Monday, August 19, 2013

Like a bat out house

My children are truly wonderful young people and not particularly given to shrieks of panic.  So when all three screamed in unison this evening I took it seriously.  The cause of the hysteria was a large bat flying around the living room.  I had been working on the driveway and closed the garage doors when I was finished.  Evidently, the bat had flown through the garage and up from the basement into the house...where my children were waiting.

I suppose I could have called animal control and had them show up when they could.  They might search the house or use their knowledge and experience to come up with a solution? More likely they'd polietly tell me to grow up and open the doors.  Instead I decided to deal with the problem myself based on the potentially flawed logic that a reasonably well informed biologist could take care of a biological problem.  So I gathered my children in a bat-free room, closed the door and set to work.

The bat had come to rest in curtains and when I approached to open the windows he or she took a bat out of...curtains?  As the bat flew in rapid circles I grabbed a tall narrow trash can and a lid.  I turned on all of the lights in the house to more easily track the bat, it's shadow, or reflection from room to room.  A second landing in a different curtain lead to a failed attempted capture.  After flying around the living room for at least 10 minutes he started to explore the rest of the house and found his way upstairs.  I closed as many bedroom doors as I could to narrow the options for both of us.

As I approached the only remaining bedroom door, the scared and exhausted bat came to rest on the top of the door frame - perfect!  Somewhere back in my lizard brain I remembered that bats need to drop to take flight so a container underneath seemed like a reasonable solution.  I brought the trashcan up underneath the bat and as soon as the rim made contact with the door frame the bat obligingly dropped in an attempt to fly once more.  I popped the lid on top.  As efficiently as I could, I brought can/lid/bat down stairs and out the front door.  I dumped the worn out bat on the grass near a tree and gave him all the space he could wish for.

So what take-home message should there be?  It's worth remembering that bats like any scared animal can bite and they do carry rabies.  Bat populations are dwindling in parts of the United States and Canada because of white-nose syndrome.  Avoiding direct contact by trying to kill a bat is good; releasing a live bat to consume lots of insect pests is good also.  The Humane Society offers advice on dealing with trapped bats. One piece that differed from my approach was to tilt the container towards a tree trunk so that the bat can climb high enough to drop and fly....good advice for the next time.  They also recommend thick gloves.  And if you are bitten??  Get medical treatment as soon as possible; untreated rabies is fatal.

Bat image is from Wikimedia Commons.

Friday, May 3, 2013

Burn baby burn

Fire in Camp Johnson; photograph courtesy of Peter Hope
Before proctoring my Evolution lab today I caught a whiff of the sweet smoky smell of burning leaves.  If I lived in a California wild-fire zone I might have worried.  Even in Vermont the smell might be cause for concern; we have had 9 days without rain and a pleasant week of sunshine.  The National Weather Service has advised against lighting fires and indeed there was a localized forest fire during the past few days.  My lack of concern is based upon some insider knowledge.  My colleague Peter Hope has been conspiring or should I say collaborating with a consultant, the military, and conservation biologists to burn some patches of sandplain forest for some time now and I knew that today was the big day.

Sandplain forests grew in much of Chittenden County Vermont before the area that is now the Saint Michael's College campus was cleared for farming by European settlers. The sandplains formed when rivers including the Winooski deposited sand and built deltas in Lake Vermont, and then the Champlain Sea.  As glaciers receded they dropped materials to the south forming a terminal morain that functioned like a dam containing the meltwaters from the glaciers forming what geologists call Lake Vermont.  A layer of finely ground 'rock flour' that settled from the melt water can still be found beneath what is now Lake Champlain.  The weight of glacial ice that was literally miles in thickness depressed the earth's crust in Vermont below sea level.  When the glaciers melted back as far as where the Saint Lawrence River mouth is today, sea water flowed in forming the Champlain Sea.  Eventually post-glacial rebound brought the Champlain Valley above sea level and the deltas were lifted above the water level.  Modern-day Lake Champlain is roughly 100 feet above sea level.

Because of the very sandy soil in these old deltas, the forests tend to be adapted to well-drained dry soils and would be expected to periodically burn following lightening strikes.  The pitch pine is a tree species example that is one step beyond fire tolerant and is actually fire dependent.  Pitch pine cones open only after fire and the seed can only grow when the organic matter layer on top of the soil is burned back to bare sand.  In the Gil Brook Natural area where fire is suppressed, we can see that the pitch pines are gradually dying out and being replaced by white pines.  Coincidentally, a patch of Gil Brook accidentally burned this week and it will indeed be interesting to see how this affects the vegetation there.

The planned burn in the sandplain forest in Camp Johnson this week was designed to burn off most of the organic layer and facilitate growth of the natural vegetation including pitch pines.  The 2013 burns are just the latest in a series of burns implemented to preserve the sandplain forest and perpetuate the heath-like vegetation that would have dominated this region before European settlement.

For a number of years, Saint Michael's College students enrolled in General Biology have sampled insects, trees, and plants in both Gil Brook and Camp Johnson.  These efforts were complimented by intensive sampling by students under the direction of Valerie Banschbach and Peter Hope last summer in the areas slated to be burned.  Post burn sampling will happen this summer and the Fall General Biology class will be the first set of students to sample from recently burned forest plots.  It's a lot of fun to work with students on real research questions during the course of regular classes!

Friday, April 12, 2013

Your child's first microscope (or a gift for your grade-school teacher)

This post can be summarized thus: Buy a used dissecting scope on Ebay.

Parents and grandparents love to purchase microscopes for their favorite children.  My parents did; and I did the same for my kids.  Perhaps we are motivated by the idea that we can stimulate interest in science?  Personally I like the motivation but not the potential result of a poor purchase choice.

Toy manufacturers market cheap plastic compound microscopes with poorly mounted optics and underpowered battery-operated light sources.  I think that these toys are truly junk and likely to lead to frustration rather than deep fascination for science.

Looking past the quality issue, the more fundamental issue is the choice of microscope type.  Compound microscopes magnify 100 or more times and are great for looking at the scales on a fly's wing mounted on a glass slide.  Light shines through the specimen and the more you magnify, the more light you need to see anything.  The maximum magnification on some of these scopes is often non functional as a result.  Only thin specimens or slices of specimens through which light can be transmitted will work.  I suspect that many kids starting out would rather look at the whole fly.  And by the way, could we skip the whole glass slide part?

This is where dissecting (AKA stereo or stereoscopic) microscopes come in.  A child or college professor can pop an insect, coin, or fossil onto a dish or piece of paper under a dissecting scope without slide mounting and get a good look in seconds.  Because they typically magnify in the 10 to 40 X range, you see the whole organism and can get by with room light or with a flashlight.  Chunky specimens like fingers and coins are fine because stereo scopes make use of reflected light.  My five-year-old daughter had no difficulty examining insects, twigs, and rocks using an old dissecting scope and natural light on a picnic table at a camp out last spring.  In fact she spend close to 2 hours hauling her spectacular finds out from rotting logs and proudly sharing the view with anyone and everyone near by.

Other big advantages of dissecting scopes include large depth of focus and deep working distance.  In other words, more parts of thick specimens will be in focus at one time than under a compound scope; and there is more room to place specimens between the lenses and the stage.  And I did mean 'lenses'; there are two aimed at slightly different angles resulting in a 3D view of your specimens.

So what might you purchase?  Some very nice stereo microscopes made in the 50s, 60s, and 70s by American Optical were in use in schools and colleges across the country and in many cases still are.  Many have found their way into the used market and are plentiful on Ebay.  Search for "American Optical forty" (photographed above) and expect to pay between $50 and $150.  My search revealed 8 today, and the number is low because I purchased 8 last week for an outreach program.  These scopes are heavy, stable, and durable.  They come with built-in lights and two levels of magnification.

Tweezers from your nearest pharmacy make great forceps (and with your new scope you can more readily and gently remove splinters).  Plastic lids from jars are a great substitute for Petri dishes and will protect your microscope from scratches.  Medicine droppers are worth having and usually come 2 on a card for under $4.  Need a plankton net?  Use a nylon stocking and a coat hanger.  Drop a baby food jar down into the foot and secure it with rubber bands around the neck.

If you find that your budding scientist is spending a lot of time on the microscope and getting serious about things, you could consider trading up......

Wednesday, February 13, 2013

You've got a lot a gall....

Wouldn't it be great if a teacher and students could study a plant, its herbivore, and the predators of the herbivore?  Ideally you'd want to study these three trophic layers of the system in a single class session, or perhaps two.  Of course, as an educator, you'd want all of this to happen very cheaply, or better yet, for free.

Warren G. Abrahamson, his colleagues, and a host of students have been working with just such a system for many years.  They have generously provided all of the tools necessary for teachers to share this system with their students.

Goldenrod species are found in most places in the United States and in many locations they are unwitting hosts to the goldenrod gall fly.  Female flies lay eggs into the growing tip of the goldenrod.  Chemicals released by the hatchling larva cause the plant to form a corky spherical gall about the diameter of a quarter coin.  The larva spends about 50 weeks in the gall feeding on plant tissue, growing, and pupating, before emerging as an adult to complete the life cycle.

Students in my evolution class collect a sample of about 250 galls during the first week of class in mid January.  For two years in a row now we have completed the task without the need for snowshoes.  We number and then measure the diameter of each gall using a plastic artist's templates designed for drawing circles of increasing diameters.  Next we carefully split the galls using pruning shears and use Dr. Abrahamson's online key to determine the outcome of the gall fly's efforts. I would say that the pruning shears are perhaps the most important tool for success with this research project; asking 20 students to cut hard spherical objects using knives might be a recipe for disaster.  As much as I respect and admire the work of the Saint Michael's College Rescue Crew, I'd rather not set myself up to need their services.

Gall fly larvae represent a high-protein meal when most other insects are underground.  A number of predators and parasitoids take advantage of the bounty.  Woodpeckers, chickadees, beetles, and wasps all partake in the fly larva feast.  In our most recent foray into the world of gall fly biology, we observed that already by January, 70% of the galls no longer housed gall fly larvae.

The entire sample of galls serves as a 'before predation' example; the subset that still contains viable fly larvae represents the 'after predation' survivors.  The data set is perfectly amenable to graphing using histograms and statistical analysis.

As predicted in the published literature, my students found that 2 bird species accounted for most of the larger galls, and many of the smaller galls hosted wasp rather than fly larvae.  The student data set shows strong evidence of stabilizing selection.  It seems that it is in this case better to be average than to be exceptionally large or small. 

By coincidence, my daughter's first-grade class used galls as a study system for life cycles and food webs during the same time period.  The first graders did not want to kill the larvae and so I was assigned to release them to 'the wild'.  The larvae sat in my car in a paper cup during a day when the temperature dipped to several degrees below freezing.  The larvae were as soft and squishy as when they were removed from the galls, despite the fact that my water bottle in the same car was frozen solid.  It was a nice illustration of the antifreeze properties of the larval tissue.

We will revisit the gall fly population on campus late in the semester to see if additional months of exposure to bird predation has further reduced the proportion of surviving flies. Dr Abrahanson's generosity in sharing what he has learned serves as an example to all of us academics studying our sometimes obscure topics.  We have each in our own way figured out how to wring data from all sorts of bizarre systems.  There are tricks that we have learned from colleagues or gleaned from conferences.  We should share these tips! 

The images used on this page are from Wikimedia Commons:

Wednesday, January 23, 2013

Digital Coyote

Large natural history museums typically display only a tiny fraction of the specimens that they house.  Unlike art museums, natural history museums frequently place replicas in the public view while the real specimens are stored under the watchful eyes of curators and back-room researchers.  Access to stores of research specimens is tightly controlled and can involve a written application that is vetted by other scientists.

Much of the research and education that could be done on preserved specimens requires large numbers of replicate individuals so that statistical analysis can be used to support the conclusions we may draw.  Hands-on access to a large collection is beyond the reach of many small institution researchers and out of the question for most teachers.

To address this disconnect between education and museum collections in a small way, I decided to create a virtual museum.  I first accumulated enough coyote skulls from diverse locations to provide a hands-on activity for my own students.  Next I recruited two bright hard working students to very carefully photograph each skull with a scale bar in place.  From an initial collection of about 10 found skulls, I have expanded by contacting taxidermists and ebay sellers from around the country.  I now have more than 60 carefully numbered and curated coyote skulls.

The virtual museum is slowly coming together.  We photograph each from left, right, top, and bottom and include a ruler in each photograph.  Thus far we have uploaded 35 sets of photographs and made them available on Wikieducator.  We have found that the skulls can be measured from the photographs within 1mm of accuracy.  A small number of the skulls were treated using bleach and will deteriorate to dust over time.  For these crumbling skulls our photographic record may be the only one that survives.

Using the online collection, it is possible to compare populations from east and west and also to look at latitudinal gradients.  The site may also be applicable to statistical courses in that students can generate their own data rather than relying on fake data.  We hope to also add a collection of domestic dog skulls to illustrate the difference between naturally selected species and an artificially selected domestic species.  The chiwawa skull photographed next to a grey wolf above is an example from that collection.