Weekly Bird Report
1:51 pm
Wed April 23, 2014

Courtship Prompts Local Raptors to Unusual Sounds and Behavior

Osprey female
Credit Vern Laux
Raptors Noisy in Courtship Season, The Weekly Bird Report by Vern Laux

At this season the Cape and Island’s nesting species of raptors engage in courtship displays and behavior only seen a few weeks a year. Most amazing is the sounds that they make - since the birds are mostly silent for the rest of the year, it is a mild shock to hear what they sound like!

Diurnal raptors including Ospreys, Red-tailed Hawks, Cooper’s Hawks and Northern Harriers are all very obvious now. These species all breed in our area and the sights and sounds of their courting are hard to miss when the weather is not miserable. They know what time it is, even if the temperatures refuse to cooperate.

Red-tailed Hawks engage in spectacular aerial courtship displays accompanied by lots of screaming calls.  Courting pairs engage in leg dangling, talons dragging through the air, descending flights - and then rocket skyward again to perform spectacular loop-de-loops. These impressive diving flight displays have been a common sight when the weather has been good during the past weeks.

The moth-like, exaggerated deep wing beat, flights of displaying Cooper’s Hawks with calls have also been a regular feature all over the region. This behavior and manner of flight gives these fast flying predators, which specialize in ambushing other birds, an entirely different look from what one is used to.

Northern Harriers, raptors that specialize at capturing rodents with their very long legs, catching them by flying at a slow speed over open fields, dunes, and marshes, have the only significant breeding population in the state on the Cape and Islands. They are also engaging in their special courtship flights. Both the male and female engage in these flight displays. The individual performing the flight will climb vertically until, just as it is about to stall, it flips its body upside down and inverted falls back towards earth. Regaining flight control it gathers speed and as it gains speed it pulls back, climbs again, and repeats the whole process for the benefit of its watching partner. It is amazing to watch as the birds reach the top of their arc and flip over in the blink of an eye.         

Ubiquitous male Ospreys can be heard, even above downtown areas, as they engage in aerial flight displays involving a slowly ascending hover, usually with a fish in their talons, with lots very distinctive calling. Most female Ospreys are already incubating eggs. Their relatively high-pitched calls are seemingly at odds with these birds robust general impression. The birds arrived from wintering grounds and immediately set about repairing the nest, attracting or reaffirming pair-bonds with a mate, and even in some cases getting right to the business of making another batch of Ospreys.