I stopped by Hammond Pond earlier this week and found it very quiet. The only activity consisted of a few ring-billed gulls out on the mostly frozen pond and then a handful of blue jays, starlings, juncos, song sparrows, and house sparrows. All the passerines were at the overlook eating bread crumbs.
With not much to report here, I thought it would be a great time to post some pictures from the sea wall of the JFK Library. When the local lakes freeze up, I enjoy checking out Boston Harbor for a change of scenery and the chance for some birds that love saltwater. Even though the crossbills were my main reason for heading to the JFK Library, the harbor was a big draw too. I found some fun birds including brant (its nice to remember that not all geese prefer golf courses), common eiders, white winged scoters, buffleheads, common goldeneyes, a common loon, horned grebes, and red-throated mergansers.
Common Loon
I was hoping that there might be some red-throated loons to help me practice my loon identification. And of course, whenever I head to the salt water in winter, I'm always hoping for razorbills, dovkies, or murres. But of course any alcid would do! One of these days I am determined to track some down.
This morning while walking in Newton Center, I saw a hawk up in a tree by the T station. This exact same tree has previously held a red-tailed hawk. But I was excited as this bird was the wrong size, shape, and color for a red-tailed. This smaller bird had to be an accipiter and I hate narrowing them down to Cooper's or sharp-shinned hawks (Cornell Lab of Ornithology as a great page on this tricky ID). This bird however, made me think she was a Cooper's Hawk. She was remarkably big, about the size of a crow, had a rounded tail, and appeared to have the right body shape (large head with forward set eyes and torso that doesn't taper). It also helps that accipiters in our suburban area are more likely Cooper's than Sharpies. If you have any other thoughts on this identification let me know! Just as I was walking around to see her from the front, she disappeared when my head was turned.
A few weeks ago, before the weather turned colder, I was driving by Crystal Lake, when I caught sight of a few ducks out of the corner of my eye. With my binoculars in the car, I decided to stop and see what could be found.
In the little park by the swimming beach there were song sparrows, chickadees, robins, and cardinals. As I was walking toward the lake I flushed a kingfisher who flew off to a new distant perch while giving his dry rattling call. On the water there were Canada geese, mallards, common mergansers, and hooded mergansers. and a single ring-billed gull flying overhead.
The mergansers and kingfisher certainly made it a worthwhile stop and it made me wonder why Crystal Lake isn't birded often. Then a week or so later, I returned to find that ice had formed and was making the eeriest sounds of squeezing as ice slid against ice. There was hardly a bird to be found except a lone nuthatch calling from the pines. So I assumed that the lake is either a hit or miss, but regardless I'm going to try and check out Crystal Lake more often!
This post is following up from last week on the crossbills at the JFK Library in Boston. I very much wanted to share the details on how the red crossbill was identified as a Type 3 or Western Hemlock type. But first, why do we even care about red crossbill types? (Most of my information comes from this article on eBird by Cornell ornithologist Matt Young, so definitely check it out if you want more details.)
Scientists and birders have known that there is a wide range of beak and head morphology within red crossbills in North America. Some scientists have thought that this variation in morphology might indicate distinct subspecies of red crossbill. Then, 20 years ago Jeff Groth learned that different populations of red crossbills could be identified by unique flight calls. So we now recognize "types" of red crossbills, not with calipers and a bird-in-hand, but by ear. (To be fair audio recordings need to be analyzed to be certain of identification.)
There are currently 10 identifiable red crossbill types that can determined by call. Most of these reside in high altitude pine forests out west. Though Type 1, the Appalachian Crossbill resides in the mid to southern Appalachians and Type 8 is in Newfoundland. The wide spread cone crop failure this season has lead to a large irruption of boreal finches as they search for plentiful food. Some birds like the common redpoll (recently spotted in Nahanton Park) mostly move south, but the red crossbills can irrupt clear across the country.
Red Crossbill Female
(Type 3 - Western Hemlock)
Scientists are very curious about how to categorize a red crossbills. Are they a species, a species with subtypes, a group of species, or something else? As different red crossbill types have different beak morphologies (small - big) and preferred food sources (hemlock, spruce, pine) they already have variation in physical traits and ecological niches which may indicate separate species (bill size and food choice are probably linked as bigger heads and beaks can crack tougher pine cones). Birds of different call types tend to mate with others of the same type, even though they may overlap in range and form mixed flocks at times. This type-recognition for mating further supports the idea of separate species. But as Matt Young points out, it is not known if this barrier holds up during different conditions, such as irruption year migrations (which only happen every 5 years or so). Could these types represent the modern equivalent of Darwin's finches and be an example of evolution in action? Thus the importance of identifying red crossbill types and obtaining audio recordings.
I started blogging because I really wanted to share some of the audio recordings I made at Nahanton, so the idea of recording birds (all from my iPhone ) in the name of science was too much to resist! Besides I thought the additional identification challenge would be fun. I was just lucky that I was able to find a red crossbill when I went looking last week. Most of the time she was silent, then she gave a few of her flight calls right before she flew off, but I was able to catch a recording. Watch the movie to listen to her flight call. Between 4-8 seconds the cracking noises were actually being made by crossbills (red or white-winged) as they pry open the scales of pine cones.
As soon as I got home I sent the audio clip off to Matt Young at Cornell for analysis, but then decided I should try and do the analysis myself. So I opened the audio file with Raven Lite (free software from the Cornell Lab of Ornithology) to see the audiospectragram. The program plots the sound frequency on the y-axis and time on the x-axis, additionally, louder sounds appear darker. Then I zoomed in on a single call note so that I could see all the details very well. After comparing the spectrogram to The examples in Matt's article and read the descriptions and it was clearly a good example of a Type 3 red crossbill! The sharp down, up, down, is unambiguous. It was amazing to me that one short note (a tenth of a second) could contain so much detail, and yet birds easily can distinguish audio details on this time scale. I needed a computer.
Red Crossbill Type 3
Flight Call Spectrogram
The type 3, or western hemlock, red crossbills primarily live in the Pacific northwest but they are the majority of the red crossbill types that have been identified in Massachusetts this season. As the name implies their primary food is hemlock, though spruces will also do (the ones I found were in Japanese black pines). The second most common is type 10, Sitka spruce, is also from the Pacific northwest and prefers spruces, or in he east, white pines. Interestingly, both type 3 and 10 are the smaller beaked crossbills. There are also a few eBird records in the state for types 1 and 2, though none near Newton. Our nearest red crossbills to Newton were found at Arnold Arboretum where both type 3 and type 10 red crossbills were identified. So keep your phone or camera (the audio from a movie also works) ready to record any red crossbills that come our way!
