Frozen water

This adult peregrine falcon had just finished a large meal, allowing for a close approach. Several are frequenting the Island this winter, most often seen along shorelines and in open areas. — Photo by E. Vernon Laux

Thawing and freezing repeatedly is what the winter months are all about at this latitude. For waterfowl, frozen water, or ice, creates all sorts of problems. Freshwater freezes at 32 degrees Fahrenheit. Freshwater also expands when it changes from a liquid to a solid. Any homeowner with burst pipes can attest to this.

Saltwater on the other hand is an entirely different substance in terms of its freezing properties. Due to the solids (minerals, primarily salt) suspended in it, in other words the salinity content, which varies considerably from place to place and time to time, it freezes at a different and not always constant temperature. Having grown up with the Fahrenheit scale, this writer prefers it as a more precise means of measuring water temperatures, especially the freezing point of saltwater.

Saltwater freezes at a different temperature and behaves differently when frozen than freshwater. It generally freezes at between 28 to 29 degrees Fahrenheit. The minerals suspended in the water (mostly salt) act as a catalyst to resist freezing. When it finally freezes the resulting ice is pliable when thin, only hardening once it attains a certain thickness. Due to the vagaries created by the salt content, tidal flow, marine currents, and a slew of other things, frozen saltwater is extremely dangerous to venture upon.

Mid-winter excitement

Mainland Europe is experiencing a severe cold snap – perhaps the worst ever recorded. Many over-wintering birds are fleeing the cold and heading west to the British Isles and beyond. Observers in Ireland have reported steady streams of various species of birds heading west. Already during the first part of January many of these very rare European strays have already been spotted across the Atlantic Ocean in Newfoundland, some 940 miles northeast of the Vineyard. It is hoped some of these birds will continue down to visit our region.

On January 5 a northern lapwing (Vanellus vanellus) was discovered near Cape Race, Newfoundland. A day later several others were discovered in southeast Newfoundland. The distinctive, frequently given shrill flight call is unique. The only northern lapwing ever seen in Massachusetts was discovered by Alan Keith of Chilmark at his farm on December 26 through 30 in 1996.

The northern lapwing is a Eurasian species, usually appearing as singles in North America. However, hundreds of birds, thought to have been driven by strong north Atlantic storms, occurred in December 1927 and in January 1966. Outside the breeding season, northern lapwing often appear on harvested stubble and plowed fields as well as in pastures and occasionally on mudflats. Perhaps this winter’s weather patterns will produce another banner year for this species in North America. Time will tell.

Another bird, a reclusive redwing (Turdus iliacus), a thrush in the same genus as American robin, associated with a flock of American robins and cedar waxwings, was also found in southeast Newfoundland on January 13. This redwing is a frequent vagrant to Greenland, sometimes in large numbers, and a small population has bred in western Greenland since late 1970. This migratory species also has a resident population on the Iceland and Norwegian coasts, Scotland, and in the southern Baltic region.

The bulk of the population, however, breeds from northern and eastern Europe, east across Siberia. This population winters south of its breeding range in western and southern Europe, northern Africa, the Black and Caspian Sea basins, and southwest Asia. In winter, it feeds primarily on seeds and fruits. The redwing is a common bird in its range with a population estimate of between 5 million to 6.5 million pairs. There has never been one of these birds seen anywhere in New England. Maybe this is the winter it will happen.

Check flocks of robins carefully

Despite or because of the very harsh conditions, birds have been easy to see. Activity at bird feeders has been as good as it gets. Reports of strange birds, species that observers had to look up in their field guides, showing up at feeders where they had never been seen before has become a daily occurrence. It is gratifying to learn how many people are not only feeding birds but are actively monitoring what species they are.

Mixed flocks of birds that eat fruits and berries, frugivores, have been seemingly all over the Island. American robins, eastern bluebirds, cedar waxwings, yellow-rumped warblers, and small numbers of other species all feed, flock, and travel together in the winter months. The various species all eat the same foods and apparently derive some advantage in finding it by staying in large flocks. More importantly, there really is safety in numbers and all species benefit by having more eyes alert to and looking for predators. The security benefit to individual members of the mixed flock far outweighs any detriments to traveling in large groups.

Until next time – keep your eyes to the sky.