all dead flesh.

Bacteria: organisms that are so tiny they are dwarfed by individual cells of our bodies. Despite being so small, and unseen without a powerful microscope, bacteria operate everywhere in the natural world and one of the most profound activities they perform is nutrient recycling and breakdown. While they disassemble cells and consume dead flesh, bacteria proliferate. Bacteria are the reason that predators can’t eat an animal body that’s been dead for too long. They are the reason dead things go “rotten” and become unpalatable by almost any animals. They are the unseen “competitor” with the visible and charismatic predators.

After at least an hour of feeding, and the frequent interruptions of cars passing, the eagle flew off and left the dead Raccoon. That is when the Turkey Vultures (Cathartes aura) moved in, creatures much more commonly associated with scavenging. And for good reason. Turkey Vultures have the most powerful sense of smell of any bird, and can detect a dead animal from over a mile away. What’s more, they can eat flesh that other creatures would turn down as too far gone. Their digestive system is able to break down the toxins of the ever-present bacteria, making them capable of consuming rotten flesh, where others cannot. 

It may be a grisly business, the consumption of the dead, but it is an essential (and amazing) part of ecosystems around the world.

Turkey Vulture photographed in Long Point, October 2021.

Categories
Nature Observations

Bullfrogs and Buffleheads

I usually like to discuss my nature observations soon after I make them, but that’s not always possible. In light of this, I’d like to describe some photos I took way back in March of this year. The week was rainy except for one day and I was determined to get out there and take some photos of birds, so I took a drive to Long Point and visited two marshy trails and was successful.

One of my main sightings on this trek were various ducks and geese. Ducks other than Mallards (Anas platyrhynchos) have the annoying habit of staying on the far side of whatever water body they are in, which means that I usually can’t take good pictures of them with my camera. On this excursion, I spied many of these groups of ducks keeping a wary distance and took many blurry photos of them. Most of these shy non-Mallards* were Ring-necked Ducks (Aythya collaris). One pair of ducks actually allowed me to get much closer and take decent pictures of them. These were Buffleheads (Bucephala albeola). By their extravagant head design, it was a pair of males. Buffleheads are related to mergansers and similarly dive for their food, which is mostly aquatic insects and snails (Baldassarre 2014). They make their nests in tree cavities (mainly those fashioned by Northern Flickers (Colaptes auratus)), and breed in the northern forests of North America wherever these woodpeckers are commonly nesting (Baldassarre 2014). The Buffleheads I spied floating across a Long Point marsh were either spending the winter here or moving back north to breeding habitats.

*for the record, I have nothing against Mallard Ducks and I usually end up taking pictures of them too (they are quite beautiful birds) but there is definitely a part of me that wants to see and encounter creatures that are new to me and Mallards are… well, they’re the most commonly encountered ducks in the world. I could use a very similar paragraph to explain my feelings toward Canada Geese (Branta canadensis).

Hanging out with the Buffleheads was another waterbird which I initially mistook for a female Bufflehead because of its close proximity to the males and lack of head adornment. A few minutes later the pair of males took off from the water and flew down the waterway in a flurry of black-and-white. Yet this other bird didn’t follow, instead making occasional dives beneath the water surface and popping back up again. When reviewing my photos it became clear that this bird wasn’t a Bufflehead, and it wasn’t even a Duck (member of the family Anatidae). My mystery bird was from an entirely different branch of the bird family tree, despite its superficially duck-like appearance. It was a Grebe (a member of the Family Podicepididae), specifically a Horned Grebe (Podiceps auritus).

Grebes swim in the water by means of their feet which like ducks are expanded to have more surface area but unlike a duck’s ‘webbed’ feet, grebe feet are said to be ‘lobed’. I have never seen a grebe foot before, because their feet are usually under the water while these superb swimmers float or dive. But take a look at this photo of a Horned Grebe and you will see why I mention the feet as they are very impressive.

Horned Grebe, with visible impressive feet, photo by Tomas Wuschke, used with permission.

The Horned Grebe I saw at Long Point was in its much less dramatic winter plumage (cross-reference the beautifully patterned adult in Tomas Wuschke’s photo above with the drab gray/black bird in my photo). They only very rarely breed in Ontario, and even then only at the very northern edge of the province, preferring northern Canada and Alaska where they create nests on floating vegetation in wetlands (Hughes 2001).

Muskrats (Ondatra zibethicus) were ubiquitous on both trails, frequently startling me with sudden splashes before scooting along at the surface or under the water. I observed a couple of these large rodents munching and was curious what they were eating but I was unable to tell from my photos. It could have been anything from vegetation to arthropods to fish since Muskrats are extreme generalists.

Two shockingly large birds flew in from the lake across the marsh, majestic and powerful eagles. Because of their large wingspan, I initially thought the birds to be Herons, which move south to avoid frozen water but will return once the ice has melted. Once I took some pictures I saw that the heads were definitely the heads of raptors, and I later figured out that they were juvenile Bald Eagles (Haliaeetus leucocephalus). 

While driving between the two trails I noticed a frog and did a double take. To notice a frog while driving says something about the frog’s size and indeed this was a representative of the largest frog species in North America: an American Bullfrog (Lithobates catesbeianus). This frog’s tympanum (the circular depression below and behind the eye) is much larger than its eye and its throat is yellow which indicates that this is a male, and males are generally smaller than females in this species! Bullfrogs can reach 20.3 cm (8 inches) long and will “eat nearly any animal they can capture and swallow” (Harding and Mifsud 2017).

The most noticeable resident on the second trail were the Killdeer (Charadrius vociferus), tearing about on their long legs and piercing the air with their high-pitched repeating calls. I love these birds and their distinctive cries, and seeing this many together at one time was a treat.

Before leaving each trail, I was able to photograph some small sparrows that were foraging along the paths. Watching these birds picking at the ground and presumably finding something to eat made me wonder what they could possibly be finding. A glance at the ground surface revealed no insects to me, but the Killdeer too were digging into the mud and finding plenty to eat. Watching birds forage like this always makes me marvel at the amount of life that must be present to sustain them, life that I couldn’t even see! There must be hundreds of tiny invertebrates that each bird was finding to sustain themselves. What an incredible invisible foundation to these flocks. 

American Tree Sparrow (Spizelloides arborea) photographed at the end of the second trail in Long Point.

References:

Baldassarre, Guy. 2014. Ducks, Geese and Swans of North America, 2 Vols. (revised and updated edition). Johns Hopkins University Press.

Harding, James H. and Mifsud, David A. 2017. Amphibians and Reptiles of the Great Lakes Region. University of Michigan Press.

Hughes, Janice M. 2001. The ROM Field Guide to Birds of Ontario. Royal Ontario Museum.

For related nature observations in Long Point, see:

A Green Heron Stalks the Shallows

A Visit to Big Creek, Part 1

-A Visit to Big Creek, Part 2