Some reverse snow birds are visiting the Cape from Florida this week. Two White Ibises have taken up a temporary residence at Mass Audubon’s Wellfleet Bay Wildlife Sanctuary, representing only the fifth ever record for the Cape and Islands.
If you’ve been to south Florida, then you’ve seen White Ibises, whether you remember it or not. While ultra-rare this far north, this species reaches a city-pigeon level of commonness down there, easily seen in wet ditches along the highways, in city parks, and even on lawns. They also occur in big flocks throughout the wilder portions of the Everglades, which is why they always remind me of my first bird research gig after college, when I helped with research on wading bird distribution and feeding ecology in the Southern Everglades. It was pretty good work for a young bird guy in training.
White Ibises are the most abundant wading bird in those vast marshes, where they range over huge areas to find drying pools where they can feast on fish and crayfish. Though a few colonies of 20-30,000 birds still remain, the reality is that only a fraction of their historic population has survived the large-scale draining of the Everglades for development during the first half of the 20th century.
Beautiful at a distance, White Ibises are sort of funny looking up close. They have staring pale-blue eyes set in a bright red face, from which that enormous red schnoz of a bill protrudes seven inches out and down. Big, gleaming white adults are easy for even a rank beginner to identify. But the Wellfleet birds were immature, which had some folks confused at first. How do I know they were immature? Were they smoking cigarettes and asking the older birds to buy them beer? No, it was by their plumage. Young birds have brown backs and wings, and a paler, mottled grayish head and neck.
But they still have those bills. And the two birds at Wellfleet Bay have been using them to terrorize the local fiddler crab population, which numbers roughly a bazillion at the sanctuary, scientifically speaking. In this way they are similar to another long, downward-curved bill-having, crab-gobbling bird that you can find there, known as the Whimbrel. Long, de-curved bills are perfect for extracting fiddler crabs from their burrows when necessary, though we have so many of these hapless crabs that the birds can just sort of walk around and feast on them at will, the crabs scattering before them like fairy tale villagers fleeing a giant. Male fiddler crabs have that one enormous claw, and piles of those claws in a marsh usually tell you Whimbrels have been feeding there, though our locally breeding Willets are probably the most likely culprit in most marshes.
The ibises have been present at Wellfleet Bay every day since they were found on Friday, so it’s worth a shot if you want to get a look at these super-rare visitors. Mass Audubon members get in free, and the folks at the desk can direct you to the best place to look for them. Or, you could just follow the sound of screaming fiddler crabs.
