COLUMN: Nighthawk screech means insects on the menu

Recently an unexpected screechy sound and jet engine-like swoosh disturbed my early night.

Recently an unexpected screechy sound and jet engine-like swoosh disturbed my early night.Dianne Bersea

Repeated at short intervals and even intensified by other shrieks and swooshes, the sound quickly drew me outside.

A small crew of dark bird shapes swooped and dove overhead in the waning light.

Occasionally the white under-wing patches caught the light for a dazzling display accompanied by that persistent and rather uncharming call.

These busy birds have often been part of my evenings, and, when I rise early enough, part of my mornings too.

I first noticed them on a Garibaldi Park hike back in the early 1970s. There they were swooping and diving silhouetted against the mountain peaks and pale evening sky.

They were also a big part of my camp cook mornings when I had to be up before dawn on a Nicola Valley archaeology project. How nice to hear and see them in the Okanagan too.

Known to me as mosquito hawks, these birds are actually Common Nighthawks. Though hawk in name only, they’re a nocturnal insect eater of the Nightjar family.

As the more commonly visible of this group, the Nighthawk is a mid-sized bird with a smallish body dwarfed by aerodynamic wings that can span 60 centimetres (24 inches). Known for one of the longer bird migrations, they winter in South America and return to North America and into Canada for our warmer months.

Moments ago, I popped out again into a showery, dusky evening to see their aerial display. I’m not disappointed.

At first I can only hear their cry, a “zzzreep, zzzreep”, also described as a “beeent, beeent” sound. How does a person describe that unusual noise?

I also hear the booming, swooshing call of the males as they plunge earthward and pull out in a dramatic turn that marks their summer breeding season.

Their intense call is hard to miss even if you spend just 10 minutes outside in their flying time, usually about an hour before and after sunrise and sunset.

In flight they’re hard to keep track of with their short glides, quick wing beats and abrupt direction changes. They can swoop to within a few feet of the ground or chase insect prey to considerable heights.

But they disappear when they’re on the ground or roosting horizontal on a branch.

Their mottled pattern of brownie-beige with speckled lighter and darker tones is good camouflage.

Trusting their disguise means they don’t build a nest but simply lay their eggs directly on the similarly coloured ground. I’ve yet to see a Nighthawk there, or in a tree — and I’m looking!

But I’m thrilled that these bug decimators choose to visit on the wing. This speedy bird is a serious ally in pest control.

They dine voraciously on our most problematic insect pests — flying ants, beetles of every description, moths, grasshoppers, flies, mayflies and the dreaded mosquito!

Although small beaked, Nighthawks have a cavernous mouth that when open wide can scoop dozens of insects from the air.

Look for them around outdoor lighting that attracts clouds of insects. Nighthawks mop-up them up!

Thankfully, these helpful birds remain fairly common compared to other members of their family, but in some areas they are noticeably less common than they were.

Declining numbers are likely due to the usual suspects: habitat loss, pesticides and reduced prey. As we wipe out insects that threaten our crops by using chemical pesticides, we also lose the insect’s natural predators like the Nighthawk.

We seem to be on this complex treadmill a lot these days. We solve one problem only to create another.

I wish I knew the solution. But in the meantime I make a point of enjoying the evening and early morning Nighthawk chorus. Their song is not melodious but it tells me they’re on the job, and I’m pleased about that.

Dianne Bersea, a member of the South Okanagan Naturalists Club, is subbing for Bob Handfield who returns in August.

The opinions expressed here are those of the writer and do not necessarily reflect SONC. For information on SONC meetings, speakers and events visit southokanagannature.com.