A monarch butterfly at the Gilsland Farm Audubon Center in Falmouth. Ariana van den Akker photo

Monarch butterflies are on the wing and coming into Maine for the summer. With each one I’ve seen on a walk lately, the sighting is followed by someone asking, “Doesn’t that seem early?” or “It feels like they’re late this year.”

A monarch’s phenology is a bit more complicated than most animals we see in Maine. It’s not like a typical migrant that spends the winter to our south, comes north to breed, then returns south. Monarchs take several generations each year just to reach the northern breeding areas. Then the final brood is the one to make the long trek south. The monarchs that we see in Maine will be heading to Mexico for the winter.

A major concern that people have been expressing about monarchs this summer is the timing of their arrival in relation to their host plant, milkweed. Keep in mind that all butterflies (and moths, and most insects) rely on just a few species of plants that are “hosts” to their eggs. These hosts are the only plants that the freshly hatched larvae (caterpillars) are going to be able to eat – others are toxic to the caterpillars. So, because monarchs need milkweed, a common concern is the mismatched timing between the arrival of monarchs and the blooming of milkweed.

This brings us to an important distinction – the monarch needs the leaves of the milkweed for its larvae to feed on (not the blooms), while the adults can nectar on any nectar-producing flowers. Even if the flowers are barely open, or have passed quickly in the heat, monarchs have an amazing variety of sensors, including their antennae and chemoreceptors on their legs, that allow them to detect and even test the plants they are encountering.

The question of “too early” or “feels late” is tricky because there are so many environmental factors that can affect the timing of when monarchs make it to Maine. Was it a warm spring? Were there any storms delaying them? Since it usually takes three broods (adults laying eggs, those eggs hatching, pupating, and becoming adults that move farther north) to reach Maine, that long list of variables can be compounded to make individuals either early or late.

The Maine Butterfly Survey has some great charts that show “flight periods” of all of Maine’s butterflies. For monarchs, there is a peak in late July, which is likely the arrival of that year’s third brood, then sightings continue to ramp up, hitting its highest point in early September, as the fourth brood takes to the wing and begins the long migration south.

All that is to say we needn’t worry; milkweed blooming doesn’t need to be in sync with monarch arrival. The best thing we can do is make sure monarchs have ample supplies of both nectar-producing plants and standing milkweed (and its leaves) when they are ready for it.

BATTLE AT THE BIRD FEEDERS

Putting out bird food in the summer can lead to some pretty entertaining observations. One important factor that determines which species will be at your feeder and when is their breeding stages. When birds are nesting, the food they really need is in the form of nutrient-rich invertebrates, aka insects. Baby birds need insects by the mouthful to develop and be able to fledge. But once they’ve left the nest, juveniles can be found hanging around bird feeders, especially following their parents there as they learn to forage.

This tees up a recent question sent in from Karen Gersen, who noticed that blackbirds have totally taken over her feeders and have chased away the finches and smaller birds. She says, “The blackbirds are really too big for the feeders but they are determined to rule the roost.” I often hear from people observing large flocks of blackbirds, especially common grackles, early in the spring migration, but once those birds start breeding, the flocks dissipate as individuals are busy maintaining their territories and raising their young.

Fast forward a few weeks, and once those baby grackles have left the nest, they will follow the adults around, begging for food. A bird feeder, especially with fruit or suet, will be quite appealing to a blackbird with a couple of squawking mouths in tow. As Karen observed, her yard was “complete with screaming, screeching and pushing!”

This may seem a bit unruly, but it is wonderful to be able to see when birds are successful nesters. Beyond the pushy grackles, you can also keep an eye out for baby woodpeckers, cardinals, and even smaller birds like chickadees and nuthatches. It’s tricky to exclude the larger birds from feeders, but one trick is to use an adjustable cover that can be lowered to make it harder for bigger birds to access the food. With that in mind, you can try different feeders, like some tube feeders with small perches, to encourage the birds that you want to be watching in your yard.

MYSTERIOUS SONGBIRD ILLNESS

Many people are asking about the illness that is affecting some songbirds in the mid-Atlantic states, causing blindness and even death. So far, this illness has not been seen north of Pennsylvania. At this time, it’s still safe to keep your birdfeeders out, though it’s always best practice to clean them regularly.

Do you have a nature question for Doug? Email questions to [email protected] and visit maineaudubon.org to learn more about bird walks, community science projects, and other programs about wildlife and habitat.


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