Changing Leaves

Fall is in full swing. The sun keeps the air warm, but it's chilly in the shade. Honking geese fly overhead and crickets chirp throughout the lengthening nights. Dried leaves swirls about in the breeze, while those still in the trees for a riot of color. What is going on inside the tree that causes the color change?
Trees are getting ready for a long winter's nap. Like animals going into hibernation, everything is slowing down. Trees have been gorging themselves on sunlight all summer, and now their metabolism is slowing down. The chlorophyll is breaking down and water uptake is stopping. Chlorophyll absorbs all wavelengths of light except green, which is reflected back to us. Without chlorophyll, we see other chemicals in the leaf.

A yellow sugar maple catches the late morning sun

The yellow leaf of a sugar maple

Xanthophyll colors the leaves of aspens, birches, and beeches a bright yellow. It's also found in corn.  Red and purple in red maples and scarlet oaks comes from anthocyanin, which is produced when the chlorophyll stops and the leaf metabolizes extra sugars. Carotene, the same as what you find in a carrot, gives trees like sugar maple and sassafras their orange leaves. Orange can also come from a leaf that is showing both xanthophyll and anthocyanin. Brown, such as in oaks, comes from tannins. Carotene and Xanthophyll are present all year in the leaves, but are overshadowed by chlorophyll.

Another sugar maple, this one decked out in red

This red sugar maple leaf fell of a Canadian flag

The brilliance of each color, as well as the amount of colors relative to each other, are dependent on the weather. If fall is sunny and dry, trees will produce more anthocyanin. Trees will be a more brilliant red. Other years, trees won't produce as much or even none at all and nearly all leaves will change to yellow.
But of course, each tree is an individual so it may change well before its neighbor or have different or more vibrant colors, even among the same species. I've seen red maples that look like traffic lights with red, yellow, and green leaves on the same tree. I've even seen multi-colored leaves.

Brown oak leaf, rich in tannin

Yet another sugar maple, this time in orange

Get out there and enjoy some biochemistry in action before it's too late! The leaves have been great this year, peaking in my area this week and next. Up north you may be past peak, and down south it's on its way! This week's information comes from SUNY College of Environmental Science and Forestry and Montana Natural History Center.

Yellow and brown hickories and oaks basking in late
afternoon sunshine

Species of the Month

With Halloween right around the corner, October's Species of the Month is another creepy crawly. You might be afraid of spiders or bats, but no one wants to see a rat in the house. This month we profile the ubiquitous black rat (AKA house rat, AKA roof rat, AKA ship rat), destroyer of crops, chewer of things, and spreader of plague. 

Halloween rats from Pintrest

Scientific name: Rattus rattus
Kingdom: Animalia (animals)

Class:  Mammalia (mammals)
Order: Rodentia (rodents) 

Range: Worldwide; native to India and Southeast Asia
Habitat: Almost anywhere
Lifespan: Average 1 year, up to 4 years

Black rat (Inventaire National du Patrimoine Naturel)

Diet: Omnivorous, but mainly plant-based (fruits, grains, seeds)
Predators: House cats, birds of prey, foxes, coyotes
Conservation Status: No special protection
Other facts: The black rat was spread around the world by travelers. They are also called ship rats because if their affinity for sailing to new homes on distant shores. The moniker roof rat comes from their climbing skills. They are an invasive pest everywhere outside of their native range, ruining food stores by soiling what they don't consume. They were a disease vector during the plague outbreaks of Medieval Europe, carrying fleas that hosted the virus. While plague is not as serious a threat as it was in the Dark Ages, the fleas on a rat can still spread other diseases to humans and livestock. A similar species, the Norway rat, is just as widespread and will kill the smaller black rat. Despite the headaches caused by both rats, they are important links in the food chain now that they've become established. Hawks, owls, coyotes, and foxes are among their main predators.

Black rat (Australian Environmental Pest Managers Association)

This month's information comes from the University of Michigan's Animal Diversity Web once again.

nm1: 
nm2: https://www.aepma.com.au/PestDetail/96/Black%20Rat

Firefly Watch 2019 Results

Beginning in late May and concluding in September, I conducted observations for Massachusetts Audubon again this year. I count how many flashes I see in three separate periods of ten seconds each. I usually separate those periods by five to ten minutes, to allow for increasing level of darkness. Mass Audubon asks for data other than how many flashes. They also want time and date, weather conditions (cloud cover, precipitation, wind, and temperature), flashing patterns (single flash, double, triple, J-shaped), and color of flashes. Weather may affect firefly behavior, while color and pattern indicate separate species of fireflies.
After two years of submitting observations for my location (my parents' back yard), I don't have enough data to notice any population trends yet. To track population trends, I tried my best to conduct observations on the same dates as last year. This wasn't always possible, like the night I had to chose between fireflies and my daughter's graduation. Guess who won.

Graph of 2018 firefly flashes

Comparing 2018 to 2019, there was a slight decrease in number of flashes but not statistically significant. The first fireflies were seen the same day both years, while the last was seen about a month later in 2018 than in 2019. Peak flashing began almost two weeks earlier in 2019 than in 2018, and following crash was much sharper, without the brief rises that occurred in 2018. My guess is that with a earlier and longer peak, mating was successful and there was no need to keep looking for a date.

Graph of 2019 firefly flashes

What I was told by my mom before I began this project in 2018 was that there weren't really any fireflies around anymore. Since then, I've learned it's not true. She says there are definitely more now, but without any data to back it up I have to take her word for it. I don't remember if there are more or less than when I was a kid. It's not something I was looking at scientifically at the time. I do remember seeing fireflies in September only once before 2018 though. I don't remember what year it was, but I remember they didn't show up until late June, so we had them for the same length of time that I was used to.

Graph showing 2018 and 2019 flashes

Since the end of the season, I moved a few miles away. Despite having to drive a little farther, I will continue observations at my parents' house for consistency. It's hard to establish a trend if I don't use the same location. I may add my new location and start a data set here as well. After getting a second set of data, I am closer to being able to track populations. I am already looking forward to the return of next year's fireflies and the data they'll give me.

Be Bear Aware

With the arrival of fall and the approach of winter, food sources are becoming scarce for some animals. Bears spend the winter either hibernating or in torpor, a state of lowered metabolic and other bodily activities. To prepare, they begin gorging themselves this time of year so they can have enough calories to last through an extended period of not eating. While they generally try to avoid humans, now and when they emerge in spring (very hungry) are the most likely times you will encounter a bear. Here are some helpful tips on how to avoid or survive a bear encounter.

Don't let this happen to you! (US Forest Service)

Hungry bears are attracted to food and will follow their noses. When camping, store food, drinks, utensils, cookware, dishes, cosmetics, and hygiene products in a bearproof container, locked in a vehicle, or suspended 10-15 feet above ground and 4 feet on all sides from a climbable surface. Sleep in a tent or camper away from your cooking area. Don't sleep in clothes you cooked in. Don't set up camp near berry patches, carcasses, and bear signs. Avoid foods with a strong smell like bacon and fish, no matter how good they are. Sleep near your flashlight and bear spray. If you see a bear try scaring it away by making loud noises. If it is undeterred, move away to a safe area.

Ideal camp setup (WildAware Utah)

When hiking, if you see a bear that hasn't noticed you, move away quickly, quietly, and calmly. Never try to run from a bear. Running might trigger the chase instinct and the bear will always beat you in a race. If you see a bear and it notices you, let it know that you are human and  not food or another bear. Talk to it calmly, move your arms about, and keep an eye on it without making eye contact. Hopefully the bear will leave. If it does, walk away in a different direction. If it remains, back away slowly but keep making small talk. If the bear approaches you and is acting defensively- making loud noises moving its head around, or stomping or pawing at the ground, stand your ground. If the bear approaches, it's probably bluffing. Keep talking calmly to it, and start backing away when it stops coming at you. If it comes at you again, stop moving but keep talking until it stops again. If it attacks you, now is the time to play dead. Face down on the ground, keep your backpack on if you have one. If the bear rolls you over, keep rolling until you are face down again. Otherwise, don't move and don't make any sound until you're sure the bear is gone.
If you are faced with a quiet bear that won't leave, you'll probably have to fight the bear or at least make it think you want to. If backing away doesn't keep the bear from you and it is behaving calmly, act aggressively to let the bear know that you are not an easy meal. Yell at the bear, make yourself appear as large as possible, throw things at it, swing a large stick at it, and make eye contact. The idea is to make the bear think that since you are crazy enough to fight a bear, it probably shouldn't be messing with you. If the bear decides to attack anyway, fight back with a focus on its face. If you have bear spray, use in situations where the bear is aggressively approaching you. Make sure you are not spraying into the wind, and don't spray it on yourself as a repellent. Read the instructions.
The reason I chose bear safety this week is because I just had my first bear encounter while camping in Virginia. I was tent camping about 30 miles south of Washington, DC and while I got up to use the bathroom at 1 AM a bear took advantage of my absence and ransacked my campsite. It put some holes in my tent, knocked my cooler off the picnic table, and tipped over my folding chair. What did I do wrong? I had my alarm set for 5:30 AM so I could catch an early train into the city. To move more quickly, I had my next day's clothes and my toiletries in the tent with me. That was my first mistake. My second mistake was leaving the cooler in the open. I had 8 bottles of water and 3 glass bottles of root beer in there. I decided the ice would last longer in the woods than it would in the car when drove into civilization, where it's generally hotter. My third mistake, which wasn't really a mistake but just the circumstances, was not having safety in numbers. Bears don't like people; we have a bad reputation in the animal world. Being off-season in the middle of the week, the campground was pretty much empty. With no people around, maybe the bear felt like the campground was OK to stroll through, and the only tent around was an easy target.

Holes in the tent were on the right side, so I'm guessing
the bear moved right to left, swatting the chair over for
dramatic effect.

When I came back to the campsite, the bear was gone. The tent was a heap, so I spent the rest of the night in the car with the doors locked. Yes, I've seen a news article where a bear gets in a car and steals it.  After sunrise, I inspected the damage. There were holes in the tent, nothing too big but they'll only grow each time the tent is set up. None of the drinks were opened and the glass bottles didn't break. Despite their superhuman strength, bears still need you to open a bottle for them. The chair was fine, but I have no idea why the bear decided to flip it. With a damaged tent, I ended my trip a day early. This week's bear safety tips come from the Grizzly and Wolf Discovery Center right outside fabulous Yellowstone National Park.