Doug Hitchcox clears the leaves on about two-thirds of his yard, but leaves them on the rest to help provide cover for Isabella tiger moths, wood frogs and other insects and small animals. Doug Hitchcox photo

I have a question about the “leave the leaves” idea. I plan on leaving my leaves on the ground over winter. My question is about spring. When is it safe to begin cleaning up my yard? I would hate to leave my leaves on the ground over winter, helping foster various forms of insect and animal life, only to kill said life before it “hatches” by raking up the leaves or mowing my lawn too early.

— Allen Bailey, Farmington

The idea of “leaving the leaves” in your yard is intended to be a win-win for everyone and everything: Invertebrates and other wildlife that use leaves as shelter have a greater chance of surviving the winter. Nutrients are returned to the soil and weeds are suppressed. And it’s less work for you! Less carbon emissions too; as the EPA reports, “leaves and other yard debris” make up more than 13 percent of the nation’s solid waste, most of which gives off methane (a greenhouse gas). In your yard, this isn’t a problem because there is enough oxygen for the leaves to decompose.

But many of us still have a yearning for a perfectly mowed, typically non-native grass lawn. I recommend reading Krystal D’Costa’s 2017 Scientific American piece “The American Obsession with Lawns” for a breakdown of our weird fascination with this “symbol.” The unfortunate truth is that if you want a “perfect” lawn, you’re almost certainly going to have a negative impact on some wildlife.

Along with “leave the leaves,” consider the “less lawn” movement, which promotes reducing the amount of your yard that is lawn. Think about the space that you actually use. Could you stop mowing and primping the edges or spaces with virtually no foot traffic? In my small Windham yard, I’ve been planting natives and done no raking in about one-third of our yard, leaving it for the Isabella tiger moths and wood frogs I regretfully disturbed while leaf-blowing last year. And because of some strange societal pressures, the area of my yard right in front of my house is mowed lawn with leaves removed. No bees or salamanders stand a chance of surviving, but that curb appeal is on point.

Getting back to Allen’s question, the leaves that currently carpet my backyard (to be mowed next summer) will sit there until late spring. The goal is to leave the leaves until any of the critters living under them have emerged and become active. Justin Wheeler has written some great questions, for the Xerces Society for Invertebrate Conservation, that you can pose yourself in the spring: Have I put away my mittens? Have I paid my taxes? Would I plant tomatoes now? And have apples finished blooming? By the time you can answer all of these questions with a “yes,” you’ll probably also be seeing bees flying during the day and moths at night, and hear frogs calling in the evening, a rewarding indicator that you did the right thing.

A CURIOUS WAY TO SAVE ENERGY

As I was walking on the beach recently, I was photographing what looked like sanderlings. A small portion of these birds only have one leg – or at least that’s how it appeared. I am not a birder, but I am concerned that some environmental process is in play. Just thought I would inform you.

— Denise Wood, Old Orchard Beach

Sanderlings on a sandy beach, chasing the waves, is a sight Mainers near the coast can probably envision. The tourists are gone and these small white shorebirds are about to spend the winter in Maine. While most shorebirds migrate through Maine, we have four species that will overwinter here, with sanderlings being the most common. In order to survive Maine’s winter, these birds need to use a variety of adaptations primarily around conserving energy, and one of the most commonly observed is standing on one leg. So there is an environmental process at play, just not the one Denise was worried about!

Standing on one leg takes half the energy as two. It is very common for sanderlings to stay on that one leg, and hop away from waves or approaching beachwalkers, rather than put it down to move. They can even take flight from that monopod. Not only does it take less energy to stand on one foot, it also conserves energy by limiting heat loss. Humans are terribly inefficient at retaining heat through our blood flow, as our arteries carry warm blood away from the heart, the blood cools, then is sent back to the heart via our veins to be rewarmed (and oxygenated). Birds have an amazing anatomical adaptation known as “rete mirabile” in which their arteries and veins are closer to one another, more interwoven, which helps regulate their temperature better. We can also think of keeping that leg tucked in its insulating feathers, against its warm body, as cutting its heat loss in half.

Of course, not all birds are perfectly adapted for surviving the cold. The great black hawk, a tropical hawk that graced Portland’s Deering Oaks Park exactly two years ago (Nov. 29, 2018), eventually succumbed to the cold and was found to have frostbite. While unfortunate, these injuries are not unheard of even in common species: looking closely at the birds at your feeders in the winter, you might see one or two locals missing digits or tips of toes, apparently from frostbite. The important takeaway here is that birds are very well adapted to survive Maine’s variable climates, but we can increase their chances by doing things to limit the energy they need to expend. In the case of shorebirds, keeping dogs on a leash and giving birds space so they don’t flush can result in saving energy that could mean life or death.

Do you have a nature question for Doug? Email questions to [email protected] and visit maineaudubon.org to learn more about virtual and backyard birding, online classes and other programs about wildlife and habitat.


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