Friday, November 6, 2009
Thanks for your support!
Comments here are closed. All future posts will be at the new site, and all of the old posts and comments from this blog have been transferred there as well.
Tuesday, October 20, 2009
Juvenile (top) and adult (bottom) Canada Goose. 19 Oct 2009. Concord, MA. Photos copyright David Sibley.
- Juvenile overall has lower contrast markings, especially blurry and obscure pale edges on back feathers
- Juvenile has all feather tips narrow and rounded, vs adult feather tips broader and more square or flat-tipped. This creates a strongly barred pattern on the adult with pale lines straight across the back and well-marked pale and dark bars on the flanks.
- Juvenile has neck not quite as dark blackish as the adult, and the dark neck blends into the paler breast color; vs the adult has a truly black neck (in shadow in the lower photo here) with very distinct edge and no blending to pale breast (but in some dark western subspecies the black neck may blend into a dark brown breast even on adults)
Monday, October 19, 2009
Wednesday, October 14, 2009
Here are page-by-page corrections and changes for the Sibley Guide to Trees. This listing will be updated periodically as issues come to my attention. Please feel free to leave comments or send me an email if you notice anything that is not listed here.
p 3 - California Torreya, the common and scientific names should be justified left
p 28 - Red Pine needs a new name to distinguish it from Japanese Red Pine. I propose American Red Pine.
p 189 - Southern Red Oak leafy twig, the caption saying “acorn identical to Southern Red Oak” should instead say “acorn identical to Cherrybark Oak”
p 227 - Tung-Oil Tree - leaves should be larger
p 252 - Glossy False-buckthorn includes the three leaves at the top of the column and the map at the bottom. The yellow box of text and the three leaves immediately below that are Ceanothus. The map should be moved up above the box text to make clear that it represents the range of Glossy False-buckthorn.
p255 - Rose Family Intro, near bottom of column 1 should say "Plums and Cherries (Prunus) page 256" [not page 254]
p 302 - Slippery Elm, in the third sentence "fragrant" is misspelled.
page 332 - Intro to maples, the third paragraph begins "All maples have palmately compound leaves..." This should instead say "Nearly all maples have palmately lobed leaves..." And could go on to elaborate that a few species have the leaves so deeply lobed that they are compound, and Boxelder is unique among the maples in having pinnately compound leaves.
p 345 - Mountain Maple underleaf should be rotated with stem down, (same for Vine Maple)
p 392 - First line of text - capitalize Paulownia family
p 393 - Aralia Family, add a sentence saying "Castor-Aralia (p 322) is also a member of this family and should be placed here." [and in a future edition it will be]
Pignut p 145
Rose Family p 254
And it is suggested (see comments below) that species like Northern White-Cedar and Western Redcedar should have an entry in the index under "cedar". [and presumably there are other examples like this]
Saturday, October 3, 2009
In some cases, however, when you encounter a confusing tree, the presence of opposite leaves can be a useful pointer to help narrow the range of possibilities. So below I’ve put together a list of trees with opposite leaves. Interestingly, almost all of these species show up in the last 80 pages of the guide.
Definition from p xxiv of The Sibley Guide to Trees:
Leaves that grow singly from the twig, without another leaf directly across the twig, are called alternate, as they usually grow from alternate sides of the twig. Leaves that grow in pairs from opposite sides of the twig at the same level are called opposite. If three or more leaves all grow from the same level on the twig they are called whorled.These patterns can be detected even more easily in winter, as buds and leaf scars on the twigs match the arrangement of the leaves (either opposite or alternate), and branching tends to be opposite or alternate as well. Also note that twigs with alternate leaves tend to grow in a zigzag pattern, while trees with opposite leaves generally have straighter twigs.
Species counts only include those illustrated in the guide.
North American Trees with Opposite Leaves
- Katsura, Genus Cercidophyllum (p. 101) – one introduced species [the only species in its family]
- Eucalyptus, Genus Eucalyptus (p 109) – three introduced species have juvenile foliage opposite, but adult foliage alternate [Crape-myrtle, in the same family, has alternate leaves]
- Paper Mulberry, Genus Brousonettia (p. 248) – one introduced species [other genera in the Mulberry family do not have opposite leaves]
- Lyontree, Genus Lyonothamnus (p. 293) – one native species [other genera in the Rose family do not have opposite leaves]
- Beebee Tree, Genus Evodia (p. 321) – one introduced species [related to Corktree, but other species in the Rue family do not have opposite leaves]
- Corktree, Genus Phellodendron (p. 323) – one introduced species [related to Beebee Tree, but other species in the Rue family do not have opposite leaves]
- Buckeyes, Genus Aesculus (p. 326-331) – six native and one introduced species [related to maples, but other genera in the Soapberry family do not have opposite leaves]
- Maples, Genus Acer (p. 332-351) – 13 native and ten introduced species [related to buckeyes, but other genera in the Soapberry family do not have opposite leaves]
- Dogwoods, Genus Cornus (p. 355-358) – three (out of four) native and one introduced species have opposite leaves [Dove Tree, in the same family, does not]
- Buttonbush, Genus Cephalanthus (p. 374) – one native species [the only North American tree in the Madder family]
- Ash, Genus Fraxinus (p. 376-385) – 17 native and four introduced species [all other genera in the Olive family also have opposite leaves]
- Japanese Tree-lilac, Genus Syringa (p. 386) – one introduced species [all other genera in the Olive family also have opposite leaves]
- American Fringetree, Genus Chionanthus (p. 387) – one native species [all other genera in the Olive family also have opposite leaves]
- Common Olive, Genus Olea (p. 388) – one introduced species [all other genera in the Olive family also have opposite leaves]
- Devilwood, Genus Osmanthus (p. 388) – one native species [all other genera in the Olive family also have opposite leaves]
- Desert-willow, Genus Chilopsis (p. 389) – one native species with opposite or whorled leaves [related to Catalpas, other genera in the Trumpet Creeper family also have opposite leaves]
- Catalpas, Genus Catalpa (p. 390-391) – two native and one introduced species have opposite or whorled leaves [related to Desert-willow, other genera in the Trumpet Creeper family also have opposite leaves]
- Royal Paulownia, Genus Paulownia (p. 392) – one introduced species [the only species in the family]
- Elders, Genus Sambucus (p. 397) – many native species mostly shrubs [related to Viburnums, all other genera in the Muskroot family have opposite leaves]
- Viburnum, Genus Viburnum (p. 397) – many native species mostly shrubs [related to Elders, all other genera in the Muskroot family have opposite leaves]
Thursday, October 1, 2009
- The Margins are occupied by Savannah Sparrows and are rarely used by the other two species (almost never by Swamp)
- The Middle zone was used by all three species, although I would say it was preferred by Song Sparrow, and was used rarely by Swamp Sparrow.
- The Depths were the home of Swamp Sparrows, which rarely venture into the other zones. Song and Savannah sparrows would also go deep into the shrubs when alarmed (e.g. if a hawk flew by), but their typical behavior when flushed by me was to land on the outer edges of the thicket.
Check it out in your local area. I'd be interested to hear how it works in other places and with other species. And of course the same principle should be applicable to lots of other situations.
Wednesday, September 23, 2009
Tuesday, September 22, 2009
Two events related to The Sibley Guide to Trees: It is the featured product today on the Daily Grommet website. I’ll be checking in periodically, responding to comments and answering questions through noon tomorrow (Wednesday Sep 23rd) .
And “The Art of Identification” - a show of my artwork and field sketches at the Massachusetts Audubon Society’s Visual Arts Center in Canton, MA, will be opening this coming Sunday Sep 27th, and showing until January 2010. More details are here.
Thursday, September 10, 2009
Thursday, July 9, 2009
I should point out a very interesting new blog by Nathan Pieplow about bird vocalizations, with a comment on the Pine Siskin issue here, and lots of other good stuff. And another blog about bird voices by Paul Driver, with a recent post about Mimicry here.
McGraw, Kevin J. and Alex L. Middleton. 2009. American Goldfinch (Carduelis tristis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/080
Wednesday, June 24, 2009
Klem, Daniel, Jr. 2009. Preventing Bird-Window Collisions. The Wilson Journal of Ornithology 121:314 –321
Thursday, May 14, 2009
- longer and thicker bill with curved culmen
- darker and much thicker streaks on the underside
- darker streaks on the upperside and coarser and darker markings on the face
- Belding's never (as far as I could see) raises a crest, while the northern birds often look slightly crested and show a distinct peak on the rear crown
- Belding's in early March were singing and territorial, chasing each other across the marsh, while the northern birds were in small, loose flocks moving together widely across dry grassy and weedy areas around the marsh
- Belding's flight was low and weak, with round body and fluttering wingbeats, reminding me of Sharp-tailed Sparrow, unlike the stronger, higher, more "bounding" and undulating flight of northern Savannahs
- in early March the Belding's were all in clean fresh plumage, while the northern birds were molting and scruffy with missing feathers all over the head and body
I was struck by how much stockier and larger-billed the Belding's looked in comparison to the northern subspecies, in many ways intermediate between northern and "Large-billed" Savannah Sparrows. Apparently some populations intermediate between Belding's and northern birds are resident farther north along the California coast, but alongside the migratory northern subspecies the Belding's Savannah Sparrows in southern California seem quite distinctive.
Wednesday, May 13, 2009
[10 July 2009 - update added at end]
In July 1990 I spent several weeks birding in west-central British Columbia, where Pine Siskins were one of the most conspicuous birds, and I became convinced that Pine Siskins were copying the sounds of other species of birds and incorporating these sounds into their songs. I was able to identify American Robin (squeal call), Evening Grosbeak (“krrr” call), Warbling Vireo (scold call and a song phrase), White-winged Crossbill (flight call and trill), and even House Sparrow (calls).
Since then I’ve heard this in many other places, and come to expect it whenever I hear siskins singing. From late March to early April 2009 I had the opportunity to listen to several individuals repeatedly in my yard in Concord, Massachusetts, and I was able to identify the following 14 species in the siskins’ songs:
Evening Grosbeak “krrr” call
American Robin, flight squeal and single “pup” call
Eastern Bluebird, rattling flight call
Eastern Towhee, “chewink”
Black-capped Chickadee, a single “dee” note
Northern Flicker, “kew” call
Hairy or other woodpecker, “wika” call
Dark-eyed Junco, soft “tew-tew-tew” call
Eastern Phoebe, song phrase and chase call
Blue-headed Vireo, two syllables of scolding call
Red-eyed Vireo, scold call
Song Sparrow, “jimp” call
Ruby-crowned Kinglet, two-syllabled whistled song phrase
Common Redpoll, flight call
These sounds can be very challenging to pick out, since the song moves along so rapidly that the bird is already singing other sounds while your brain struggles to process and identify the previous sound. The Evening Grosbeak call is commonly used and distinctive enough to stand out each time, but other calls like the Eastern Bluebird rattle simply blend in with the staccato jumble of sounds.
In my yard the same sounds were used repeatedly day after day, so as I became familiar with them I was better able to pick them out, and started to notice other copied sounds. I could not distinguish individual siskins, so I don’t know how many sounds were shared among birds, but the fact that the Evening Grosbeak call and American Robin call were heard virtually every time I listened carefully (and were heard years earlier in BC as well) suggests that most or all siskins use these calls, and probably share a lot of other sounds as well.
If you’d like to hear some of this, check out the recording catalog number 133352 at Cornell's Macauley Library, July 2, 2007, recorded in Newfoundland by Geoffrey Keller. [You’ll have to Search audio for Pine Siskin, and then find this recording]
The bird starts singing at about the 40 second mark, and between 47 and 56 seconds imitates Common Redpoll, Evening Grosbeak, Hairy Woodpecker, Dark-eyed Junco, American Tree Sparrow and American Robin (and probably others). Notice the clear sing-song notes of American Tree Sparrow at about 55 seconds, with the abrupt “pup” of American Robin following immediately after.
Amazingly, this vocal copying seems to have been almost completely overlooked. In Bent’s life histories (online here) copying of Evening Grosbeak and (in a captive bird) Common Redpoll and Canary, are mentioned. A study of vocal copying by Lawrence’s and Lesser goldfinches (Remsen et al, 1982, pdf here) specifically says that the song of Pine Siskin does not include any copied sounds, and the Birds of North America account makes no mention of it.
Presumably the sounds that are learned are simply the ones that are common in the siskins’ environment, so siskins from the western mountains must learn some sounds that are not heard in the east, and vice versa. Another Macauley Library recording from California (catalog number 120288) includes copies of Lesser Goldfinch flight calls, among others. Given how much siskins wander, it would make a really interesting exercise to listen for copied sounds that are “out-of-range”. Hearing, for example, Eastern Towhee in British Columbia or Lesser Goldfinch in Massachusetts would give you some idea of how far that individual siskin has traveled.
Update - in early June 2009 I spent a week at The Nature Conservancy's Pine Butte Guest Ranch near Choteau Montana, and was able to hear several Pine Siskins singing. I was able to hear copies of the vocalizations of seven species there. In addition to the now-expected calls of American Robin, Dark-eyed Junco, Common Redpoll, and Evening Grosbeak, the Montana siskins copied Western Tanager call, Mountain Chickadee dee note, and a Cassin's Vireo song phrase. Clearly these birds had learned their calls in the west, and would stand out in the east. So the challenge remains – to find a siskin that has traveled cross the continent, and recognize it based on the sounds it has learned.