Date: 4/3/25 7:15 am From: 'PAUL ROBERTS' via Arlington Birds <arlingtonbirds...> Subject: [Arlington Birds] Some Things are Tough to Swallow
When you're been birding almost daily for more than fifty years you've tended to see a lot. Some of it you forget over the years, some of it you look forward to every year, and sometimes you see something you've never seen before, which can be surprising when birding locally. Several weeks ago I spotted a Horned Grebe in basic plumage splashing down into the Lower Mystic Lake around dawn on a dark, stormy day. It landed right in front of me, submerged several times, and swam away. I saw it briefly over several days, when I saw it dive southeast from the dam viewing platform and come up with a small eel, thread-thin and about 4-6 inches long, but very thin, like thin spaghetti, or perhaps even angel hair pasta. I've seen eagles catch large eels (one of their favorite foods) at the Mystic Lakes, and gulls and ducks catch what I would call small eels there, but I had never seen anything catch an eel this small, though I had seen these thin thread-like fish climb the fish ladder during the herring migration, when fish counts are made. The tiny eels look blackish, not transparent like the earlier "glass eel" stage," and they are incredibly robust. When captured they wiggle and writhe; they often try to wrap themselves around the beak of the predator so it can't swallow them, and at times wad up into a tight ball, apparently to make it harder for the bird to grab or swallow the eel. Each time I saw this bird land in the same spot; dive several or more times for 5-10 minutes; catch two eels; and paddle away to the other side of the lake. I had the clear feeling it was shy and wanted to avoid human activity, including hearing human voices. It was always alone; not feeding in the midst of ducks cormorants, or roosting gulls. Each time the stay was brief, so a photographer friend who really wanted to photograph the grebe missed it day after day. The bird was seen up by Sandy Beach and down by the river. It apparently worked both lakes daily, and in a routine because I tended to see it around the same time every day in the same spot. Two days ago it arrived a little later, but very close to the platform, and it did not leave. Over just less than an hour, it caught and swallowed at least 15 eels! Some observers might have thought it caught more, but that would have been misleading because I saw eels swallowed and then repeatedly escape from the grebe's throat and beak.The grebe would recapture it quickly and then slam the thin, writhing fish against the water repeatedly while holding on. It appeared at times to dive with the eel in its beak as though hoping to swallow water to facilitate the capture, but it appeared that at times eels used the water to escape. Some eels clearly escaped multiple times. I was looking for eagle activity during this, but this was so unusual I focused most of my attention on it and took numerous photographs. Can you imagine trying to eat live, writhing wet angel hair pasta without using your hands, much less any utensil? While it was actively swimming? I had never seen anything like this, and was amazed that the grebe had been able to find so many eels in one spot maybe 30 yards off the dam. Then I found out why. I have been mystified by American eels for several decades. The opposite of anadromous herring, which live in the oceans but go into the freshwater streams where they were hatched to spawn every year once they are adults, our American eels live their adult life in freshwater but migrate to the Sargasso Sea to lay their eggs. The young hatch and as minute fish they float in the currents and then with powered swimming apparently go to where their ancestors came from (I think this is open to debate), but the net result is that while adult herring are swimming up the Mystic to spawn, adult eels have migrated south thousands of miles to lay their eggs in warm open water. While the adult herring are "running," young glass eels or elvers are "returning" to presumably ancestral waters to live to adulthood, before they migrate down those rivers to spawn in the Sargasso. Courtesy of Kartsen Hartel, local noted fish authority and author, I had his book on "Inland Fishes of Massachusetts," (he was lead author) and his copy of the "Bible," the epic "Bigelow and Schroeder's Fishes of the Gulf of Maine." (3rd edition, edited by Bruce Collette and Grace Klein-MacPhee.) More is known about the eels in their freshwater habitats than in their saltwater breeding grounds where almost nothing is known. For many diurnal birds of prey the female is notably larger than the male, as much as 15-30%. Female eels are much much larger than the male. Males normally reach 12-14 inches in total length, but females are 14 inches to over 52 inches. They need that size because when they migrate they may be carrying 2.5 to as many as 10 million eggs! In Karsten's book, he describes how the young elvers (young eels are called elvers) move from the small, transparent, "glass eel" stage to dark elvers along the Massachusetts coast in March, when they begin migrating up stream. It seems quite possible the Horned Grebe "stumbled" on a mass of migrating young elvers. (It is also possible that he found a bed where large numbers of local elvers like to "bed" for the day, as they tend to be nocturnal.) Whatever, I have never seen anything eat 15+ eels in an hour. Moreover, there was large migratory movement that night and I have not seen the grebe since, so it is possible he/she was feasting on eels to fuel the beginnings of a long migratory flight to the western U.S. or Canada, where they breed. I should note that I saw MK and KZ catch many large eels on the lakes, and know where they have repeatedly found some of the largest eels I've ever seen. I'll never forget when MK returned from the lakes to her fledgling in the cemetery and generously gave an eel several feet long to her offspring. The poor kid had been begging for food all morning, so MK delivered this huge eel to it. But the kid could not understand how to eat an eel; it was not like other fish. You apparently had to peel it like a banana. The kid cried and cried, prompting MK to come back and start eating the eel in front of the kid (like Mom or Dad unwrapping a plastic-encased toy made in China.) The kid got the hang of it, started eating, and later carried the remains of the eel high to a 60+ foot pine, where it dined on it over the course of the entire day! I've seen hundreds,probbaly thousands of Horned Grebes feeding off our coast every winter. I had never seen what they were eating before, much less how and how many. Eels are only one of their myriad prey items. Best, Paul Paul M. Roberts Medford, MA <phawk254...>
