Docent Circle: Field Notes Week of 2005-05-15

Watch for the appearance of the tiny crab spider this month. Typical crab spiders are predators that lie in wait to feast on their prey. You fill find it inside flower heads busily ambushing flies, bees, and butterflies. This spider builds no web and changes its color to match whatever flower it is visiting. Though their chelicerae, or jaws, are rather small and slender, many crab spiders possess potent venoms that quickly immobilize their prey. Flower spiders, a particular type of crab spider, rest on flowers and remain motionless for long periods of time with their front two pairs of legs extended in readiness.

In keeping with their ambush style of attack, many crab spiders are well camouflaged, blending in with their backgrounds. Some of the flower spiders are able to change their color over several days, typically between white and yellow, depending on the color of the flower on which they are resting. Some resemble tree bark, leaves, or fruits; others appear to mimic bird droppings. Their venoms enable them to successfully attack insects much larger than themselves. They do not wrap their prey in silk after biting, but instead remain with the immobilized prey until they have sucked it dry.

Consider encouraging your students to go on a treasure hunt to find a crab spider - they will relish the facts you can give them when they find one of these spiders lying in wait, hidden in the folds of the flower.

Songbird Foraging is one of the most frequent behavior birders encounter - and one of the most interesting. Different birds go about it in different ways. A Black Phoebe can provide many minutes of entertainment as it sallies from a perch and snatches up bugs mid-air.

Warblers seem always on the move as they glean insects from foliage and bark - and take on added interest when one realizes that different species tend to search in somewhat different places. Chickadees and bushtits scramble through trees, often in flocks, frequently hanging upside down to search out an insect morsel. Swallows zoom along acting as speedy insect nets ungulfing "aerial plankton" - small flying insects.

Towhees and fox sparrows use both feet simultaneously to scratch up litter and uncover edible items; thrashers sweep and dig with their bills for the same purpose. Thrushes run along the ground, pause, and pounce on insects or earthworms. Meadowlarks walk along bobbing their heads and spearing their prey. You may observe bluebirds hovering before dropping on prey on the ground.

A given species of bird will often change its foraging behavior from area to area depending on the kinds of food items that are available. Watching and recording patterns of foraging can be a fascinating and useful activity - one that you can encourage your students to pursue and question.

Awaken Enthusiasm ~ Focus Attention ~ Direct Experience ~ Share Inspiration
From: Sharing Nature with Children by Joseph Cornell

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