Monday, October 31, 2011

Birds eat pumpkins?

This seemed like an appropriate posting for today. My family and I carved pumpkins yesterday and left them outside overnight for the big day. At around lunch time today I noticed that most of our pumpkins had been attacked! I found small triangular dents, suggestive of bird beaks on most of them. The gourds that form the eyes of one pumpkin had fairly deep holes in them; I actually liked the effect. One pumpkin lid was entirely missing.

I took a quick look around online to see if this is a widespread phenomenon and it does not seem to be the case. A host of six-legged pests is listed along with snails and slugs on several pest management sites, but I can find no mention of birds. Perhaps the birds have focused just on me......or not.

I found a couple of blogs discussing pumpkin seeds as bird food with an array of advice (cook them ; don't cook them; sprout them...). One site recommended pumpkins as a source of beta carotene for birds. I can't say I have ever tried to feed pumpkin to birds, but it seems that the birds have helped themselves to them. My kids seemed oblivious to the vandalism, so all was well for the festivities.

Has anyone else had birds feasting on their pumpkins? I see that one person has had squirrels eating his pumpkins and with rather convincing documentation

Thursday, October 13, 2011

Spied a spider?

I recently had the pleasure of spending the night on an island in Indian Lake in the Adirondacks. While foraging for firewood on the northeast end of our island, my son and I found a large fishing spider sitting on a rock. She was carrying an egg mass under her body and sat still for some photographs.

Somewhere I had read that fishing spiders ran across the water surface to prey upon invertebrates trapped in the surface film. I assumed that with a 6.7 cm leg span, this must be the largest spider in our region. But with a little digging, I learned that at least one local wolf spider species is larger.

Far more interestingly, the fishing spider does not limit its menu to invertebrate prey. While they typically consume invertebrates, they are occasionally true to their name and can actually catch fish more than four times their body weight (Bleckmann and Lotz 1987). The spiders use ripples on the water surface to detect prey, including water striders. They move rapidly across the water surface by rapidly retracting their legs and then gliding before again making water contact. All of this happens so rapidly that Gorb and Barth (1994) who described the behavior could see it only using high-speed photography.

View Indian Lake in a larger map

Wednesday, October 12, 2011

Foot prints

How can biologists efficiently collect enough observations to draw conclusions about mammal abundance or diversity in a habitat? This is exactly the problem my students and I tackled in the Saint Michael's College Community Ecology course in the last two weeks. Attempting to observe shy mammals can be disappointing, particularly when moving through a habitat as a group of 20. Instead, our approach was to record mammal footprints at track stations.

Our track stations included a layer of powdered black chalk to blacken the feet of the mammals and a sheet of sticky contact paper to collect each chalky print. All of this was sheltered from rain in a plastic tunnel-shaped structure with an opening at one end. Students determined which habitats to study and we left several track stations in each habitat. We convinced the mammals that walking through chalk and onto contact paper was a good idea by baiting the stations with peanut butter or dog biscuits.

We recorded a total of 355 visits to our 31 track stations over a two week period. We have indeed confirmed that the campus is a grey squirrel and chipmunk haven! Prints were also left by skunks, raccoons, muskrats, and mice. One of the stations with rather smudged prints also contained several black hairs. Microscopic scale patterns on the hairs confirmed our suspicions that the nocturnal visitor was a skunk. Perhaps most interesting, the traps set by the Winooski River were visited by mink; perhaps many mink, or perhaps just one extremely well fed mink with a deep fondness for peanut butter and dog biscuits.