Each year I receive a number of phone calls or inquires from people worried about the lack of birds at their feeders in the summer time. Fear not! This is generally a good thing. Below, I’ll use some eBird data to illustrate some of the changes in a bird’s frequency or abundance throughout the year.
The first bird example we can use is the American Redstart. This migratory warbler spends our winter around Central America and the West Indies, arriving back in Maine during early May. Looking at the line graph below, you can see this peak – those returning birds (the males in particular) are staking out breeding territories that they’ll sing loudly around to defend and also attract mates. This abundance of migrants and singing birds makes for the highest peak in frequency, measured as the percentage of all checklists reported to eBird that include the target species (American Redstart) on it. Frequency drops into early June as migrants funnel through but the drop continues into July as nesting birds become inconspicuous. Those loud males are done finding mates and no longer need to defend their turf (as much) after their chicks fledge. And that is where we are now, in late July in Maine, and why it seems like so many birds are “not around”. Rather than being “gone” they are just doing a better job going undetected. You can see a second hump in the fall (Aug-Sep) as migrants pass through and numbers will increase with all of this year’s young about.
For another example, we can look at a nonmigratory species: Black-capped Chickadee. This is a fun example because the fluctuation in frequency is mostly driven by how conspicuous the bird is acting rather than the numbers of the species that are actually around (like with migratory species). So, referring to the frequency chart below, you can see a first spike in Feb – this is likely an artifact of one of eBird’s largest events, the Great Backyard Bird Count, which encourages backyard birders to submit the birds visiting their yards (and other places they bird). Otherwise you can see the spring peak as more birds are singing and becoming more detectable. Then comes the dramatic drop in June and July (notice that the scale bottoms out around 30% rather than 0% in the redstart example) while these birds are nesting and trying not to be noticed. This is also when activity drops at your bird feeders. The important thing to remember is that most of our nesting birds need protein, especially in the form of native invertebrates (Lepidoptera larvae), to feed their young. Bird seed is not a suitable substitute, though it may still help the adults. And as those chicks fledge, and more birds are eating seeds, you see the frequency increasing into the fall.
As a final example, I’ve had a lot of people asking about a decrease in Ruby-throated Hummingbirds in their yards. It can be harder to measure a species decrease in a single year, especially with such localized reporting, but let’s take a look at what eBird can show us: The chart below shows the “average count” of Ruby-throated Hummingbirds, comparing the past five years (2013-2017) but notice that we only have 2017 data through July. 2017 seems about on par with past years through mid-May then tends to be a bit below average. It is easy to assume that hummingbirds are having a “tough” year given how cold the spring was but I don’t see any reason to assume any thing is terribly wrong with our hummingbirds. You can click on the cart to access it in eBird and then view frequency to see how their fall “peak” is coming – so if you aren’t seeing many hummingbirds right now then you should be in a couple weeks (mid August is peak frequency in most years). I should point out that I used “Average Count” rather than “Abundance” to illustrate this point because “Average Count” only looks at checklists including the target species so it depicts how many of that species are expected when encountered, rather than “Abundance” which shows that species compared to all other species in the region.
The point I want to emphasize here is:
Seeing fewer birds at your feeders in the summer is probably a good thing! The reason so many birds come to Maine to breed is because of the abundance of natural food. I will always advocate for people to keep feeding birds – it is a great window that makes the natural world so much more accessible in a time where we are becoming more and more disconnected with the changes around us. So, along with your bird feeder, why not plant an oak tree that will support hundreds of caterpillars that will feed the baby birds starting the next generation of these winged wonders we so enjoy!