Tuesday, March 24, 2009

A Missile with Feathers

Monday morning I caught a glimpse of a bird streaking past the window of the Naturalist's cottage. Initially I didn't pay a lot of attention to what it may be and assumed it was a Mourning Dove coming in for a landing in the yard. Eventually my curiosity got the best of me and I went to the window to have a look around. I didn't find the dove.

The bird streaking past the window was a Sharp-shinned Hawk. Apparently it was making a divebomb onto an unsuspecting American Robin. In the top photo the little hawk has already begun to pluck the feathers and dismember the the robin (the dark grey thing it's standing on is the robin). The picture is a little blurry from me shooting through the window and busy from all the leaves, but you might be able to see the red breast of the robin in front of the hawk's right foot.

The hawk's breakfast soon attracted the attention of an American Crow. Though the crow(17-21") was certainly larger than the sharpie (10-14"), it stood it's ground and refused to give up it's meal. Above you can see the sharpie finishing his breakfast of champions.

Sharp-shinned Hawks belong the group of hawks known as Accipiters, which also includes Cooper's Hawks and Northern Goshawks in this part of the continent. Accipiters have long tails and short, rounded wings, making them adept at hunting their main quarry: other birds. Small, woodland birds and mammals become quiet and still when these birds are suspected of being near. Nothing strikes fear amoungst song birds like the presence of Sharp-shinned and Cooper's Hawks.

They attack with suprise at a high rate of speed and are exceptionally aggressive and relentless when pursuing their prey. I've witnessed a Sharp-shinned Hawk chasing American Goldfinches and Black-capped Chickadees around and around the gnarled branches of an apple tree. When one bird attempted to make a break from the tree for another safe haven, the sharpie snatched it straight away. This winter I watched a Cooper's Hawk make a dive at the bird feeders behind the museum and miss on its first attempt. Most of the sparrows fled into the pile of Christmas trees we had placed nearby, but their location was not lost on the Cooper's Hawk. The hawk landed right on top of the pile of trees, reached in with one foot, and grabbed a sparrow within a matter of seconds.

Sharp-shinned Hawks are migrating back to our area now. Funny how they're arriving about the same time as some of the other migrants (read robins)? Keep an eye in your yards and on your bird feeders. You may be offering more than just seeds this time of year!

-Adam Zorn, Naturalist

Monday, March 23, 2009

Mycoplasmal conjunctivitis and Finches

This winter/spring we have witnessed a handfull of goldfinches and house finches acting oddly at the bird feeders. These birds would fly from feeder to feeder more like they were lost than with the usual confidence one would expect from a bird. These same birds were often the last to respond, or didn't respond at all, when other birds quickly flee from the feeding station. Sometimes they'd shake their heads in fits or could be found sitting motionless on the ground, looking lost, amoungst a hungry group of sparrows and juncos. With a good look through the binoculars, we could see these birds were not healthy.

These birds were exhibiting the telltale behaviors of a bird with Mycoplasmal conjunctivitis. Conjunctivitis, as it is usually referred to, is a respiratory disease caused by the M.conjunctivitis bacterium. The physical symptoms of the disease include crusty, swollen tissue around one or both eyes, or thoroughly red, swollen, and oozing eyes in severly infected individuals, resulting in virtual blindness.

Goldfinch showing symptoms of conjunctivitis at my feeder

The same goldfinch trying to see from the swollen eye

The goldfinch in the photos above was seen for two days at the cottage feeders. That was Day 1, when he could still open the left eye and barely see from the right eye. The next day I saw, presumably, the same goldfinch with more advanced symptoms sitting on the ground trying the scavenge any seeds it could manage to find. I didn't see it after the third day.

Conjunctivitis is most common, and was first reported, in House Finches. The first reports of this disease came from the Washington, D.C. area in the winter of 1993-1994. From there it has spread all the way up and down the eastern US and Canada. Obviously goldfinches are susceptible to the disease in addition to Purple Finch, Evening Grosbeak, and Pine Grosbeak.

There is still a lot of mystery about the disease, including how finches have contracted it without other species showing no signs of infection, how it is spread, and how much of an impact this type of infection has on those species' populations that are affected.

Common sense and general rules to prevent the spread of avian disease apply when birds with conjunctivitis are noticed at a feeder or feeding station:

If diseased birds are observed at the feeders, take them down and wash with a 10% bleach solution. Spread feeders out to reduce crowding. Rake the area under the feeders to remove moldy seeds and bird droppings. You may want to remove all feeders for a day or two to break up a high concentration of feeding birds while ill birds are in the area. Most birds with the physical symptoms are unlikely to return to the feeding station after a day or two, due to the fact that they're likely to pass from starvation, over-exposure to environmental conditions (cold, snow, heat, rain, etc), or predation due to their loss of vision.

We have recently removed all of the seed feeders from the museum feeding station and at the naturalist's cottage. Having done so has resulted in the dispersal of the numerous house finch and goldfinch flocks from the feeding stations. The birds are still around and quite capable of locating other food sources. We are expecting to place the feeders back out later this week now that most of the birds have dispersed.

The technical information for this blog was taken from the House Finch Disease Survey, a project of the Cornell Lab of Ornithology. Visit their website for more information about conjunctivitis and learn how you can participate in the survey.

Adam Zorn - Naturalist

Saturday, March 21, 2009

1st Day of Spring...Take 2

The first day of spring 2009?

So, yesterday (March 20, 2009) was supposed to be the first day of spring. Well, the photo above looks more like the first day of winter to me. 8am and the snow is coming down. "It will only last a few more minutes" I told myself as I looked to the sky searching for any sign of blue. Unfortunately is was nearly 11am before the flurries faded and the sun started to peak from behind the darned clouds that dropped all that snow.

Today, spring has decided to make it up to us here at the sanctuary. Despite the chilly 29 degree air, cardinals, titmice and chickadees were singing bright and early this morning. Not to be outdone by anyone's displays of territoriality, a group of 10 turkeys made an appearance in the yard this morning. 10 in all (3 toms, 7 jakes) made their way out of the pine stand on the Easy Loop trail, past the cemetary and into the lawn in front of the naturalist's cottage.

I couldn't get them all into the frame of the camera, but you can see half the crew here on the right. I had to take the picture through my windows so I wouldn't scare them off or disrupt the display of one particular male. This shot shows two toms (one displaying on the left and the other to the far right) and three jakes. The toms are the one's most likely to take a harem of females this spring, while the jakes will seemingly hang around as long as the toms will let them. I'm guessing this display was all about reminding the other boys in the group who's the boss. It doesn't hurt to get a little practice in before showing off for the girls, too!
Other sites and sounds from the morning includes a pair of Eastern Bluebirds eating bugs in Nichols Field and checking out the nesting boxes. The male was singing and telling his girl all about the great place he had found to make a nest. That was a sign for me to get our nesting boxes all cleaned out.

A number of robins were foraging for insects in our neighbor's field adjacent to the Catbird Trail. Tufted Titmice and Carolina Wren were calling out through the forest. A Downy Woodpecker was drumming on a tree, setting up the boundaries of his breeding territory.

-Adam Zorn, Naturalist

Monday, March 16, 2009

Emerging Frogs

This weekend's mild weather has put the wheels of spring in motion. According to the calendar, spring begins this Friday, May 20th. But nature has no plans on waiting for next friday. The purple sheaths of the Skunk Cabbage's flowers are emerging from damp soils near Bechtel Lake. Tufted Titmice have become increasingly vocal and territorial. I saw my first Eastern Bluebird of the spring behind the cottage this past week as well.

One of the surest signs of spring is the chorus of frog calls that ring out from our swamps, marshes, vernal pools, ponds, and lakes. Saturday evening I was out for a walk to check on the status of the vernal pool located on top of the Wood Thrush trail. The size of this body of water varies from year to year depending on the amount of winter snowfall and spring rains that fill this small depression in the earth. Upon reaching the pool I was pleasantly suprised with the amount of water. More water equals more success for the amphibians planning on breeding in this relatively temporary body of water. In dry seasons, the pool dries up, leaving any undeveloped amphibian larvae unable to complete their metamorphosis.

On my way back down the hill, as the sun began to fall behind the hills, I heard a couple of hardy spring peepers calling out into the evening air. Though these frogs are quite small, one peeper can produce an ear-ringing song. Much of their vocal prowess is due to the ballon-like throated from which the sound originates. As you can see from the photo above, a calling spring peeper seemingly increases its overall size by 25% when its throat is fully expanded. Peepers calling in the evening and night hours to remain out of sight of potential predators. This sort of activity could get a frog eaten if done during the daylight hours.

Another common, but often overlooked, frog breeding in the cool temperatures of early spring are the wood frogs. This species is a bit larger than the peepers, but their calls are less obvious, especially when both species are breeding in the same body of water. The wood frog (photo right) is especially fond of vernal pools. If found in good numbers, a collection of breeding wood frogs sounds like a bunch of ducks quacking with sore throats. These guys leave copious amounts of eggs attached to submerged sticks along the edges of the vernal pools. This frogs can often be spotted in the daytime hiding in the water if you look closely. Their breeding behavior is much easier to observe than the spring peepers.

Soon to come, after the first warm spring rains, will be the emergence of our local breeding salamanders, followed by the pickeral frogs, toads, green frogs, bullfrogs, and grey treefrogs. If you'd like to learn more about these animals, please join us this spring for one of our spring hikes or amphibian walks.

-Adam Zorn, Naturalist

Sunday, March 8, 2009

Reptile Sightings in March

This weekend's warm weather has created an abundance of wildlife activity around the sanctuary. Saturday morning's bird walk was full of bird song - mostly chickadees and titmice with a few robins, white-throated sparrows, and juncos filling out the chorus. The ice has begun to melt from the surface of Bechtel Lake and Lost Pond, exposing some open water along the south-facing shorelines. Hikers on Saturday afternoon spotted one of the muskrats swimming through the band of open water in Betchel Lake.

In addition to the mammal and avian activity, there was a garter snake spotted right in front of the naturalist's cottage. The little guy was sunning himself on the flat rocks making up the walkway. The picture above is of a different garter snake peeking out from a rock crevice last summer.

The garter snake wasn't too much of a surprise since temps were in the 60's and I've seen garter snakes as late into the fall as early November when temperatures can be much cooler. The biggest surprise of the day was a painted turtle seen sunning itself on top of a log over the ice at Lost Pond. He was spotted by pair of hikers in the mid-afternoon sun. What a treat it was for them to see this creature so early in the year. We normally wouldn't expect to see a painted turtle until late March or early April. This turtle even beat the spring peepers out of hibernation! If moderate temperatures continue to persist, keep your ears perked for the "jinglebell" sounds of the spring peepers in the coming weeks.

-Adam Zorn, Naturalist

Sunday, March 1, 2009

Sugaring Squirrels

The squirrels around the museum and cottage are an endless source of amusement and/or aggravation (it depends on what they're up to and what day it is). Through the last three years, we've seen the squirrel population double year after year after year. This winter we have seen as many as 8 grey squirrels and 4 red squirrels in the yard or under the feeders.

As their numbers have increased, so too have our observations of their sometimes unique and odd behavior. We observed the red's intolerance of greys present at the feeders, until the ratio reaches about 4 greys to 1 red. At that point, the fiesty red squirrel gives up.

I've seen these guys methodically sort their way through the variety of mixed seed spread all over the ground, picking out their favorite (sunflower seeds) and then going back over the area to devour the cracked corn.

I even watched one individual grey squirrel mark his territory right on top of one of the bird feeders, apparently in an effort to claim that one all to himself.

This is all in addition to the typical squirrelly behavior that involves attempting to climb onto, jump onto, or launch themselves onto any one of the bird feeders that lay just out of their reach.

One of the most interesting things we've noticed of late is the squirrel's version of maple sugaring. At this time of the year, a number of the smaller sugar maples ooze and leak their clear, sugary sap. On warm days, the trunk and branches of these trees look as though they're soaked from a recent rain storm.

Upon close inspection of the trees, we see how they have come to leak so much of their sap. The squirrels have been scoring the bark of the small maples and branches of the larger ones.
On warm days, these wounds drip constantly. The squirrels have been visiting them at different times during the day, licking up the sweet sap. On the days when the sap isn't flowing, the squirrels continue to visit, presumably licking up any residual sugar left on the sap and continuing to score the bark of these trees. I'm sure the maple sap is a sweet treat for the squirrels, just as the boiled down sap (aka maple syrup) is a sweet treat for us.

If you have squirrels and sugar maples around your home, watch for signs of the squirrels indulging their sweet tooth.

-Adam Zorn, Naturalist