I'm an avid birder and nature photographer wishing to share some of my sightings & images taken while out in the "wilds" of Cape Ann and surrounding New England countryside. More images can be found on my web site at New England Birds Plus Enjoy, Phil Brown

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Friday, November 11, 2011

Screech Owl Color Morphs

Screech Owl Color Morphs in Eastern Massachusetts, a very unscientific look.

Richard Pegler of the UK and founder of The Owlers’ Blog http://owlersblognetwork.blogspot.com/ gave me a poke recently asking what the breakdown was for red and gray Screech Owls, more red, more gray, in eastern Massachusetts? I’ve pulled together information from a couple of sources to try and answer the question.

The Birds of North America, a wonderful (subscription required) online resource that I use on a regular basis and available at: http://bna.birds.cornell.edu/bna states “ No other North American owl has such distinctive plumage differences” and “Fluctuating morph ratios represent balanced dimorphism during warm-wet (rufous more frequent), cold-dry (rufous less frequent) climatic cycles”.

For an unscientific look at the question, I’ve used Birder’s Diary http://www.birdersdiary.com/ to track my bird sightings for the past 11 years and have pulled my data together for Eastern Screech Owls. 

As of Nov 09, 2011 I’ve recorded a total of 589 Screech Owl sightings. Of these I noted the color morph on 513 of the sightings of which 370 or 72% were red - 124 or 24% were gray and 19 or 4% were brown. 

A number of my sightings are of the same birds over several days so the data is a bit biased but I'd say the red morph is the most common in eastern Massachusetts.

Another feature within Birder’s Diary allows you to create “Abundance Charts” tracking my sightings on a bar graph through a year’s time as seen below.

 This really tells the story for my sightings of Screech Owls, plenty in the late fall, winter & early spring and next to non in the summer months. I’ve seen very few young Screech Owls, with one look at a family group when I was around 12 years old over the house at the old homestead in Wenham, another when I was asked to rescue an owlet that decided to sit on a homeowners lawn after fledging (I got there before the cats did) and photos of a youngster sitting in the nest hole a few years back in Rowley as seen below.

 With the addition of several nest boxes in the area I’m hoping to change my luck with Screech Owl sightings in the summer months. Time will tell!