It’s all in the i-Details Birds in Black
I have never used the very popular Merlin app for bird identification. As mentioned in an earlier blog, I cut my teeth as a birdwatcher using descriptions found in hard copy field guides, so old habits die hard. I even carry a Sibley’s guide book in my car. But, I’d like to test out Merlin’s skills with two species of black birds found in the London area. Not blackbirds as in Red-wings, but larger all black birds in the corvid group that look strikingly similar - the American Crow and Common Raven.
When I first moved to London about 6 years ago, ravens were an uncommon sight in this area. I remember driving out to the furthest corner of NW Middlesex county to search for that hard-to-get tick on my local bird species list. The ravens I saw seemed to be associated with old silos, perhaps as good sites for nesting. Over the past few years, their reports have become more frequent on eBird. A few birders have seen them in airspace over some of London’s ESAs but generally ravens are more likely to be soaring above rural lands and crows are the birds-in-black across country and city.
With only a passing glance, that very obvious colour similarity between the two species makes them look the same. Closer observation and a bit more viewing experience reveals some subtle differences which may pop out, distinguishing one species from the other. As with so many other bird ID diagnoses, size matters, however, it’s that same old problem of comparisons. If there is a Red-tailed Hawk nearby, see if the black bird is larger in size, indicating a raven. For a quick and dirty assessment, birds in flight can be the easiest to determine species, because tail shape is a notable field mark. Common Ravens show what’s called a “wedge-shaped” tail, where central tail feathers are the longest, gradually decreasing in length to the outer tail. This gives the tail silhouette a more triangular appearance. Crows have a straight across or faintly rounded tail edge.
From the photos above, compare size and shape of Common Raven’s robust bill against the more pedestrian-sized beak of a crow. It can be used as powerful weapon and I’ve seen ravens repeatedly stab a ground-squirrel with that bill, then carry it off for a take-away meal. The neck feathers on a raven are shaggier compared to the crow’s smooth neck and can be raised by the bird to give an even more throaty scarf look.
Finally, the voice can be a give-away for species, especially from a distance when its difficult even to see the bird’s field marks. We all recognize “caw-caw” of an American Crow but listen for a deeper pitched “croak” or popping sounds, produced by a nearby raven. They make a variety of noises, sometime sounding like a bird shouting loudly. It’s so fun to watch ravens in the air. They will do barrel rolls and fly upside down or pass a stick from one bird to the other during mating season. Endearing evidence of a love of play and a sign of an amazingly intelligent group of birds.
** photos from top: raven, crow with baby crow, crow in flight, ravens in flight, ravens again