The low water level of most small ponds and streams this fall has at least one silver lining, and that is that consumers of fish and other aquatic creatures expend far less energy finding prey, for it is all concentrated in much smaller bodies of water. The few puddles of water in small streams contain a vast amount of life, as do small ponds.
The Great Blue Heron has the advantage of having a varied diet that is found in a variety of habitats, so it forages in grasslands, marshes, intertidal beaches, riverbanks and ponds. While amphibians, invertebrates, reptiles, mammals, and birds are all known to have been eaten by Great Blue Herons, fish are their mainstay. They often forage in ponds, where they typically wade or stand in wait of prey in shallow water, which has not been in short supply this summer and fall. While the low water level is wreaking havoc with beavers and muskrats, it provides bountiful fuel for herons, egrets, kingfishers and other birds that forage in small ponds and streams as they wend their way southward.
Sea Lampreys aren’t a common sight, but an opportunity presented itself after this Bald Eagle “rowed” from the middle of the Connecticut River to the shore with its too-heavy-to-lift prey, ate a portion of it and flew to its nest with a slightly lighter load. At first glance I thought it had captured a large snake, but closer inspection revealed that a three-to-five pound Sea Lamprey approaching 30 inches in length was clasped in the eagle’s talons!
Lampreys were accidentally introduced into the Great Lakes and Vermont’s Lake Champlain, where they became parasites of other fish due to being landlocked. However, during the time the native Sea Lampreys are found in the Connecticut River, they are not parasitic. These fish are anadromous – they live as adults in the ocean (where they are parasitic) and return in May and June to spawn in fresh water.
Sea lamprey young spend three or four years as worm-like creatures burrowed in the soft mud of the Connecticut River. When they reach five or six inches (which can take up to ten years), young lamprey head for the sea. The ocean-dwelling adults uses their round, rasping mouth – filled with concentric circles of teeth – to scrape a hole in the side of a host fish and feed on blood and body fluids before letting go. They weaken, but don’t kill, their hosts. After spending one to two years in salt water, Sea Lamprey head back to the closest freshwater stream or river, migrate upstream, cease feeding and spawn. They never return to the ocean, as they die after mating and laying eggs.
Eagles obtain food mainly in three ways — by direct capture, scavenging for carrion and stealing food from other birds and mammals. When securing their own live prey, they hunt from perches or soar over suitable habitat, taking most prey on the wing. Bald eagles’ preferred food is live fish, but they are opportunistic foragers that select prey based on availability. Twenty studies from across their range found that the composition of bald eagle diets averaged the following: fish-56%; birds-28%; mammals-14%; and other 2%.
In addition to capturing live prey, eagles rely heavily on fish, bird and mammal carrion, especially during the winter. Ice fishermen’s leftover bait and/or rejected catches, roadkills and deer that have slipped and died on ice-covered ponds and lakes are three heavily-used sources of food at this time of year. If the carrion is small enough, it is often carried to a perch (see opossum in photo) where it is inconspicuously consumed. Larger carrion, such as white-tailed deer, salmon and waterfowl, that are too big to carry off, are eaten on site and repeatedly visited until consumed.
Hooded Mergansers are short-distance migrants that can be found in eastern North America year round where ponds and rivers remain open and slow-moving fish, insects and crayfish are plentiful. Some individuals migrate south and southwest in winter — 80% of birds banded in Maine, Vermont, New Hampshire and New York were recovered in coastal Atlantic states from New Jersey to Florida. A smaller number actually migrate north to spend winters in the Great Lakes and southern Canada. While numbers swell in March/April and November in northern New England due to migration, if there is open water you may well see Hooded Mergansers this far north throughout the winter.
Common Gartersnakes mate soon after emerging from hibernation in the spring, in March or April, and four months later the females give birth to live young. The newborn snakes are 5 to 9 inches long at birth and from day one have to fend for themselves. Their diet at this early stage consists of earthworms, insects, slugs, tadpoles, small frogs and fish. If there is an abundant supply of food, the young snakes can grow as much as 1 ½ inches a month during their first year. Earthworms are their preferred diet and gartersnakes are known for their ability to find them, even underground. It turns out that earthworms produce a chemical substance in their skin that is easily detected by (and attractive to) Common Gartersnakes. (Thanks to Eli Holland, who located the worm-eating newborn Common Gartersnake in the photograph.)
The fluffy, black loon chick that was the subject of Naturally Curious posts a couple of weeks ago is a month old this week (original photos were taken several days before posting), and it has undergone several transformations. Two weeks ago the black down of the newborn chick was replaced with a second coat of down that is brown in color. Between three to four weeks of age, its body elongated and its bill began to lengthen. In another week or so, the first gray contour and flight feathers will begin to replace the down, a process that takes about three weeks.
Both parents are very attentive and are providing as many fish and crayfish as the chick can consume, sometimes making the chick dive for its meal, sometimes not. Because one egg failed to hatch, the lone chick receives all of both parents’ attention, guaranteeing a full stomach. It isn’t unusual to see both parents dive, come up with fish in their bills, and deliver their catch simultaneously to their chick.