Vexing Vocalizations by Steve Gerow

        I have always enjoyed birding by ear, and regularly encourage newer birders to learn as much as possible about the vocalizations of the local species.  It is often the best (and sometimes the only) way to get an idea of what species are present in certain habitats, and is a good way to detect the presence of unusual birds.  Reasonable skill in “by-ear” identification is invaluable, and often absolutely necessary, for certain types of bird censuses.  Also, some difficult identifications (certain flycatchers and the two dowitchers come to mind) are more certain if calls are heard.  Above all, it is just plain enjoyable to know what one is hearing in the field.

            Nevertheless, as in all good things, there are occasionally a few glitches. Some calls of certain species sound very close to calls of other species.  Sometimes closely related species are involved, like the “whit” calls of several Empidonax flycatchers, or the “chip” calls of Townsend’s, Hermit, and Black-throated Green Warblers.  Other times unrelated species are involved, e.g. the “peek” calls of Hammond’s Flycatcher and Long-billed Dowitcher (unlikely to be in the same place, but a call heard when walking through some trees along the immediate coast in September could cause one to wonder if it is a migrant Hammond’s or a migrant dowitcher flying over that same grove. . .such situations do happen sometimes). 

This winter brought a large irruption of Pine Siskins.  Back in fall, in the early part of the influx, I heard what sounded like Pygmy Nuthatches in a place where I didn’t expect to find them.  When I reached the tree the sound was coming from, I looked around for the nuthatches, and just saw a big flock of mixed goldfinches and siskins.  I soon realized it was siskins making the sound, a slightly harder and sharper version of their “pi-di-di-di” call, sounding a lot like the “pi-dip,pi-dip” chatter of Pygmy Nuthatches.  Not too long thereafter, I began to see a series of comments on this phenomenon on several of the Central California internet birding listservers.  Much of this was from experienced birders, some expert on bird vocalizations, who had similarly followed “Pygmy Nuthatch” calls, only to find Pine Siskins.  Possibly this season’s influx came from a siskin population that has a louder and sharper version of this call than local residents and other wintering birds, or maybe there was just a collective amnesia about what calls Pine Siskins are capable of making after the near complete lack of the species over the previous year.  Whatever the cause, it has caused me to take more care in identifying Pygmy Nuthatches by ear.

Lighthouse Field in Santa Cruz has a eucalyptus grove that has sometimes hosted out of season orioles.  The field’s open areas regularly have a handful of wintering Western Meadowlarks.  These meadowlarks will sometimes come into the eucalyptus grove and (rather uncharacteristically) forage under the trees.  One Western Meadowlark call is a rather strident “reek”, most often given when the birds take flight.  This is very close to one of the most common and characteristic calls of Hooded Oriole.  Usually the habitats of these two species don’t overlap, but someone trying to find wintering orioles in that eucalyptus grove could be confused (at least I have been).

Then there are the mimics.  A variety of species regularly or sometimes include in their songs imitations of other species.  Nothern Mockingbird and European Starling are well known for this, then there are California Thrashers, Lesser and Lawrence’s Goldfinch, sometimes Pine Siskins, and others.  Both Steller’s Jay and Western Scrub-jay have quiet “whisper songs” that regularly incorporate copies of other birds calls.  Those imitations that are incorporated into a song are usually fairly obvious by the context, though they may cause some confusion if heard briefly in passing, or in an interrupted song.  More confusing sometimes are the excellent hawk imitations (usually Red-shouldered and Red-tailed in this area) by Steller’s Jay.  Then there is the occasional call that turns out to be produced by a birder with a tape player. . .

The best solution to all this, it seems, is just to get out in the field and listen more.  Many confusing moments can be resolved by listening for associated calls that eliminate similar species, or by listening for subtle differences that distinguish species.  More listening in the field trains the ear, and also one learns when it is necessary to take a little more time and care to be sure of an identification (and try to get a look at what is doing the calling).  Once in a while “I’m not sure” has to be the answer, but then that is true of birding “by eye” as well.  And finally. . oh wait, I hear a bird calling. . .a “tock”, like a Lincoln’s Sparrow, or maybe a Dark-eyed Junco, and now I hear a “tick”, so it must be a junco, unless there is also an Orange-crowned Warbler in there . . .okay, it just gave a twittering call, so it’s a junco, I think. . .