The Power of Scent

Cody Harris, a talented senior wildlife student and avid trapper, recently whipped up a batch of "lure" and asked if I would be willing to test its effectiveness in the T.A. forest. Testing the lure with the game camera offers the opportunity to not only keep track of the species drawn in but also observe their reactions to this potent concoction. Trapping lure is a scent laden substance used to attract a variety of furbearers (creatures whose fur is commercially valuable). Cody's recipe reminded me a lot of a halloween witch's brew including things like beaver tail, dear meat, and fox urine. I have been using small amounts of the lure in front of the game cameras around the TA forest for the past couple of weeks and the verdict is in. This stuff works!

The species captured over the past few weeks stopping in to give the lure a sniff include gray squirrel, gray fox, red fox, porcupine, opossum, raccoon, and coyote. Some of the most notable videos are shown below.

This porcupine spent a while investigating the scent lure left on the upright stick. 

This red fox surely picked up some the pheromones from the fox urine in the lure and left a scent mark of its own. 

The coyote shown in the video strikes a perfect pose while remaining wary of any danger. 

A pair of coyotes arrive on the scene later on the same night to investigate the scent lure. 

One of the most notable observations from the use of the lure was the territorial behaviors it generated from some of the species. The red fox shown above leaves a scent mark of its own before departing. It is certainly possible that the presence of fox urine in the lure could signal the arrival of an intruder on its territory. The pair of coyotes shown in the last video is another highlight. The individual seen in the background seems a little rotund for the time of year and it is possible that this could be a female late in her pregnancy. Coyotes in Maine generally have their pups between late March and May making the timing almost perfect. 

Vernal Pool Fun

My spring semester wildlife students have been working hard for the past week learning all about vernal pools and the amphibians that call them home each spring. These ephemeral ponds in the woods are one my favorite topics to teach to high schoolers. It is one of the few instances in my Maine Fish and Wildlife course where we can learn in detail about a group of species and then march outside as a class and observe them in person. That is exactly what we did last week on Thursday (3/31).

Listening as a class for the duck-like chuckle of the wood frog.

Seasonal pond in the forest must satisfy three basic requirements before they can be classified as "vernal pools" and receive some extra protection. 

       1. Vernal pools are temporary bodies of water and typically dry up by late summer or early 

            fall.

       2. There must be no fish present. 

       3. Vernal pools should show signs of use by one or more of the indicator species listed 

            below.

              a. Wood frog (Rana sylvatica)

              b. Spotted salamander (Ambystoma maculatum)

              c. Blue-spotted salamander (Ambystoma laterale)

              d. Fairy Shrimp (Anostraca)

On our most recent visit, students got to witness two of the four indicator species in their natural environment. Wood frogs were both heard and seen floating around in the pool. Their softball sized egg masses were also visible clinging to vegetation in the water. A haul of a trap left overnight yielded two male spotted salamanders. The spotted salamanders are a real treat for the students as their size (up to 7") and striking coloration is unforgettable. These members of the mole salamander family are rarely seen outside of their springtime march to the vernal pool as they spend the remainder of the year deep underground in small mammal burrows or natural crevices in the forest. 

A close-up look at a wood frog, the first arrivals at vernal pools in the spring. 

A spotted salamander fresh from the vernal pool. 

The activity around the vernal pool as come to yet another screeching halt as winter refuses to release its grip on the landscape. The vernal pool ecosystems and their fragile amphibian inhabitants immediately come to mind whenever I see a springtime cold snap in the weather forecast. The good news is that wood frogs and spotted salamanders have existed on the Maine landscape for a lot longer than I have been worrying about them. They have evolved systems to handle brief dips in the mercury like the one we are currently experiencing. As long as temperatures don't get too cold for too long, they are able to wait out the snow and ice at the bottom of the pool or in nearby leaf litter before resuming their breeding activity again.

T.A. Squirrel Project Update

After an extensive permitting process and some small mammal handling training last fall, the Thornton Academy Squirrel Project was born. This is an ongoing research project focusing on the eastern gray squirrel (Sciurus carolinensis) population at and round T.A. Working with my Maine Fish and Wildlife Students and two dedicated lab aides, we caught and collared ten squirrels in the forest near the eastern trail. These squirrels were fitted with green poly-coated wire collars, each with its own color coded crimp. Our main goal was to estimate the population of gray squirrels on campus.

An example of the collars our study squirrels are wearing. 

This form of population estimate is known as "Mark and Recpature". Typically we would have continued trapping and recording the ratio of collared to non-collard squirrels in our traps as the year went on. In leu of the gray squirrel's learning abilities and tendency to become tougher and tougher to trap the more they are handled, the study was designed using a trail camera and feeder station during the recapture phase. Rachel Richard and Victoria Renell, both seniors pursing higher education in the natural sciences next year, were lab aides tasked with checking traps and then maintaining the feeder and trail camera setup. Each day, they would swap SD cards in the camera and sift through hundreds of photos recording the number of squirrels visiting and how many of them were sporting a stylish green collar. In all, they sorted through over 13,000 photos during the monthlong recapture period!

 This was the largest squirrel in the study with a pink/green crimp on her collar.

This squirrel cooperated and held the feeder open long enough for our T.A. sticker to come in clearly.

At the end of year one, our math indicated a population of nineteen gray squirrels roaming the T.A. forest around the Eastern Trail. However, as is often the case in science, our initial findings seemed to yield more questions than they did answers. How far squirrels will travel to visit a feeder and the mysterious disappearance of seven out of the ten collared squirrels left us puzzled and looking for ways to figure these questions out. Hopefully we will get closer to answering these questions in year two, stay tuned.

Last week, I filled the feeder with corn and set the camera back up in hopes of checking-in on some of our study squirrels. It didn't take long for them to show up. A female initially captured October 5th last year was documented on the feeder multiple times over the course of a few days. This has been our most reliable collared squirrel with a seemingly small home range. We had some of the usual non-squirrel visitors as well including a raccoon that spent hours enjoying the corn from the feeder over the course of the week.

Our first study squirrel looking healthy nearly six months after her initial capture.

No collar on this one, just a great shot that I had to share.

Our night time squirrel cam visitor. 

Vernal Pool Showing Signs of LIfe

Vernal pools are seasonal bodies of water overlooked by many. They are essentially wooded swamps or puddles in the forest fed by snow melt and spring rains. To a conservationist and amphibian enthusiast like myself, a vernal pool is like a hidden gem. We are lucky enough to have a vernal pool within walking distance of my classroom and my second semester wildlife students will soon begin to learn about these critical pieces of habitat first hand out in the field. I have been using a game camera to monitor our newly installed wood duck box in one of the nearby vernal pools since its installation in February. In that time, we have gotten images of a gray fox and raccoon scurrying across the ice near the nesting box but since our recent thaw, the images have tapered off.

A raccoon crosses the frozen vernal pool earlier this month. 

The camera was originally placed in this location in an effort to capture wood ducks in the vernal pool possibly entering/exiting their newly installed nesting box. While there has been no such luck yet, we received some bonus images and video over the weekend. Gusty winds last Friday afternoon triggered the camera and wood frogs (Rana sylvatica) can be seen floating in the water below the nesting box. Wood frogs are one of the first amphibians to emerge from dormancy in the spring. Shortly after waking up, they travel to the same vernal pool that they emerged from to produce the next generation. They leave tennis ball sized egg masses containing hundreds of eggs attached to sticks and vegetation in the pool before heading back to the forest where they will spend the rest of the year (hence the name "wood frog"). The individuals shown in the video below are most likely males that have shown up early due to last weeks warmth. I got reports of male wood frogs calling from this vernal pool as early as 3/14 and witnessed the "duck like chuckle" of a wood frog chorus at this site personally on the afternoon of 3/16. There are a handful of egg masses now in the pool but it is obvious that few females have shown up at the pool thus far. They are typically a week or so late to the party. In the mean time, the males float around the center of the pool calling and defending their small piece of the puddle in a behavior known as lekking. 

Look closely in the water below the nesting box to spot the wood frogs.

Today's spring snowstorm is sure to put a delay on the breeding activity at our vernal pool. Being ectothermic (cold blooded), a wood frog's body temperature is reliant upon its surroundings and they are only active at temperatures in the upper 40s or beyond. In classic Maine fashion, just as the warmth of spring seems fully upon us, mother nature has other ideas. The wood frogs that have already arrived at the vernal pool will most likely re-enter dormancy and await the next warm up to resume their breeding activity. 

Conditions this morning at the vernal pool. 

The Real Groundhog Day

The den site has yielded yet another mammal species and trail camera first for T.A. grounds. Last Friday afternoon, a no doubt groggy woodchuck (AKA groundhog) was observed freshening up the entrance to the den. Woodchuck emergence is a sure sign of spring on the landscape here in Maine. These are one of the state's only true hibernators. Most woodchucks sleep from late September or early October all the way through to March. Their body temperatures, heart rate, and breathing drop to amazingly low levels. As mentioned earlier in this blog, a hibernating woodchuck physically cannot wake up, meaning that our manmade "Groundhog Day" is completely staged. We very well may have just witnessed the real groundhog day in the T.A. Forest and while its shadow is visible on the ground in the video, it doesn't look like it notices.

Watch as this woodchuck emerges from the den then stands to watch for danger.

I was pretty sure that this den had been originally excavated by a woodchuck but was unaware that it was still being used by one. Woodchucks create elaborate underground dens with tunnels traveling more than 20ft. They almost always have at least one other entrance for emergency escapes. Woodchucks will use multiple den sites throughout the season as food sources fluctuate. This individual could have spent the entire winter in this den or may just be checking after emerging from another site nearby. Being a diurnal creature (active during the day), it also provided us with some color photos and video for a change.

A Multispecies Weekend

Our den site game camera in the T.A. forest captured six species in three days on the weekend of February 26th. Two raccoons, a porcupine, an opossum (Didelphis virgiana), a red fox, a gray fox and a skunk were all documented checking out the den. The porcupine and opossum were both game camera firsts for T.A. grounds!  All of the aforementioned species yield altricial offspring. This means that their young are born eyes closed, immobile, and all around helpless. Raising altricial offspring typically involves the shelter of a den. Many of these creatures are currently within their breeding seasons and there is no doubt that some of them are inspecting the den as a possible site to raise young in the near future. Most seem to give it a quick sniff, sometimes a scent mark of their own, and then they are on their way. All of the species were caught on video with the exception of the skunk shown below in a still image.

The raccoons were the first species to show up at the den over the weekend.

The porcupine was the next species to arrive. 

This was the first opossum I have documented on the game camera behind T.A. 

This red fox ventures half way into the opening.

The gray fox shown above was only 20 minutes behind the red fox.

This "leap day" skunk showed up, marked the ground, and left before being captured on video. 

Wood Duck Box Installation

Last week I was assisted by some dedicated wildlife students installing a wood duck box in one of the vernal pools behind T.A. During our trips outside to monitor amphibian reproduction last spring, we would regularly observe wood ducks (Aix sponsa) feeding and resting in this hidden wetland. Wood ducks are one of the most common freshwater duck species in Maine but few residents are ever lucky enough to see them. They are extremely secretive and prefer hidden marshes and wooded swamps. More often than not, only a fleeting glimpse is allowed of these beautiful waterfowl as they hide or flush immediately once they become aware of human intrusion. Wood ducks are one of several species of cavity nesting ducks native to Maine. This means that they utilize holes in hollow trees for nest sites. Wood duck numbers dipped extremely low during the early to mid 1900's due to overhunting and deforestation that removed many of their natural nest sites. The introduction of wood duck boxes is seen as a major conservation success story and is thought to be one of the leading factors in their recovery.

Winter is the best time to install a new box as the frozen pond provides a sturdy platform to work from. With the help of Jake, Rachel, Sarah, and Victoria, we were able to have everything ready to go in less than an hour.

Picking out the perfect location.

Mounting the box to the pole.

Wood shavings are used at the bottom to help with insulation and provide a base for the hen to build her downy nest. Note the grooves cut in the front wall to aid the ducklings in their climb to the entrance.

The final product. A predator guard was placed on the post to keep raccoons, minks, and squirrels from raiding a future nest.

We plan to use a game camera to monitor the box once the wood ducks begin to arrive this spring and are hopeful that they choose to take up residence. This setup could support any cavity nesting bird however. It will be interesting to see if anything uses the box this year. 

Special thanks to my father in law, Pete Albert, for building us a perfect wood duck box and Allie Hanright for photographing the project.