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Results of the 2013 Dyke Marsh Breeding Bird Survey

Larry Cartwright Marks 20 Years at Breeding Bird Survey

The Friends of Dyke Marsh honored Larry Cartwright at the quarterly meeting on May 16, 2012, with a certificate of appreciation on this his twentieth year as the Coordinator of the Breeding Bird Survey. This activity, a continuing biological inventory of the Dyke Marsh Wildlife Preserve, has provided trend information on the Marsh since the 1960's. The Friends also gave Larry a portrait of his beloved Prothonotary Warbler. President Glenda Booth presided.

Larry Cartwright

FODM President Glenda Booth awards a certificate of appreciation to Larry Cartwright.  Photo by Dorothy McManus.

The 2013 Dyke Marsh Breeding Bird Survey was conducted as part of a continuing biological inventory of this hopefully soon-to-be-restored tidal wetland. The breeding status of each species was determined by means of behavioral criteria. Species were placed into one of four categories: confirmed breeder, probable breeder, possible breeder, and present.

    The official survey was conducted between Saturday, May 25 and Thursday, July 4, but any data collected outside of this period that confirmed a breeding species was entered into the database. This permitted us to weed out most migrants that do not use the marsh to breed. I also included information provided from the Sunday morning walks and reliable individuals to supplement data reported by the survey teams. The survey tract encompassed the Belle Haven picnic area, the marina, the open marsh, the Potomac River shoreline, and the surrounding woodland from the mouth of Hunting Creek to Morningside Lane.  The volunteers reported 76 species at Dyke Marsh between May 25 and July 4.  By the time data collection was completed, they had collectively categorized 36 species as breeders, 11 species as probable breeders, and 17 species as possible breeders.  An additional 12 species were present in the survey tract during the official reporting period, but were considered not to be in suitable breeding habitat.

Cedar Waxwing
  

Cedar Waxwing was again among the songbirds confirmed as breeders in 2013.  Photo by Ed Eder.

  
    Most of the regular songbirds that occupy Dyke Marsh during the breeding season were again reported in 2013.  Observers found Great Crested Flycatchers, Blue Jays, Carolina Chickadees, Tufted Titmice, Blue-gray Gnatcatchers, Cedar Waxwings, Orchard Orioles, and other common species busily attending to fledged youngsters as the breeding season progressed.  Two volunteers even located a Warbling Vireo nest with nestlings, never an easy task.  So I was quite surprised to see that we documented nest building for Eastern Kingbirds and Baltimore Orioles and confirmed both as breeders, but reported no young for either species.  That means that nesting activity was clearly underway for these birds, but that they either failed to produce offspring or we missed seeing them.  The situation seems odder because Eastern Kingbirds and Baltimore Orioles are two of the most prolific breeders at Dyke Marsh.

Yellow Warbler
  

Yellow Warbler could not be confirmed and fell to "probable breeder" status.   Photo by Ed Eder.

  
    The inability to confirm Yellow Warbler as a breeder in 2013 also was totally unexpected.  The species generally is confirmed with minimal effort.  A pair of Yellow Warblers even successfully fledged youngsters from a nest built just six feet from the boardwalk at the end of the Haul Road peninsula in 2012.  With few exceptions, Yellow Warblers have confined breeding activities to this peninsula and the largest of the adjacent islands.  In 2013 Yellow Warbler males established territories at the expected peninsula and island locations, but survey teams also discovered singing males at Pipeline Bay and a wooded area we refer to as Oriole Inlet just northeast of the Big Gut entrance.  A female Yellow Warbler was identified at Oriole Inlet on June 9, suggesting a possible breeding pair.  Yet we found no nest or young either on the Haul Road peninsula or at Oriole Inlet, and Yellow Warbler fell to “probable breeder” status.

    A welcome development is the apparent increase in the Marsh Wren breeding population, especially in the Big Gut.  Beginning with the 2002 survey, Marsh Wrens have been found primarily, if not exclusively, in the Narrow-leaf Cattails along the north side of the Haul Road peninsula and the main island.  Marsh Wrens were completely absent from the Big Gut in the southern marsh between 2007 and 2010.  In 2011 Marsh Wrens returned to a tributary of the Big Gut that we refer to as the Northeast Passage.  That year a high count of four Marsh Wrens and two nests was documented. The following year volunteers reported only two singing males and a solitary nest for a high count.

    Marsh Wrens were present again in the Big Gut in 2013, but in bigger numbers and with evidence of some success. On June 9, a survey team reported a Marsh Wren departing a nest with a fecal sac, clear proof of a nest with young. The highest count for a single survey was five Marsh Wrens and four nests, with singing males in the Northeast Passage and further south in a bend of the Big Gut that we call Heron Hook.  When plotting out the locations where the birds were reported, I estimate that there may have been up to seven territorial males present in the Big Gut in 2013.  In the area along the north side of the Haul Road peninsula, survey teams tallied a high count of seven singing males during a single survey.  The location plots of these birds indicate a maximum of 14 territorial males in the north during the 2013 survey compared to an estimation of less than a dozen in 2012.  Although the overall increase in the Marsh Wren breeding population is perhaps modest, it is certainly positive news.

Leaast Bittern
  

The Least Bittern is a "probable breeder" again in this year's survey.  Photo by Ed Eder.

  
    The Least Bittern, a high visibility bird at Dyke Marsh, unfortunately remained in the “probable breeder” category for the second straight year.  The data give no indication that the Least Bittern population has suffered population declines since the last time the species was confirmed as a breeder in 2011.  The highest number of Least Bitterns seen during a survey in 2013 was five and the year prior was six.  The highest number of birds documented in 2011 was only three.  Confirmation in 2011 occurred only because a canoeist was lucky enough to see a Least Bittern carrying nesting material to a partially constructed nest in the Big Gut.  Generally survey teams aren’t that fortunate and finding Least Bittern fledglings is hardly an easy task.

    Ospreys are a big hit at Dyke Marsh and the birds did not disappoint in 2013.  The breeding season began with 11 active nests in the survey area, but two nests constructed on root balls washed out by May.  At least three of the nine remaining nests were reported with young in 2013, including the popular Marina nest containing perhaps one of the most photographed Osprey breeding pairs in northern Virginia.  Two young fledged from this nest and by the beginning of July the juvenile Ospreys were perfecting flying and fishing skills.  The Marina nest also hosted Purple Martins that successfully used the slats at the base of the platform as nesting compartments to raise and fledge young for the second consecutive year.  The established Bald Eagle nest at Morningside Lane contained two nestlings in 2013 and survey team reports indicate that at least one of the young fledged.

Prothonotary Warbler
  

A Prothonotary Warbler is observed carrying food, perhaps to a nest of young.  Photo by Ed Eder.

  
    Prothonotary Warblers are the only cavity nesting warbler in the eastern United States and there are plenty of cavities available at Dyke Marsh.  These birds also happen to be a personal favorite of mine.  Approximately 16 males established territories from the south marsh below Morningside Lane to the upper end of the Big Gut where it passes under the George Washington Parkway.  Prothonotary Warblers seemed to have had a successful breeding season during 2013.  A nest with young was reported on June 9 in an area of the Big Gut that we coincidentally call Prothonotary Bay, and the previous day an observer witnessed a Prothonotary Warbler carrying food at Pipeline Bay near the Big Gut entrance.  South Marsh Inlet in the southern marsh hosted another nest initially discovered on June 16 and reported as still active on June 30.

    The Eastern Screech-Owl pair was again present on Haul Road, but we have no indication that they bred or even attempted to breed.  A January 29 report placed the red morph female in the same cavity near the Haul Road entrance that the owls occupied in 2012. In February she moved to a cavity further south on Haul Road.  An observer reported the pair at this new cavity on March 16, but in late April the gray morph male was found back at the original cavity.  The female was not seen again until June 30 in the company of the male near the Haul Road entrance.  Although Eastern Screech-Owls have been documented using different cavities to roost and breed, we have no additional information to determine what transpired between this pair during the 2013 breeding season.

    Honorable mention goes to Scarlet Tanager and Willow Flycatcher.  Scarlet Tanagers are not Dyke Marsh breeders, but a male singing near Morningside Lane in mid-May was still present on May 26, indicating that a territory had been established.  The territory seemingly was abandoned in June since the bird could not be relocated on subsequent surveys.  Willow Flycatchers, occasional Dyke Marsh breeders, were present at two locations during the survey period, but presumably did not stay to nest.  Finally, although a volunteer coordinator should not show emotion when conducting a survey, I have to say that the Carolina Wren was the most pitied species during the 2013 survey.  Brown-headed Cowbird fledglings were observed by two reporters during the breeding season. The host parents in both cases were Carolina Wrens.

    I have read several accounts that have speculated that many birds started nestling late in the 2013 season because of the cold and wet spring, and this may explain why we had no luck finding Eastern Kingbird or Baltimore Oriole young or even being able to confirm Yellow Warbler.  Perhaps that is true.  Certainly we found fewer nests this year than average.  I do know that for whatever we didn’t find, it wasn’t for lack of effort from the volunteers.  On the contrary, many of the volunteers have been doing this survey for over a decade, are attuned to what to look for, and work very hard finding every bit of evidence to confirm breeding.  With that, I would like to recognize those who took part in the 2013 survey, whether they actively participated on a survey team or provided supplemental data independently or during a Sunday morning walk.

    In alphabetical order, they are: Bob Beard, Andy Bernick, Dave Boltz, Glenda Booth, Ed Eder, Myriam Eder, Sandy Farkas, Kurt Gaskill, Susan Haskew, Gerry Hawkins, Elizabeth Ketz-Robinson, Dorothy McManus, Ginny McNair, Larry Meade, Roger Miller, Elton Morel, David “Nick” Nichols,  Laura Plaze, Marc Ribaudo, Rich Rieger, Don Robinson, Jessie Strother,  Paula Sullivan, John Symington, Maggie Symington, Bill Whitacre, Brett Wohler, Margaret Wohler, Katherine Wychulis and Bill Young.

    The 2013 Breeding Bird Survey Results:

    Confirmed - 36 Species: Canada Goose, Mallard, Osprey, Bald Eagle, Mourning Dove, Red-bellied Woodpecker, Downy Woodpecker, Northern Flicker, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Blue Jay, Fish Crow, Purple Martin, Tree Swallow, Northern Rough-winged Swallow, Barn Swallow, Carolina Chickadee, Tufted Titmouse, Carolina Wren, Marsh Wren, Blue-gray Gnatcatcher, American Robin, Gray Catbird, European Starling, Cedar Waxwing, Prothonotary Warbler, Common Yellowthroat, Northern Cardinal, Red-winged Blackbird, Common Grackle, Brown-headed Cowbird, Orchard Oriole, Baltimore Oriole, House Finch, House Sparrow.
    Probable - 11 Species: Least Bittern, Eastern Screech-Owl, Acadian Flycatcher, Willow Flycatcher, Red-eyed Vireo, Northern Mockingbird, Northern Parula, Yellow Warbler, Scarlet Tanager, Song Sparrow, Indigo Bunting, American  Goldfinch.
    Possible - 17 Species: Wood Duck, American Black Duck, Red-shouldered  Hawk, Red-tailed Hawk, Killdeer, Spotted Sandpiper, Chimney Swift, Ruby-throated Hummingbird, Hairy Woodpecker, Eastern Wood-Pewee, Willow Flycatcher, American Crow, White-breasted Nuthatch, Eastern Bluebird, Brown Thrasher,  American Redstart, Eastern Towhee.
    Present - 12 Species: Common Loon, Double-crested Cormorant, Great Blue Heron, Great Egret, Black Vulture, Turkey Vulture, Black-bellied Plover, Ring-billed Gull, Caspian Tern, Rock Pigeon, Blackpoll Warbler, Wilson's Warbler.

Definition of Categories:
Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.
Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached.
Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.
Present: Any species observed that is not in suitable habitat or out of its breeding range.
Definition of Safe Dates: We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant. Safe dates are simply defined as a period of time beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall. Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species.

Larry Cartwright
Dyke Marsh Breeding Bird Survey Coordinator

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Last Revised: June 29, 2014