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To put it simply, I don't know how they do it. Imagine having to start your work day and being immediately inundated with phone calls, a non-stop video conference and pesky co-w0rkers who all had something really "important" they needed to confer with you about. No time to leisurely check a few e-mails while that first cup of coffee works its magic on the cobwebs that accumulate around one's senses overnight. You hit the dike and you must be "on," with all pistons firing. Counting the morning flight of passerines at the "dike" at Higbee Beach Wildlife Management Area in Cape May, New Jersey requires a rare combination of birding skill and focus.
Five mornings a week over the last two months (September 1-October 31 2010), this season's morning flight counter, Tom Johnson, has scrambled up the face of the 60-foot dike at dawn to record the amazing northbound flights that occur here in fall.
You are likely asking yourself, "northbound, I thought this was fall migration?" Yes folks, birds still migrate south in fall, but at Cape May geography and weather combine to produce a rare northbound morning flight. During fall, the best flights occur on the heels of overnight cold fronts with winds out of the northwest.
Songbirds are, for the most part, nocturnal migrants and northwesterly winds push them towards the Mid-Atlantic coast in a broad front. If they hit the southeastern tip of Cape May at dawn, all they see in front of them is water. Opting to continue south across open water during daylight would leave them too vulnerable to predation by raptors, so instead, the birds turn west and then north following the Delaware Bay coastline, many flying along just above the tree tops. Higbee Beach Wildlife Management Area is perfectly situated in this transition zone. The dike, the top of which is just above tree top level, is the ideal vantage point to witness this ornithological spectacle.
Some days are comparatively pedestrian, but on those rare occasions when the overnight weather patterns are just right, over 100,000 individual birds have been recorded from the dike in a single morning (http://www.birdcapemay.org). For the counters, it's hard enough to lay eyes on each individual bird that flies over and harder still to pick up enough pattern and detail in the subdued post-dawn light to actually identify birds to species by sight. In addition to sight IDs, Tom and others who do the counting, make many individual identifications by noting the subtle differences in size and shape, plus the calls the birds utter as they fly over. These birds are not singing full songs or giving the somewhat more familiar call notes that they offer while on the ground. The calls one hears from flying songbirds are very high-pitched, not very loud, and to the untrained ear (if you can hear them to begin with), nearly identical from species to species. "Was that a 'tseep' or a 'zzeep'?"
Making this job more challenging is that there are always lots of unofficial counters about. On a typical fall morning, dozens of other birders come and go from the dike. The locals in this vibrant birding community know not to ask Tom and his fellow counters questions as they work. But first-timers don't know the protocols. For this reason, there is a lower viewing platform with an interpretative naturalist who is there to explain the flight to visitors, allowing the official counter to operate with minimal distractions.
In the midst of a big flight there is no time to look away or to record data by writing it down, so the counters use an array of hand clickers to count individuals. More common species, like Yellow-rumped Warbler and American Robin have a dedicated hand-held clicker. When it is really happening, Tom and the "swing counter" who relieves him on the two days a week he gets to sleep in, adorn their hands with multiple shiny metal clickers. This data collection is spearheaded by New Jersey Audubon's Cape May Bird Observatory, which has been "officially" running these counts since 2003.
Addendum: As I write this piece on 29 October 2010, Cape May is experiencing one of those magical days that occurs only a few times in lifetime. We subscribe to a pager alert network ("KEEKEEKERR") set up by the Cape May locals to share rare sightings quickly. This morning, we awoke to a slew of new KEEKEEKERR messages. Here is a sampling of the excitement, with the locals telling the story.
OCT 28 Evening:
9:44 PM Doug Gochfeld: Excellent night listening/watching @ the Convention Center. 30 birds a minute.
10:04 PM Scott Whittle: make that 60/minute seen
10:48 PM Michael O'Brien: Pace of flight over convention center increasing significantly
11:02 PM Glen Davis: in o.c. (Ocean City?)- just slowed down a lot from 60+/min an hour ago
11:10 PM Scott Whittle: just clicked 300/min visual at convention center / Michael O'Brien says best flight since 1999
11:17 PM Richard Crossley: simply amazing. Get out of bed. Once in a lifetime at the convention centre
OCT 29 Morning:
5:49 AM Scott Whittle: dozens of birds on street and low flying Beach Ave and Cape May Mall - call in sick!
6:27 AM David LaPuma: Birds all over the villas. Sparrows and Hermit Thrush sitting on rd
6:29 AM Sheila/Marleen: It's like Xmas morning
6:30 AM Richard Crossley: lots of Yellow-rumped Warblers overhead. Lots Hermit Thrushes, sparrows, Northern Flickers, etc. Roads and doorways jammed.
6:33 AM Mike Crewe: just for balance: not a single bird seen or heard here yet
6:41 AM Mike Crewe: American Woodcock streaming over now
6:48 AM Don Freiday: American Woodcock streaming by Hidden Valley lot too, over 100 seen in 5 minutes
6:57 AM T. Kersten: Dunes DRIPPING with sparrows, Yellow-rumped Warblers, juncos, robins
7:07 AM Richard Crossley: trying to drive to the point through clouds of sparrows that are increasing by the minute. Wild.
7:19 AM Tom Johnson: Cave Swallow Hawk Watch
7:53 AM Michael O'Brien: Dead Le Conte's Sparrow in my pocket; picked up on Cape May Point.
8:54 AM David LaPuma: Bayshore lousy w/ birds. Yumps, sparrows, flickers, etc.
9:09 AM B. Brown: Black-throated Blue Warbler Blackburnian Warbler, Hermit Thrush at Cape May State Park
9:35 AM Bob Fogg: Grasshopper Sparrow: 320 Alexander Ave.
9:48 AM Don Freiday: Just got a very interesting description of Golden-crowned Sparrow Higbees near lot
10:21 AM Tony Leukering: Lincoln's Sparrow putting on good show at Hawk Watch
11:51 AM Bob Fogg: Clay-colored Sparrow at 613 Seagrove Ave.
Editor's note: The nature of individual texts was casual and unedited. Abbreviations were spelled out and some other editing was done for clarity. We thank all of those who posted to KEEKEEKERR for allowing us to vicariously share their joy. Having just returned from my first trip to Cape May, the landscape is fresh in my mind and I am hopelessly trying to imagine the scene being described in the messages above. What I wouldn't have given to be there last night and this morning.
In the Pacific Northwest, Acorn Woodpeckers (Melanerpes formicivorus) have been reported with increasing frequency over the last few years. The northernmost confirmed nesting population of this species occurs in Lyle, Klickitat County, Washington, many miles from the nearest regular territories of the species. Population density increases slowly southward and then markedly in the oak habitats of southwestern Oregon and into California.
Similar wanderings of many bird species are often attributed to a decreased food supply within their usual ranges. If we apply this explanation to the recent Acorn Woodpecker reports, it would indicate that the acorn crops have failed within the home ranges of these individuals. Failed acorn crops may be a factor in these recent forays, but the dynamic natural history of this woodpecker makes the situation a bit more complex. Below, I offer some alternatives.
In general, Acorn Woodpeckers eat acorns from about August through May, but more so in the fall, as the crop ripens. From winter through summer, they supplement their forage with sap (usually from wells they make themselves). They will also eat insects/arthropods any time of year, with insects becoming their primary food during the breeding season. In all seasons, they prefer insects, whenever they are available. Their bill and tongue morphology indicate that they are generalists, although the bill shape may also make it easier to carry acorns. Their wing and body morphology are specially adapted for catching flying insects.
Acorn Woodpeckers are generally non-migratory, and they are only resident in regions with a reliable acorn source. In addition to acorns they also need granary, or storage, trees (although one small population in the Southwest has plenty of acorns but no storage trees, and they have adapted to this by migrating). Most Acorn Woodpeckers will remain on their home territories through the winter, as long as they have a reliable food supply.
Breeding Bird Survey data for Oregon (with the highest degree of credibility for the survey) show an increasing trend in the state since the mid-70s, with an increase of approx. 7.8% per year since 1980 for the 14 routes in the state where the species is reported.
Acorn Woodpeckers live in family groups, which at a minimum are comprised of a breeding male and female. Sometimes male, and to a lesser extent female, offspring from prior years may remain on the natal territory for up to 10 years, where they help to raise subsequent broods. These helpers may even breed, or attempt to breed, in the same nest as their parents—but this is another story! Also, males generally outnumber female fledglings each year, possibly explaining the dynamics of this highly social behavior.
The Acorn Woodpecker is considered a pioneering species. A few months after fledging, juveniles begin prospecting outside their home territories in search of their own territories and potential mates. They may stay on their natal territories for years, but they are always searching for new ones. Suitable habitat for a new territory must have three things: potential nest-cavity substrate, generally snags or dead branches of live trees; oak trees, for the fall feeding ritual; and granary trees, typically trees with soft thick bark, e.g. Douglas-fir, but also snags or artificial
trees such as power poles. Once they find suitable habitat, they may attempt to attract a mate and establish a new family group.
If they do not find suitable habitat, they probably just keep searching. After all, they are compelled to produce offspring. California is the locus, or heart of the range of “Baird’s” Acorn Woodpecker (M. f. bairdi), the subspecies found in the Pacific Northwest. California populations generally live among multiple species of oak tree. Sometimes, if one oak species experiences an acorn crop failure, others may still produce. In Oregon and Washington, we generally have one oak species, the Garry Oak or Oregon White Oak. An acorn crop failure of this single species would presumably force birds to relocate in search of suitable fall forage.
Single-oak-species habitats have another problem. The removal of these oak trees from the equation (for whatever reason) will force oak-dependent species to look elsewhere for food. And it just might force Acorn Woodpeckers to go well beyond their normal range in search of acorns.
Starting to get the picture? With recent steady growth in the Oregon population of Acorn Woodpeckers, more individuals are out scouting for new territories, and they may travel quite a distance in search of suitable habitat. A bumper acorn crop in Oregon could result in even more offspring produced, and hence an increase in the number of pioneering individuals during the fall. A failed or absent acorn supply may send them even farther to feed in that season. If they find new habitat that is suitable for breeding, they just might stay (e.g. Lyle, WA). If do not encounter optimal conditions, they may return to their natal territory for the next breeding season. Some individuals may even continue to pioneer long distances, many hundreds of miles in rare cases, never returning to where they were raised.
It is exciting to see many birders’ lives brightened by the unexpected presence of this very charismatic and fascinating species. And you can probably count on it happening as long as there are Acorn Woodpeckers.
Special thanks to Acorn Woodpecker guru Dr. Eric Walters of Cornell University for reviewing this article. Eric leads the current research on the longest known study of any woodpecker population on the continent, and perhaps the world: the Acorn Woodpeckers of the University of California’s Hastings Reservation in Carmel Valley, California.
Steve Shunk is a professional naturalist and woodpecker specialist living on the east slope of the Oregon Cascades. He is also the author of the seriously-almost-finished Peterson Reference Guide to Woodpeckers of North America.