Common Loon

Few would argue that the calls of the Common Loon are symbolic of unspoiled remote lakes, and quite a few developed ones. One of the iconic calls, the wail (a rising and falling “ooo-aaaa-ooooo”), is generally used between a mated pair. Two other common calls usually indicate a threat: the complex “yodel” (only given by males) and laugh-like “tremulo.” These are most often given in response to a predator or incursion by another male. The tremulo is the call most likely to be given in flight.

Like so many other species, loons have been negatively affected by human activity. By the early 1900s they had disappeared from much of New Hampshire, victims of unregulated shooting and egg collecting. Accelerating rates of shoreline development through the century reduced nesting habitat and exposed loons to frequent human disturbance. Pollution is another significant threat, with negative effects of acid rain (depleting prey populations), DDT (thinning eggshells, but not as badly as in some other species), and heavy metals such as mercury and lead (impaired physiology or death). Direct poisoning from the ingestion of lead fishing tackle is the single most important cause of death in loons in New Hampshire.

But loons are also testament to how quickly a species can respond to conservation measures. When the NH-based Loon Preservation Committee was founded in 1975, there were only 74 territorial pairs in the state. In 2022 there were 345. This increase is the result of dedicated efforts to protect nesting habitat through signage, provide new nest sites in the form of rafts, educate people about loons, and most recently a statewide ban on certain types of lead tackle.

Despite these gains, the future of loons in New Hampshire is still at risk. Human populations continue to grow and intrude into nesting habitat, and climate change has the potential to negate much of the species’ recent gains. Loons are a northern species, and increasing summer temperatures impose physiological stress, especially for females that need to sit on nests. Warmer temperatures can also alter prey populations, and even increase the prevalence of diseases such as avian malaria. In fact, some loon lakes in the state have lost breeding pairs or shown reduced productivity, a clear sign that there is still work to do if we wish to continue hearing their calls on moonlit summer nights.