When hiking, skiing or snowshoeing, you may see tiny black or dark blue snow fleas — or springtails. When large numbers of them are on the snow, it appears black or even blue and, more rarely, other colors, even white.

Q: Hi Thom, you probably told us about this already, but I missed it. On Tuesday, while hiking in Williamstown, we saw literally millions and millions of these little tiny black jumping dots everywhere. Can you please tell us about their life cycle? Do they hatch in trees and fall to the ground, or do they come up through the snow? How long do they live and what do they eat, and how do they reproduce?

— Sandy, Adams

A: Springtails are fun to watch, especially when you disturb them and they jump. They are champions in this regard. I must admit it has been a while since I have seen a good display and, as I recall, encounters with them occurred for me mostly in late winter with snowmelt. Maybe the term snowmelt is important here, allowing them to emerge from beneath leaf litter and soil — even during the winter or late fall during snowmelt.

These tiny black or dark blue snow fleas are better called springtails, as they are not fleas like we dread on our cats and dogs, but are arthropods in a group called Collembola, and unlike most insects, remain active throughout the winter.

I will answer your questions, although first, I want to explain how they can launch themselves a distance, many times their body length. Beneath their bodies is located a folded structure that springs downward, catapulting them into the air. In a blink of an eye, one is there, and next, it is gone. And when dozens of them decide, almost in unison, to launch about 1-foot distance, it is exciting to watch. They cannot fly, so instead, they catapult.

Springtails often collect around the base of a tree, where soil and leaf litter may be visible. When large numbers of them are on the snow, it appears black or even blue and, more rarely, other colors, even white.

So dear readers, especially on warmer, sunny days look for black or blue patches at the base of a tree, take the time to stoop down and take a close look; they will not hurt you. They are perfectly harmless. Individuals reach on average 2 to 3 millimeters, less than a 10th of an inch.

These are tremendously abundant creatures, even in our gardens. But it is when they gather on the brilliant white snow that they become so apparent.

Now to answer Sandy’s question as best I can: They live in soil and leaf litter and hatch there, not in trees, to my knowledge. And they do not come up through the snow, but from the soil often around the base of trees.

They feed on organic matter, such as decaying vegetation, including algae and fungi. They will continue to dine even in the winter, as they do not freeze even in subzero temperatures. They have glycerin-rich proteins in their bodies that prevent ice from forming within.

Their lifecycle is less complicated than insects. The eggs hatch into a small version of the adult, no larval or pupal stage. As they grow, they molt and do so throughout their lives. As for how long they live, it depends on if they die after a week or three years. You will find an informative (and perhaps more extensive than you asked for) description of their reproduction at collemboles.fr/en/morphology-and-physiology/66-reproduction-of-springtails.html.

Q: We have a small sunflower seed feeder, and it has been comical watching six to eight of these yellowish- and black-colored birds with big bills trying to wait their turn to get at the seeds. I need to get a bird book sometime. In the meantime, is there a safe place on the internet to identify birds, with good pictures?

— Eleanor, North Adams

A: There are two sites that I suggest: audubon.org/field-guide/bird, offered by The National Audubon Society, and allaboutbirds.org provided by Cornell Lab of Ornithology.

And while on the subject …

The new year is upon us and it is a perfect time for starting a “checklist” of the birds you see accidentally while out walking or while specifically looking for our feathered neighbors. Home feeder-watchers are welcome.

And the right way, especially for newbies finding themselves enthusiastic about the birds seen either at a backyard bird feeder or while walking, is to take a beginner’s primer.

Consider taking Cornell Lab of Ornithology's birding primer; it is free. If you have yet to make 2021 the year you take eBird Essentials, do so now. This free, self-paced course has step-by-step instructions and insider tips for eBird's most popular features. eBird Essentials makes eBirding faster, easier, and more fun. To enroll, visit academy.allaboutbirds.org.

For an introduction to the value of eBird go to: https://vimeo.com/289704751