Sibley Guides: Recent Episodes
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Possible? It might be, but most of the widely published “differences” are too subjective and/or too variable to be of any value. I dug into this a couple of years ago and discovered some details that seem more reliable, which are summarized in the one page file here (also as a pdf via this link: […]
I put together this matrix of variation in breeding plumage Rose-breasted Grosbeaks, showing the differences between each of the four age-sex classes. In this species it’s relatively easy to distinguish males from females, a little harder to distinguish one-year-old males from older males, and nearly impossible to determine the age of females. As in many […]
Estimating numbers of birds in flocks is a skill that we use a lot while birding, but something we rarely get to practice. And – it turns out – something we are really not very good at! I’ve put together a course that explains some of the science behind the challenge, offers lots of quizzes […]
I’ve just posted about 30 original gouache paintings for sale in the shop. Most of these were painted in 2016 for the app Song Sleuth, and show portraits of common birds singing. The rest are from the early 2000s and were painted for the NY Times syndicated newspaper column “Sibley on Birds” that was […]
The 2023 Clements/eBird taxonomy update has just been announced, and the biggest surprise is that Cattle Egret will now be considered two species! Few people are familiar with variation in Cattle Egret, and while the split won’t have much impact on North American birders I thought it would be helpful to describe the differences. At […]
In their 2022 checklist supplement the AOS voted to elevate the southwestern populations of Eastern Meadowlark to a full species, with the name Chihuahuan Meadowlark. it’s been recognized as a distinctive population for decades, usually under the name Lilian’s Meadowlark, but making it a full species raises the stakes and adds new emphasis to a […]
Common Grackle is a familiar backyard bird almost everywhere east of the Rocky Mountains, and shows some fairly striking regional variation in color. This variation involves mainly the colors of iridescence, and is most obvious in males. Females of the two extremes are readily identified, but the full range of intermediates is only apparent in … Subspecies of Common Grackle: Bronzed, Florida, and “Purple” Read More »
Stejneger’s Scoter is the Siberian counterpart of White-winged Scoter, only recently recognized as a separate species. The two species are very similar in all respects, and only adult males can be identified readily in the field. Stejneger’s is considered a very rare visitor to western Alaska, but my experience in Nome in 2021 suggests that … Finding and Identifying Stejneger’s Scoter in Alaska Read More »
I wanted to know if I could find an objective and reliable feature that would allow me to distinguish any elaenia from any empidonax, and it turns out it's the pattern on the folded wing. The presence or absence of pale edges on the primaries is the best single feature to focus on to be sure which genus you are looking at.
Jewelweed (wikipedia link) is a common plant in the northeastern US, where its late summer flowers are very popular with bees and hummingbirds. Its most notable feature, however, is its seed pods. When the tiny pods are ripe the slightest touch causes them to snap open, flinging the seeds in all directions (scroll down to … Why do Jewelweed seed pods explode? Read More »
For North American birders the most consequential change in the 2021 AOS Checklist supplement is the split of Mew Gull into two species – Short-billed Gull and Common Gull. For most birders this simply means changing the name of the species on your list from Mew Gull to Short-billed Gull. The North American population, common … Mew Gull is now two species! How to identify Common Gull and Short-billed Gull Read More »
I was fortunate to be able to spend ten days in mid May 2021 on Great Gull Island, an American Museum of Natural History research site at the eastern end of Long Island Sound, New York. The island is occupied in summer by a very large colony of Common and Roseate Terns (among the largest … Common and Roseate Terns high overhead Read More »
This is a helpful alert to anyone still using the original Sibley Birds app, which was has not been maintained or updated since it was replaced by the Sibley Birds V2 app in 2018. Some users are reporting that the app will not open after the latest iOS update (June 2021). If you are still … We begin to say a final goodbye to the original Sibley Birds app… Read More »
Prompted by a couple of recent records of Cave Swallows in the northeastern US, I’ve taken a fresh look at subspecies and done some new illustrations. In April 2021 Cave Swallows have been found in New Jersey and Massachusetts. Both have been identified as the Caribbean subspecies group. Since the 1990s Cave Swallow has been … New illustrations of Cave Swallow subspecies Read More »
Mid-March is when the first northbound Fox Sparrows show up in Massachusetts, and it’s always a pleasure to see this burly, richly-colored sparrow. I’ve been working on some new illustrations showing the variation among the birds in my yard this week. Regional variation in Fox Sparrow is extensive, and gets a lot of attention, with … Variation in eastern Fox Sparrows Read More »
Here is another recent project: I’ve been working on new and improved illustrations of Redwing for the bird guide and app, showing the differences between the two subspecies. The Redwing (Turdus iliacus) is a thrush common across Eurasia, from Iceland to Siberia. It is a very rare visitor to North America, mostly in Atlantic Canada … Distinguishing the subspecies of Redwing Read More »
Here’s a new illustration I’ve done as part of some work on distinguishing the two subspecies groups of Sandhill Crane. Six subspecies of Sandhill Crane are generally recognized, but for field observers it’s more practical to assign birds to two subspecies groups: Lesser and Greater. The Greater subspecies group includes five of the named subspecies, … Distinguishing subspecies of Sandhill Crane Read More »
Pine Siskins – streaky relatives of goldfinches – are so distinctive as a species that we tend to overlook their considerable individual variation. Siskins are unusual among the small finches in that males and females look nearly identical. Subtle individual differences in the amount or intensity of streaking, or in overall color, have no bearing … Variation in Pine Siskins and the so-called “green morph” Read More »
On sale 17 November 2020 from Clarkson Potter – a new Backyard Birds Jigsaw Puzzle for $19.99 A 1000 piece jigsaw puzzle featuring 49 species of familiar North American birds, with original artwork by David Sibley. A fold-out poster of the puzzle image is also included!