Once temperatures reach the 80s and 90s, tiger beetles are more likely to shelter. Doug Hitchcox photo
By far the most common question we get at Maine Audubon is “Where are the birds?”
This is always an interesting question, because there are varying factors throughout the year – and even between different years – that will affect the birds you are seeing or hearing around you. For instance, as the nesting season wraps up, many birds aren’t singing anymore, and there is an abundance of naturally occurring food right now, so birds are really hard to detect. This year, we’ve also been getting a lot of inquiries about insects, as in: “Where are the bugs?!” So let’s take a look at some of the factors influencing our six-legged friends.
First, we have to acknowledge how the weather can affect insects. This has been a summer of extremes. By the time you’ve gotten to this section of the paper, you’ve probably passed headlines about “longest heat waves” or “flash flood warnings,” and the weather can play a big role in insect activity. Let’s also acknowledge that insects are a hugely diverse group, and while some conditions may be detrimental for certain species, they can also have no effect or even favor others. The same is true of the food that they eat, and it’s important to consider the need for a robust food web in keeping our insect diversity strong.
The heat can often help insects by speeding up their metabolism and, in particular, can make parts of their life cycles go much quicker (think: the time it takes for eggs to hatch into larvae). On the flip side, when it is too hot, some insects need to protect themselves and will be less active. Anecdotally, I’ve been searching out tiger beetles (cicindelinae) this summer, and it has been interesting to watch their behaviors based on the ambient temperature. They’ve been most active and easy to find when it gets over 70 degrees, but once we are in the 80s and pushing 90s, they’ll shelter much more, burrowing underground or finding vegetation to stay in the shadows. They’ll even sit in a position called “sun facing” (as the name suggests, they’re facing directly toward the sun), which minimizes the amount of surface area of their bodies in the direct sun, all making them harder for me to find!
Another interesting thing to consider is observer bias. As individuals, it is really hard for us to get a good understanding of what is happening with wildlife, as we’re often not getting a large enough sample size, or covering a large enough area. There are different larger, even global, citizen science projects to which folks can contribute their individual sightings so we can study this, but unfortunately there isn’t a great one that looks at observer effort and insect numbers.
So instead, I took a look at eBird, a project by the Cornell Lab of Ornithology for people to submit their observations of birds, as a baseline to see how people’s effort, or time in the field, has changed this summer. Interestingly, while the number of checklists submitted every year in Maine has grown by about 20 percent, the last two months have seen huge drops. Over June and July, each week the number of checklists submitted in Maine was down an average of 30 percent compared to the same week last year. If we can use this as a sample of “people spending time outside observing nature,” then we’ve clearly seen a huge drop in the amount of effort over the past two very hot, and/or very wet, months.
It is important to be aware that we are seeing significant population declines across our insects on long-term scales. Some of our short-term observations may be because of how the weather is affecting both them and us!
BIRDS IN THE GULF OF MAINE
Along with the warm weather we’ve been experiencing, the water temperature in the Gulf of Maine has also been warm, yet again, this summer. We’re all hopefully aware that the Gulf of Maine is warming faster than 97% of the world’s ocean surfaces, and this often leads to some interesting observations, as we are on the front line for how these changes affect the animals that use the gulf. Since I’ve had a number of conversations with folks about this lately, I wanted to share some information with you here.
The ocean temperature can play a huge role in the types fish and birds we see in the Gulf of Maine. During some of the worst nesting seasons for puffins, these small birds usually see high mortality rates because of the types of fish that come up with warm water. Species like butterfish are too large for puffin chicks to be able to eat, so despite the abundance of food, chicks will often starve.
There are also seabirds that are temperature sensitive. Some species stick to the warm waters of the Gulf Stream, like black-capped petrel, a species yet to be found in Maine, but one we perhaps will soon be seeing, given the trends in Gulf temperatures. This summer has had some bizarre seabird sightings in the Gulf of Maine, first with a yellow-nosed albatross spotted on a whale watch out of Boothbay. This species should be in the south Atlantic (think: Tropic of Capricorn) but has actually been recorded at least seven times in the Gulf of Maine before this. Another noteworthy sighting was a red-footed booby, found resting on Marlboro Beach in Lamoine, the first time this species has been seen in Maine. It does make you wonder what causes such birds to show up here. Is it the weather, or food they’re following, or is word spreading that Maine is the best place to spend the summer?
In closing, I encourage you to get out on the water in the next couple of months, if you can, and see these things for yourself. We often say that pelagic (offshore) birding is the final frontier, and you never know what you might encounter. Later this month, I’ll be joining the Cobscook Institute’s Downeast Migration Birding Festival with multiple boat trips out of Eastport, plus walks on the mainland for folks interested in those. And Maine Audubon’s annual pelagic trip out of Bar Harbor is set for Sept. 16. We’ll look for birds and any sea life on the Bar Harbor Whale Watch’s large jet-powered catamaran, by far the best platform we know of!
Do you have a nature question for Doug? Email questions to ask@maineaudubon.org and visit maineaudubon.org to learn more about birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug and other naturalists lead free bird walks on Thursday mornings, 7 to 9 a.m., at the Gilsland Farm Audubon Sanctuary in Falmouth.
Send questions/comments to the editors.
