C&O Canal 2003 Report

Overview

Results of the Fifth Annual Chesapeake and Ohio Canal National Historical Park Mid-Winter Bird Survey have been finally tabulated and are being circulated by email to participants, and posted on DC Audubon’s website at . Participants received the initial version for comment by email April 21, but again, I apologize for not getting the results out much earlier to a wider audience. Circulation in March, in time for winter regional reports to North American Birds, is desirable and certainly achievable with more diligence on the part of the coordinator.

We had an enjoyable count as always, although numbers were fair-to-middling and variety was unexciting. Our total of 84 species was only the fourth highest in the five years of this count, despite good coverage and clear skies. Orange-Crowned Warbler in lower Montgomery County - one well described and another by elimination - was the only species new to the count. No species counts, in my view, were so high, low, or unusually distributed as to necessarily imply real ups or downs in 2003.

Coverage and Participation

Saturday, January 25, 2003 was fair and cold. Unlike 1999-2001, we had neither predicted nor actual precipitation, and unlike 2002, there were no shirtsleeves and very few hikers and bikers ( a few skiers). Temperatures in DC-Montgomery segments rose from early morning high teens to mid-afternoon 40’s; in Western Maryland, from about 10° to mid 30’s. The ground and Canal were snow-covered and most of the Potomac iced over, but winds were light.

176 mile-segments (milepost to milepost) were covered, out of a possible 185. This is just a little short of the record 178 miles in 2002. Again, 100% coverage was within reach, but missed due to coordination errors. Counting and reporting should be on a strict milepost-to-milepost basis, to facilitate comparisons within a year and between years, but this was done in only 170 of the 176 mile-segments. Reasonable assumptions and approximations, including the coordinator’s assignment of crow and chickadee “sp.” reports, were used to arrive at the figures for number of mile-segments in which a species was observed.

At least 100 individuals participated, per reports of the 61 nominal principal observers. As in 2002, some excellent birders joined this count for the first time, and we hope they will return. Some left their usual haunts to cover areas (in Washington and Allegany counties) where we were thin on the ground.

As in prior years, a group of DC birders fanned out from Little Orleans, where participant Mary and Steve Huebner’s home is now a registered hostel and a great place to stay, and special thanks are again due to participant Dianne Ingram, NPS naturalist based at the Park headquarters in Sharpsburg, who drove us along the towpath. Participant Diana Cummins and her fellow members of Potomac Valley Audubon Society, as well as members of the Allegany County MOS chapter, were invaluable to this count.

Data Presentation

The spreadsheet for the 2003 count is a 106kb Excel® 2000 file. The file can be found here.It should display with Excel or Microsoft Spreadsheet Works, and other spreadsheet programs. I hope the print format is a little more convenient than in prior years, although there are more pages. It will print legibly on 20 8.5”x11” pages, numbered left to right (ascending mile-segments of the Canal) and then top to bottom (non-passeriforms and passeriforms), plus two pages of summary data for 2003 and earlier years. Pages 1-20 each display a species row, a row with mile numbers, and a row with initials of the reporting principal observer. Column totals are the number of species and numbers of individual birds in a mile-segment. Row totals are, for each species, the total number counted and number of mile-segments in which any were observed. Pages 21 and 22 display totals and comparative aggregate data from 1999-2000-2001-2002. The comments on certain mile-segments are simply text at the bottom of the page, flagged by an asterisk for that mile-segment column.

The mile-segments are numbered starting with “0”, and thus correspond to the milepost marking the downstream endpoint of that sector. This numbering is the least confusing way to report segments covered, and to correlate with the instructions provided to participants, and maps and descriptions in Hahn’s Towpath Guide. The order of species is the same as on the checklist provided to participants.

Quality of the Data and Reporting

Extra independent counts of mile-segments, whether purposeful by a participant’s passing through to another segment or due to miscommunication, produced a lot more species and birds. This is was the case whether or not the counts were close together in time, and is unsurprising, given the mobility of winter foraging-flocks and of most of the non-passerines. As a true population census, this count is not in the ballpark with the survey reported in Hatfield et al., Maryland Birdlife 50:1-4. Since “party-hours” is not a compiled datum, this count is even less normalized in respect of observational effort and opportunity than are the Christmas counts. Like the Christmas counts however, the sheer mass of data, with its limitations understood, will tell a story over time. The appeal of this count, and such internal comparability as it has, derives from its mile-by-mile character.

Obviously some birds appear in different miles and get counted more than once. Only in a few cases can the compiler correct for this with any degree of confidence. Generally, what is reported is what is tabulated, and hopefully double-counted birds make up for missed birds. Nevertheless, recording starting and ending times for each mile-segment, as indicated on the form of checklist, is very helpful. So is noting the time, rough location within the mile-segment, and direction of flight or float for any really large flocks, and any really unusual sightings (plus maturity and sex, if observable.)

More generally, all the information requested on the checklist should be furnished, and I appreciate all those who did so. The species and individual totals are useful as a check against either recording or data-entry errors. Observers’ notes and comments are always interesting and useful for assessment and planning. This year we had comments on mammals seen, … apparent paucity of one or another species or family, and general impressions.)

These remarks from the report on the 2002 count still apply. I also appreciate several helpful comments on access routes to assigned mile-sectors.

Species Comments

As mentioned, it is hard to say what high or low species counts reflect more than random, very local, or day-to-day variability. This would generally be done by comparing the totals for a particular species with those of one or more other species, as a rough control for weather and effort. In 2003, no results seemed that much out of sync with each other. When a real population up down does appear, it is still hard to say whether it has more than short-term significance. This sort of conclusion can only emerge from the accretion of data over the years, with full appreciation of the limiting effect of the lack of standardizing count protocols in our count.

The Ubiquitous Goose was again by far our most abundant species – we’ve retired its uniform so to speak -- and the Conspicuous (or Cawing) Crow was in second place. Carolina Chickadee, White-Throated Sparrow, and Tufted Titmouse occupied the next three slots. Downy Woodpecker and American Crow tied for most widespread (number of mile-sectors), followed very closely by Red-Bellied Woodpecker, tufted Titmouse, and Carolina Wren.

Waterfowl:The Blue Goose of 2000 and 2001 in Mile 97, not observed in 2002, appeared again in Mile 95. Two white-morph Snows and a Tundra Swan were further upstream. Common Merganser numbers were the highest so far for the count, as was the Black Duck–to-Mallard ratio.

Owls: Four Great Horned and eight Barred were welcome highs for the count.

Woodpeckers: No Red-Headed this year, but Pileated was a high for the count.

Phoebe: Nine was a low for the count, possibly because it was a cold winter.

Orange-Crowned Warbler: This species was detected on only two blocks, in Somerset and Baltimore Counties, in the 1988-1993 winter bird survey reported in Hatfield et al., Maryland Birdlife 50:1-4. But I think we were due, as my impression is that single individuals have been seen in mid-winter at the National Arboretum and other fall-line spots in recent years, as well as on the Coastal Plain.

Mike Milton

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