Thursday, October 31, 2013

PSA - Watch Out for Killer Hornets

Asian Giant Hornet (Photo by: Thomas Brown, via Wikimedia Commons, CC BY 2.0)

Back in the 1980s, the world was abuzz about killer bees (officially called "Africanized bees"). Last year, the existence of zombie bees was brought to the attention of the public. Now, somewhat reminiscent of the fictional genetically-engineered tracker jackers from the Hunger Games, we have killer hornets to worry about.

First though, if you happen to come across an article or receive an email saying that giant hornets are mutants created due to radiation exposure from the Fukushima power plant - and that they're killing people in Nebraska - that is false. However, the Asian Giant Hornet (Vespa mandarinia) does exist, and it can be deadly.

True to their name, these are LARGE hornets that live primarily in Asia. They are especially found in Japan, where they are also known as the Giant Sparrow Bee. These insects are about 2 inches long with a 3 inch wingspan. Their stingers are about a quarter of an inch long. As one might imagine about such a large hornet, the sting is quite potent. It has been described as feeling like a hot nail, and the venom contains a neurotoxin and can cause renal failure. Unless you're allergic, a few stings likely won't kill you, even though they will be quite painful and will leave a substantial wound behind. However, if somebody is unlucky enough to receive 10 stings, they should seek medical attention right away. (Of course, an allergic person needs help for any sting).

This year, the hornets have been more aggressive toward humans than usual. Just in China, they killed at least 42 people between July and the beginning of October, and injured over 1,600.

It's not just humans who are at risk from the Asian Giant Hornet. These predatory insects go after other hornets, mantises, and honey bees as well. They use their mandibles to decapitate their victims, and just a few hornets can destroy an entire honey bee colony in a few hours. Not all bees are defenseless, though. If a hornet scout happens upon a Japanese honey bee colony, the bees form a ball around her. They use their muscles to heat the inside of the ball, and they breathe out carbon dioxide. A few bees die, but the heat and CO2 also kill the hornet, which prevents her from summoning others to the hive.

Friday, October 11, 2013

Keep Your Bird Feeders Stocked Through the Winter

Chickadee on a bird feeder (own work)

Some well-intentioned people operate under the misconception that all birds head south for winter. I live in the northern half of the US, and while shopping at my local grocery store last fall, I noticed a display of bird food and bird feeders. I stopped to check them out (my old feeders were due to be replaced). While I was examining a feeder, a young boy and his grandfather walked by. I overheard the boy ask if they could get a bird feeder, and the grandfather said (loudly, as if he was making sure I could hear), “Why would anybody buy a bird feeder this time of year? The birds are all going south!”

Another time, once again in fall, I was having a chat with a former co-worker about backyard birds. When the topic of feeding them came up, he said, “That reminds me. It’s about time to take the feeders down for the winter.”

Actually, as I explained to my co-worker, winter is a great time to feed the birds, even for those who live in more northerly latitudes. While it is true that some birds do in fact head south when the weather starts cooling off, quite a few stick around. Blue jays, cardinals, mourning doves, chickadees, finches, titmice, and sparrows are just some of the birds who are year-round residents. There are even some birds that migrate to the northern US from even further north. I always know winter is almost here when I see dark-eyed juncos hopping around in my backyard.

Food sources for these birds are scarcer in winter than they are during warmer months. Plants aren’t growing and producing new seeds or fruit, and most insects are dead or dormant. If you keep your feeders stocked, you’ll be sure to draw a crowd! I have a few birds who are regular visitors to my yard in summer, but my feeders are a bustling center of bird activity in winter. I also see a much wider variety of birds when it’s cold.

If you decide to offer food in winter, higher fat foods are best. They are higher in calories, and birds burn off a lot of calories just trying to stay warm. Sunflower seeds, safflower seeds, peanuts, and suet are good choices for most birds. If you’re not squeamish about it, you can also offer dried mealworms and insects. Just keep in mind that suet, peanuts and sunflower seeds are likely to draw squirrels and other critters as well. It’s said that squirrels don’t care for safflower, but that seems to vary by region.

Thursday, October 3, 2013

Only Two Bat Species Can Walk

Vampire Bat (Photo by: Ltshears, via Wikimedia Commons, CC BY-SA 3.0)
Whenever we see bats in photos, videos, or even in real life, they are almost always flying or hanging. If you visit a nature center and see a program about bats (or if a bat program comes to your school), you'll usually see them being held in a demonstrator's hand. We almost never see them walking. It turns out that the reason for that is simple - most bats can't walk.

Bats are the only mammals that can fly, and they are extremely specialized for this skill. Their bodies have an aerodynamic shape, their bones are light, and their wings are thin, flexible, and hypersensitive. In fact, their wings have almost two dozen joints, and are covered with Merkel cells, which are the touch-sensitive cells found on our fingertips.

Unfortunately, most bats' rear legs are more or less useless for anything except hanging. They are very thin and weak with fragile bones. Their knees also face backwards. If a bat ends up on the ground, he'll use his front limbs to clumsily drag his body while keeping pressure off the back legs. This can be awkward, since the front limbs are meant for flying rather than crawling.

However, out of the over 1,200 species of bat, there are two species that actually can walk - the vampire bat and the burrowing bat (also known as the lesser short-tailed bat). In fact, a laboratory study using treadmills showed that vampire bats can even sprint on all fours. They primarily use their front limbs, and can even reach speeds of 2.7 miles per hour. That may not sound very fast to a jogger or power walker, but it's definitely respectable for a small animal that's more equipped for flight.

The burrowing bat has adaptations conducive to walking - claws at the base of their toes, grooves on their feet, and elbow joints that bend sideways and allow them to use their wrists to push off. Burrowing bats take advantage of these traits to forage for food on the ground as well as in the air.