Petrochelidon pyrrhonota

At the State Park the other day, I amazed and delighted a group of toddlers by pointing out the cliff swallow nests under the eaves of the restrooms.

The cliff swallow is among North America’s most social landbirds. They often nest in large colonies, with a single site sometimes hosting several thousand active nests. Their nests are made from sticky clay, which can endure for years, and the birds’ tier-stacking building technique helps support them. Swallows from the same colony cooperate in nest building: they gather mud together in small areas and then return to their nests carrying clumps in their bills. They preen, feed, drink, and bathe in groups, and they continue sticking together in large flocks during migration and on their wintering grounds. 

thigmotropism

Thigmotropism occurs due to unilateral growth inhibition. In twining and tendrilled plants, the growth rate on the side which is being touched is slower than on the side opposite the touch. The resultant growth pattern is to curl around the object which is touching the plant.

Roots also rely on touch to navigate their way through the soil. Generally, roots have a negative touch response, meaning when they feel an object, they grow away from it. This allows the roots to go through the soil with minimum resistance. Because of this behavior, roots are said to be negatively thigmotropic.

I’m tucking this new word into my vocabulary pocket for a future scrabble game.