As Murray, one of my blog subscribers pointed out, last week’s puzzler was one in which the answer was right in the title and it wasn’t even necessary to read the post or look at the photos! A black skimmer is the ONLY bird that has an upper mandible that’s shorter than the lower mandible.
Perhaps you were one of a handful of people who recognized this bird. Black skimmers are long-winged coastal birds whose range is pretty limited to a thin ribbon of area along the east coast and along the much of the southern west coast.
Black skimmers are fun to watch in action as they gracefully fly
along, dragging their lower bill through the water trying to hit a fish or other small animal to feed on. Black skimmers feed on fish up to 5 inches in length and on crustaceans. They hunt primarily at dawn and dusk (are therefore considered crepuscular) and will even hunt at night as when hunting they rely on their sense of touch rather than their sense of sight. When their lower mandible hits a fish, the bill snaps shut, trapping the unsuspecting animal inside the very effective “knife.”
Black skimmers are colonial seabirds that will nest in large groups, often with other species like gulls and terns. They dig a small depression in sand to lay their eggs. Interestingly, when the chicks are first born, the length of the lower and upper mandible is the same, but by the time they fledge 4 weeks later, the lower mandible will already be 1cm longer than the upper mandible.
Ready to switch tracks? Our next series of puzzlers features animal tracks in snow. Can you get the first one? It features a little box of tracks, with the two front feet landing behind the two back feet, side by side.