Christmas Bird Count 2023
Photo: Eastern Bluebird, P. Wainright, 16 Dec 2023
Introduction: The Christmas Bird Count (CBC) is run by the Audubon Society (see Audubon website), and takes place world-wide. It is a one-day snapshot of the number of birds seen in each species. Each region (ours is Greater Portland) has a local organizer, who coordinates the groups of birders in various sub-regions. Our sub-region is Peaks Island, and we are Sam, Valerie and Patty.
Highlights: We saw 49 species of birds between 7am and 3:30pm, including several species that we did not expect (for example, Razorbill, Winter Wren, Hermit Thrush). But we did not see some that we had seen on our scouting trip the previous day (for example, Mourning Dove, Red-throated Loon, American Robin and Wild Turkey). The Winter Wren that Valerie observed was the only one seen in the region (there were 55 birders in the Greater Portland region this year).
Photo: Winter Wren, V. Kelly, 16 Dec 2023
We counted the highest number (29) of Great Cormorants that we had ever seen on Whitehead Cliffs, Cushing Island since we began counting them several years ago. We saw three groups of Eastern Bluebirds (six birds in each group).
Photo: Eastern Bluebirds, P. Wainright, 16 Dec 2023 Interesting Questions? You be the judge:
Photo: Great Cormorant, P. Wainright1. Great Cormorants (GRCO): They breed on Nova Scotia and a small colony on Seal Island, ME (Egg Rock Update 2023), but migrate southward in the winter (Hatch et al. 2020). On Peaks, they roost each winter night on the Whitehead cliffs, facing northeast. 
Photo: Great Cormorants, P. Wainright
Imagine trying to get a good night’s sleep there during a Nor’easter. Why do they spend their winters here, while their relative, the Double-crested Cormorant (DCCO), spends its summer on Peaks and migrates south of here in the winter? They are both fish-eaters, but do they pursue different prey species?
a. The following is a summary of information provided in (Dorr et al. 2023). The DCCO is found throughout North America. They feed opportunistically in mid-water and on the bottom, on schooling or solitary fish and crustaceans. Examples: cunner, sculpin, flounder, rock gunnel, sand shrimp. When feeding on schooling prey, they may form loosely coordinated foraging flocks, sometimes in lines or shallow crescents. Nestlings can eat more than adults from day 21-160. Forty percent of energy consumed goes to regulating body temperature. Adults eat 20-30% of their body weight/day. Spreading their wings while perched on a rock is not for thermoregulation, rather drying feathers. Little is known about their winter diet.
b. Is the GRCO more tolerant of cold weather? Apparently so: The following is a summary of information given in Hatch et al. (2000). The GRCO is much more widespread than the DCCO; occurring in the Americas, Europe, Asia, Africa, Australia from 47 S to 74 N latitude. In the north Atlantic, in addition to locations already noted, it breeds in S. Newfoundland, and W. Greenland. They tolerate winter water temperatures of -1°C and air temperature of -30°C, and spend winters from Greenland to the Carolinas. However, maintaining a body temperature of 41 C in extremely cold water requires that they expend 2.7 times as much energy as Adelie Penguins. Do they pursue different prey species than the DCCO? The GRCO feeds deeper than DCCO, feeding mainly on bottom fish, up to 1.5 kg per day. They do not hunt in flocks, as DCCO do. Despite their high energy requirement, they spend <60 minutes per day feeding, indicating that they are efficient feeders. Differences between diets of Great and Double-crested cormorants at nearby sites during the breeding season suggest that the 2 species often feed in slightly different habitats [and possibly different prey]. Near Halifax, Nova Scotia, DCCOs ate more eel-like fishes (notably rock gunnel and wrymouth [Cryptacanthodes maculatus]). In Magdalen Is., Quebec, GRCOs ate relatively more flatfishes and cunners. They may have been extirpated from coastal Canada and New England in 1700s and 1800s. Hatch et al. (2020) does not provide further details. [Our speculation is that fishermen were responsible, seeing them as competitors, or perhaps food.] 
Photo: Razorbill, S. Wainright, 15 Dec 2023
2. Razorbill: We have seen them on Newfoundland in breeding colonies. They are a relative of the Great Auk (now extinct). Do they really have a very sharp bill, as the name implies, and what do they use it for? The following information is from Lavers et al. (2020). The species breeds mainly in Iceland, but small colonies are found as far south as Matinicus Rock, and Seal Island, Maine. There are 300 breeding pairs of these crow-sized birds in Maine. Each pair produces one single-egg clutch pre year. They deliver several fish to chicks, held in their beaks like puffins do. Their prey are mainly fish, but also euphasiid shrimp, and polychaete worms. They were heavily persecuted by humans for eggs, meat, and feathers; their populations were greatly reduced, even locally extirpated, across much of their northwest Atlantic breeding range by early in the twentieth century. 
Photo: Red-throated Loon, P. Wainright (top), S. Wainright (bottom), 15 Dec 2023
3. Red-throated Loon (RTLO): This species is a relative of the Common Loon (COLO), which is much more abundant in Casco Bay. When you see both species side by side they are readily distinguishable; the RTLO is smaller, more slender, with a bill pointed slightly upward. They do not have a red throat in their winter plumage. How do they differ in their diet or environmental requirements? The following information is taken from Rizollo et al. (2020). The Red-throated Loon (RTLO) has a northern circumpolar distribution, and breeds in small arctic and boreal lakes in remote coastal tundra habitat (In N. America, it breeds mainly on small ponds, where it “utters a call during breeding that is generously described as cacophonous”. During winter, it primarily resides along both Atlantic and Pacific coasts of N. America and Eurasia, the Great Lakes, and Black, Caspian and Mediterranean Seas. Because of its sensitivity to disturbance, its broad distribution in coastal tundra habitat, and its reliance on the marine environment during breeding, the Red-throated Loon has been identified as an indicator species for environmental change on its breeding habitat. It feeds mainly on fish, also leeches, worms, crustaceans.
Common Loon (COLO): Widely recognized as an indicator of aquatic health, populations may be adversely impacted by anthropogenic threats in both breeding and wintering ranges. Approximately 30 percent of the fall population migrates to the Pacific coast of North America, 70 percent to the Gulf of Mexico and Atlantic coasts. About 94 percent of the global population resides in Canada [presumably this means breeding season]. COLOs use two general foraging strategies: solitary and group foraging. They eat fish, and to a lesser extent, crustaceans.
Photo: Hermit Thrush, © August Davidson-Onsgard, MacCaulay Library
4. Thrushes have one of the most beautiful, flute-like songs. We associate them with summer; most of them migrate south of here in the fall. But the Hermit Thrush (HETH) is sometimes seen here in early winter, puffed up to stay warm, feeding on berries. The following information is taken mainly from Dellinger et al. (2020). It is the only species of Catharus that winters in North America, switching from a breeding diet of mainly arthropods to a wintering diet heavily supplemented with fruits. Early winter records suggest absence from regions with January temperatures < ?4°C. They are also limited by requirement for open water. [Indeed, the individual that we saw was perched in a winterberry bush, overhanging a small stream.] Limited observations of fruit foraging indicate that they plucks and swallows whole fruits; thus they are considered “gulpers” rather than a “mashers”.
5. Can we observe the effects of climate change with CBC data? Our CBC list of species included a number of species that breed south of Peaks Island, and others that breed well north of us. Is climate change influencing where they live? Sam’s father was a birder, who used to say, based on observations from approx. 1940s to 1990s, that Carolina Wrens and Northern Mockingbirds were southern birds and it was unusual to see them in CT and on Cape Cod in the summer. Now, they are not uncommon in Maine in the winter! This is supported by Vickery (2020). This may be just an anecdote, but the CBC data is designed to document such changes. Putting together the observations of thousands of birders, and comparing them one year against another can help reveal such trends. (for more information, search for “Christmas Bird Count”).
6. Why didn’t we see all of the birds that we saw the previous day on our scouting expedition? We spent the day before the CBC scouting the area, looking for places with lots of birds. We actually saw the Red-throated Loon on the day before, and were disappointed that we did not see it on the day of the count. And we saw Wild Turkeys in abundance the day before, but not on the day of the count. 
Photo: Wild Turkey, P. Wainright, 15 Dec 2023
When you think about it, we were wandering randomly around the island while the birds were doing the same thing, often trying to stay out of sight. Could it be that if you counted birds every day of the year you would never get the same count twice?
A fun encounter: While looking out into Hussey Sound with a telescope from Evergreen Landing (where we had seen the Razorbill and Red-throated Loon the day before), six young joggers (probably college-aged) stopped and asked us what we were doing. We told them about the CBC and let them look through the scope at several duck species; they were enthralled with how beautiful they are. It was a delightful interlude for both parties, to share our interest in birds with, perhaps, the next generation of birders.
Another fun encounter: We saw what appeared to be seven large water fowl, bobbing in the water near TEIA, but we did not recognize their calls. On closer examination, they were the Peaks Island mermaids.
Photo: Mermaids, P. Wainright, 15 Dec 2023
By: Sam Wainright
Reviewed by: Patty, Valerie, Marty, Michael, Michelle
References:
Dellinger, R., et al. (2020). Hermit Thrush, version 1.0. In: Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA
Dorr, B. S., et al. (2021). Double-crested Cormorant, version 1.1. In: Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.
Egg Rock Update. (2023). Newsletter of National Audubon Society's Seabird Institute.
Hatch, J. et al. (2020). Great Cormorant, version 1. In: Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.
Lavers, J., et al. (2020). Razorbill, version 1.0. In: Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.
Rizzolo, D. J., et al. (2020). Red-throated Loon, version 2.0. In: Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.
Vickery, P.D. 2020. Birds of Maine. Princeton University Press, Princeton, NJ
