Nesting begins - Barred Owls!

Monday, Mar 3rd:

6:15 PM, Temperature: 11 C (51 F)

I first saw the Barred owl (Strix varia) in late January when it arrived right outside my office window in the early evening with its characteristic call - "hoo, hoo, too-HOO; hoo, hoo, too-HOO, ooo" which is sometimes translated as - "Who, cooks, for-you? Who, cooks, for-you, all?". I had never seen a Barred owl before and it was an exciting moment for me! Since then, I’ve seen two birds – the first one I saw is a fine specimen (see pictures) with exquisite plumage, and the other, a more dull bird, has a slightly disheveled appearance. I’m uncertain about the gender of each bird, but I’m tempted to assign the more beautiful bird (which also appears a bit larger) as the female. Reverse sexual dimorphism (females larger than males) is common among raptors and is generally the case with Barred owls^1,2. The owls seem to start their day (night, for us) rather early and I’ve seen them frequent the area around the pond as early as 3:00 pm! On most occasions they appear to be roosting while sometimes the ‘female’ will attempt to make a catch among the numerous squirrels foraging on the forest floor.

Earlier today (~4:30 pm), I had seen one of the owls being harassed by a group of crows near the pond. The owl had then flown towards the bridge and was hidden from view in a tangle of branches.

But, around 6:15 pm, a little after sunset, I heard both owls call nearby and saw one of the birds fly towards the other. Both met among the tops of the thin ___ trees and made contact for a few seconds. It was too dark and it was hard to tell if they actually mated or if it was part of a courtship interaction. It happened again in the same manner within the next minute and then both birds flew north towards the road. I heard their calls through the later evening, and I thought, perhaps they’re mating and will have a nest/hollow in the vicinity.

Tuesday, Mar 4th:

4:00 PM, Temperature: 15 C (59 F)

I was talking to a colleague in my office when suddenly I heard loud calls of the Red-shouldered hawk uttered in a sharp manner and in rapid succession. They sounded harsher than the usual drawn out keeeaah. This time they sounded more abrupt and I immediately suspected something was wrong. The hawk sounded alarmed!

I rushed to the window and instead of seeing the hawk I saw the Barred owl perched low near the tulip tree. Then I saw some movement nearby and it was the hawk! For a moment, I was confused – what is this trick? Am I seeing an owl or two hawks?

Then it occurred to me – The hawk was probably flying over and had spotted the owl as it was starting its day. It was obvious that the hawk did not like what it saw. It was evidently quite agitated with the owl perched within a hundred meters of its new nesting site. Barred owls and Red-shouldered hawks are known to nest within each others territories without apparent conflict¹. They are both usually active at very different times of day and that keeps them out of each others way. But, our owls are early risers – sometimes active more than two hours before sunset. This is one of the ideal times for the hawks to be hunting as well. They are very similar sized birds, but the hawk was clearly more aggressive in this situation. Its calls had a determined tone. The message to the owl was clear – you are in my territory and you are not welcome!

The owl retreated to the northern side of the bridge, gave a few low hoots and was gone. The hawk still calling, decided to hang around for a while and hunt from its low perch. Soon, it swooped low and picked up a small rodent then flew towards the pond. From there it again dived low near the fence behind Olin hall and caught another snack, before flying north into the park.

¹ Johnsgard, Paul A. (1988) - North American owls: biology and natural history. Smithsonian.

² Earhart C. M. and Johnson, N. K. (1970) - Size dimorphism and food habits in North American owls. The Condor, Vol. 72, p 251-264.