Backyard Nature: Some delights of nature to look for as summer slides into fall

Chinese chestnut tree

by Marjorie Rachlin

In September I make a trip to Rock Creek Park to see how the Chinese chestnut trees are doing. These trees were planted nearly a hundred years ago, after the chestnut blight had decimated our native chestnuts. As you can see from the photo, they have a bountiful crop of prickly chestnut burrs this year. Each burr contains four chestnuts – the seeds.

Seeds are the name of the game for many trees and plants. All summer they have been pouring resources and energy into seed production. It’s their future – winter is coming, and seeds are needed to ensure a new generation in the spring.

These are the pods of common pink milkweed, growing in local meadows. They tell us something else about seeds. Nature is prodigal – she makes many more seeds than can possibly germinate. Although this pod contains over a hundred seeds, most of them will be eaten or fall on barren sites.

I can see this happen with the red lobelia (cardinal flower) in the garden. The lobelia blooms all summer, making the small seed pods you see along the stem. Each pod contains hundreds of tiny seeds the size of poppy seeds. I cast more than a thousand seeds all over the garden, hoping for more lobelias next year. I feel lucky if I find five or six new plants next May.

Seeds are a way that nature provides a food supply for animals and insects. We have all watched squirrels and chipmunks storing acorns, and goldfinches eating thistle seeds in Broad Branch Park. Seeds of native grasses sustain insects and birds. Recently, I was puzzled to see a squirrel sitting in a Japanese maple tree for an hour. Then I discovered it was eating the tiny winged maple seeds.

Birds on the move

Black-throated green warbler, one of 15 fall warblers that may be seen in DC (photo by Dick Rowe)

All over the northern hemispheres, birds are moving south. August and September are prime time for warblers to drop into Rock Creek Park, and the local birders are up at 6:30 a.m. to welcome them. The hawk watchers here and at Cape May are busy counting hawks and ospreys – in October it will be eagles.

The hummingbird in my backyard left on September 18th. It was visiting the feeder and the garden flowers five or six times a day during the last month. It is either a female or an immature male – it does not have the mature male’s ruby throat.

These frequent visits build resources for the long migration flight. Most hummingbirds take a perilous route – first stopping in Florida, then flying non-stop over the Caribbean to South America. Many birds die during migration, particularly the immature ones doing it for the first time. I hope my visitor makes it.

Insects Prepare for the Cold

On warm days, you can hear the cicadas making a racket, anxious to get a mate and reproduce. The cicada in the video has been the unlucky prey of a cicada-killing wasp. The wasp stings repeatedly with a chemical that paralyzes the insect, but does not kill it.

The female wasp wants this cicada as provision for her offspring. She will drag the carcass to her nest (usually in the ground), lay an egg on it, seal the nest and leave. When the egg hatches, the larva will find its breakfast all ready.

The caterpillar in this photo is a monarch. I was delighted to find seven of them eating the leaves of the orange milkweed that grows by the curb. But in a few days bird predation or weather took a toll and left just one.

It is getting toward the time when monarchs migrate south to Mexico for the winter. In the fall, the females do not lay eggs – they are programmed to start the journey south. There will be no more caterpillars. Both males and females migrate – the hawk watch at Cape May sees thousands. Next spring the monarchs in Mexico will leave their hibernating roost and start north. After about 200 miles they will reproduce and produce a new generation that will make another jump north. The third or fourth generation will reach DC in July.

Many species of butterflies, bees, spiders, and other insects lay eggs that will over-winter and hopefully hatch in the spring. They hide them in bark, leaves, walls, logs, nest holes in the ground and other secluded spaces. Once the eggs are laid, the adults usually die, their mission accomplished.

Resident Toads, Snakes and Turtles

Our local small “critters” are enjoying fall’s bounty. They are eating fruit, insects, mushrooms, berries, snails, slugs, frogs and plants. They will hibernate when it gets colder.

The young American toad in the photo was seen in woodlands, but you will often find one in your garden. This toad species lives on land, and looks for water only in the spring mating season. Forest Hills has many lily ponds and wet depressions, so you have probably heard American toads trilling during spring evenings.

This one started life last spring as a tadpole. Now it is about one and a half inches long.

We expect to find turtles in water, but box turtles live on land. This one, found near a trail in Rock Creek, is about 15 years old. It will hibernate over the winter. Please don’t touch it or pick it up. It is probably too young to lay eggs – a mature female would dig a hole in the ground in May and lay four to seven eggs.

I never run across snakes in Rock Creek Park, probably because I am a noisy hiker and they hear me coming. Snakes are not anxious to see us – they hide or freeze.

The photo shows a northern water snake, which the resource manager of Rock Creek Park tells me is common along creek banks. It is one of twelve species of snake seen in the Park. None of them are poisonous.

Coming Up

I’m looking forward to the weeks ahead. Lovely fall weather and much to watch as the leaves turn and nature changes. Don’t miss it.

Thanks to Marlene Berlin, Eric Kravetz, Dick Rowe and my aide Aissatou Diallo for the photos.