Naturespeak A naturalist's view of the world

April 22, 2009

Big Rusty Birds

Filed under: Uncategorized — wykes @ 9:27 pm

Standing 4-5 feet tall, and weighing in at 9 1/2- 12 pounds, Sandhill Cranes are Michigan’s largest bird. They are hard to ignore even when viewed from a great distance. They simply command attention when seen in close vicinity.  I was so commanded when I came across a pair of these stately birds at Kensington Metropark last week.  High atop a grassy knoll by the park office, the cranes were preening as I pulled up. Neither my presence nor the scattered downpours disturbed their concentration.

Sandhills, like all birds, spend a lot of time preening their feathers. Wild birds don’t usually engage in such behavior, however,  until they feel comfortable with their present surroundings – after all, bending over backwards and picking away at armpit dingleberries tends to detract from predator alertness. Perceiving that I was not a threat, my two Kensington birds went about their daily duty with a zen-like determination.  You can pick up on a few rules of feather care as you watch their antics (see here a movie of a preener in action ) .

Preening is all about keeping feathers tidy and oiled. A long beak and neck certainly makes things easier, but all birds are endowed with the proper anatomy to get the job done. The length of each feather is individually pulled through the open beak in order to literally zip it together – insuring that the barbels remain interlocked. You can see this “zipping” especially well when the long flight feathers are given the treatment.  Another regular part of the routine involves reaching back to tweak the oil gland located on the rump (see here). In this case, the bird drops his wings to expose the gland and pinches it between the tips of the bill. The exuded waterproofing fluid is then spread over the body feathers.

In a normal sequence, the procedure begins with the back – between the scapulars or shoulder feathers – then to the wing coverts, lower neck and breast.  The wings are extended to get at the “pit” feathers. When two preening birds stand side by side, each at a different stage of the process, the sight offers the appearance of a modern dance statue (see above).

A Tai Chi stretching session (see below) marked the end of the procedure and insured the prospect of proper balance and inner avian peace. Each bird eventually leaned forward, while balancing on one leg and holding both wings out at full spread, and proceeded to hold its other leg straight out. This ultimate stretch-out ended the whole affair. In all, the preening lasted about 15 minutes.

After all this preening stuff, you’d think that these Sandhill Cranes would be cleaner but they were, in fact, dirtier!  When cranes feed, they probe the ground with their bills (see here). They are omnivores which feed on small mammals and  invertebrates, but they spend most of their time pulling up plants. While doing so, they get quite a bit of mud on their bills and they make no effort to clean it off.  Sandhills deliberately rub this iron-rich mud into their feathers when preening and thus turn their normally gray plumage into a rich cinnamon brown shade. Since they can’t reach their own face or neck, these parts of the plumage remain pristinely gray and white.

The secondary purpose of preening, therefore,  is to stain their feathers with rusty soil. Some believe this behavior imparts a bit of camophlage which protects these birds when attending their nests and young, but this is not at all certain. Hey, maybe they like to get dirty!

Sandhill Cranes are known for their loud raucous calling and dancing – which, considering this discussion could be called dirty dancing. Their distinctive rattling “gar-oo -oo” carries a long way over the landscape. I was privy, however, to a lesser known species call as the pair ambled close to the car and crossed the road (see here). Cranes emit a low rolling purr in order to keep in contact with each other. I was able to pick up a short burst of that intimate purring, although it is audible only in the first few seconds of the recording (purring cranes).

So, I guess it’s safe to say that up close and personal these birds are simultaneously cuddly, artful, and somewhat filthy.

1 Comment »

  1. Wow, what great photos. I was scheduled to take part int he Audubon crane count in Washtenaw County last weekend, but I ended up having the chance to go to Chicago, so I missed it. I was really bummed to have missed them, but your photos make up for it!

    Comment by Monica — April 25, 2009 @ 7:49 am

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