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Wolf Spider

October 31, 2008

Wolf Spiders are hairy hunting spiders in the worldwide family Lycosidae (Lykos is Greek for "wolf"), and these common spiders can be found in a wide variety of habitats. Although Wolf Spiders can be of any size, many of them are quite large, up to 1 1/3 inches (3.4 cm) long or more. Large Wolf Spiders are very common here in the Sonoran Desert, where they are sometimes mistaken for some of our other large spiders like Giant Crab Spiders (Olios spp.) or Tarantulas (Family Theraphosidae). I observed this large female Wolf Spider on the outside of my house one summer evening here in Tucson, Arizona.

Mother Wolf Spider (Family Lycosidae) with baby spiderlings on her back

The furry lumps on this spider's abdomen are actually her many spiderlings (baby spiders). A female Wolf Spider will wrap her eggs in a silken cocoon and then carry it around with her until the eggs hatch. The newly hatched spiderlings will then climb onto their mother's back and ride around for a short period until they either climb or fall off and are dispersed.

Wolf Spiders are typically cryptically patterned in a brown or gray color with a lighter-colored stripe down their cephalothorax (head and thorax). They have eight eyes in rows of 4, 2, and 2 and large, fang-like mouthparts called chelicerae that they use to masticate (chew up) their prey as they feed.

Wolf Spiders feed on other invertebrates, and except for Funnel-Web Wolf Spiders (Subfamily Hippasinae), they do not build webs. Instead, Wolf Spiders are active, fast-moving, visual hunters and will stalk, ambush, and chase their invertebrate prey. Wolf Spiders are nocturnal predators and have excellent nighttime vision due to the light-reflecting crystalline tapetum layer in their large eyes. This light-reflecting layer gives them a whitish blue or green eyeshine, which you may be able to see at night if you crouch down and shine your flashlight across a patch of grass or fallen leaves.

Although some can grow to an alarming size and are occasionally found inside houses, Wolf Spiders are not poisonous or aggressive towards humans, but they may bite if handled. Wolf Spiders generally flee from humans, but I did once have a huge one crawl up my pant leg (shudder) as I sat watching television. Thankfully, the Wolf Spider didn't bite me when I flicked it off, and as I ran shrieking from the room, I saw the equally terrified spider galloping off in the other direction. I have arachnophobia, and this sort of thing is the stuff of nightmares for someone like me. Despite this one bad experience, I try never to kill Wolf Spiders, especially the large ones, because they are highly beneficial in helping control filthy and annoying insect pests like cockroaches.

Red-billed Pigeon

October 27, 2008

Red-billed Pigeons (Patagioenas flavirostris, formerly Columba flavirostris) are tropical pigeons found in woodland areas from southern Texas to Costa Rica. In May of 2007, we spotted several Red-billed Pigeons in a palm tree in Alajuela, Costa Rica. We first heard their "Cooc cu cu coooo!" calls coming from the palm tree and then easily spotted these large, conspicuous pigeons.

Red-billed Pigeon (Patagioenas flavirostris)

Adult Red-billed Pigeons have a dull, reddish purple head, breast, and shoulders, a slate gray belly, rump, tail, and wings, magenta legs, orange eyes with a red eye-ring, and a distinctive yellowish white bill with a pinkish red base and cere. The sexes are similar, but the males are a bit more richly wine-colored. Unlike these pigeons with their white and red bicolored bills, other similarly colored species of pigeon like the Ruddy Pigeon (P. subvinacea), the Short-billed Pigeon (P. nigrirostris), and the Pale-vented Pigeon (P. cayennensis) all have dark bills. Young Red-billed Pigeons are more dully colored and have dark eyes and a dark bill.

Adult and immature Red-billed Pigeons (Patagioenas flavirostris)

Red-billed Pigeons typically nest in palm trees in open woodland areas. The females will lay only a single egg in their loosely constructed stick nests. Red-billed Pigeons feed mainly on fruits, nuts, and seeds, which are all generally plentiful in the open woodlands and agricultural areas of Costa Rica.