Although Block Island lies just outside of the boundaries of New York State, we hope that our long-term studies of its winter season bird populations might be of interest to birders interested in migration on adjacent Long Island, as well as other parts of New York. Beginning in 1996, a group of birders began bracketing the venerable Block Island CBC with counts in November, around Veterans Day, and in February, around Presidents Day. A major goal of the VDC has been to test our perception that, for many migratory species, abundance reaches low levels in November, only to increase abruptly in December, following the onset of inhospitable conditions to the north. Similarly, a goal of the PDC has been to assess the late-winter survival of the many half-hardy birds recorded each year on the CBC. We chose Block Island because, as a small island, it lacks resident populations of many species that are common on the mainland, making it easier to detect inputs and outputs via directed movements and mortality, but the same methodology can be applied easily anywhere in the region: replicating all or part of one's CBC effort in November and February is likely to be very informative.
Nine observers conducted the 27th annual Block Island Veterans Day Count (VDC)
on 14 November 2022. The weather was clear, with brisk northwesterly winds and
moderate temperatures (38-46 F).
These conditions suggested a potential for the overnight arrival of
nocturnal migrants, but two observers present at the North End at first light
noted just a few small flocks of American Robins and Red-winged Blackbirds
struggling to leave the island. Both of these species (and many others; see
Table 3) were recorded in unusually low numbers this year, and the addition of
80 Robins and 40 Red-wings in morning flight mitigated what would otherwise
have been exceptionally low totals. It often seems that either waterbirds or
landbirds, but not both, will show poorly on a given day, but on this day, low
counts were the rule across most of the checklist. Table 3 shows all species
with totals less than two-thirds their long-term averages. Notably, the
unusually low counts of waterfowl and shorebirds tended to involve species
whose abundance has been trending upward over the 27-year history of the count,
whereas many of the other low counts involved species that have been trending
downward for many years. Among the species with significantly lower than
average totals were no fewer than 16 that average more than 100 individuals per
year. Unsurprisingly, this year’s count of total birds was the lowest ever, at
4,118.
Interestingly, the thicket-inhabiting species whose facultative
early-winter movements have been a major focus of the Block Island winter
counts, were found at low abundance this year. The effort-adjusted metric of
landbirds per party-mile on foot was just 54.4 and would have fallen below the
27-year minimum of 54.1 had it not been for those small flocks of migrating
Robins and Red-wings. Within the thickets, both species of kinglets, Gray
Catbird, White-throated and Song Sparrows, and many others were counted in low
numbers. In many past years we have observed dramatic increases in December
among these species, indicative of post-migratory dispersal, probably in
response to environmental variables such as snow, freezing, and depletion of
food resources.
This year’s worst miss was Cedar Waxwing, which has been missed only
once before on the VDC. It was disappointing to miss species such as American
Pipit, Snow Bunting, Pine Siskin, and Tree Swallow. All of these are erratic on
the VDC but are often numerous when they are present at all. Their absence
across the board contributed to the overall paucity of birds (Table 2). Even
so, the overall species total was 95, which is a very typical number for the
extremely volatile VDC, which unpredictably exceeds 110 or even 120 in
favorable years.
Several unusual species were recorded, but nothing at all surprising,
apart from a distantly seen swallow that was suspected but not confirmed as a
Cave Swallow. Otherwise, two second-ever VDC records involved rapidly
increasing species, Bald Eagle and Common Raven. An off-the-charts tally of 14
Northern Saw-whet Owls came via Scott Comings’ banding work and is not as
surprising as it looks in comparison to our usually hit or miss effort. The
most surprising birds of the day were probably two Northern Parulas foraging
together near Old Harbor (Table 3).
High counts, more than 1.5 times a species’ average, mostly involved
species of low to moderate abundance that have been increasing over time (Table
4). One exception was Ruddy Duck, which has averaged 156 birds per year, but
which came in at an astonishing 640 this year. Four Orange-crowned Warblers
would have been a surprise 20 years ago but not anymore.
I'm not sure of the attached Word file will reach the listserv, so I've pasted
in the tables below to at least show the sets of species mentioned in the
summary above. The formatted summary document and excel spreadsheet are
available on request.
Table 1. Low Counts (less than two-thirds long-term average)
Species count avg max min yrs dev1 trend1
Surf Scoter 1 280 3401 1 27 0.004 3.29
Black Scoter 8 1820 16504 . 26 0.004 32.44
Common Eider 7 538 2112 . 26 0.01 1.87
White-winged Scoter 15 352 4057 4 27 0.04 10.46
Northern Gannet 15 192 1420 2 27 0.08 2.00
Gadwall 1 11 64 . 20 0.09 5.69
American Wigeon 2 17 84 . 22 0.12 4.77
Golden-cr. Kinglet 3 22 101 2 27 0.14 0.33
Slate-colored Junco 18 113 530 5 27 0.16 0.53
Sharp-shinned Hawk 1 6 15 . 26 0.16 0.62
Red-throated Loon 5 28 292 . 26 0.18 0.37
Great Cormorant 11 59 175 7 27 0.19 1.33
Common Loon 16 73 350 9 27 0.22 0.61
Northern Flicker 12 49 125 5 27 0.25 0.43
Savannah Sparrow 2 7 29 . 25 0.28 0.57
Herring Gull 271 964 2863 267 27 0.28 1.39
Field Sparrow 1 3 12 . 23 0.30 0.53
Northern Mockingbird 5 16 45 . 26 0.31 0.37
Dunlin 2 6 16 . 26 0.34 2.10
Myrtle Warbler 126 346 1431 23 27 0.36 0.26
Red-br. Merganser 94 246 895 35 27 0.38 0.33
Swamp Sparrow 9 22 82 2 27 0.40 0.51
American Crow 93 222 500 66 27 0.42 0.80
Black-bellied Plover 16 37 99 6 27 0.43 1.86
Laughing Gull 6 14 72 1 27 0.44 1.25
House Sparrow 44 100 303 10 27 0.44 1.52
Blue Jay 13 30 58 5 27 0.44 0.83
Gray Catbird 10 23 70 2 27 0.44 0.78
Great Blue Heron 4 9 67 . 26 0.44 0.44
Ruby-cr. Kinglet 5 11 47 1 27 0.45 0.93
Merlin 1 2 6 . 24 0.47 0.84
Green-winged Teal 5 11 67 . 24 0.47 1.30
Ring-neck Pheasant 11 23 60 4 27 0.48 0.52
Great Black-back Gull 301 604 2500 192 27 0.50 0.66
Greater Yellowlegs 3 6 37 . 24 0.50 0.50
American Black Duck 27 54 114 8 27 0.50 0.99
American Robin 193 381 1188 39 27 0.51 0.48
Palm Warbler 3 6 32 . 23 0.54 0.28
European Starling 358 637 1367 108 27 0.56 0.72
Song Sparrow 160 274 434 50 27 0.58 0.89
Red-winged Blackbird 90 83 644 1 27 0.60 0.24
White-thr. Sparrow 136 211 577 43 27 0.65 0.49
Table 2. Worst Misses (species recorded on 10 or more VDCs).
Species yrs avg max
Cedar Waxwing 26 69 221
Pied-billed Grebe 23 2 8
Belted Kingfisher 21 2 7
Brown-headed Cowbird 21 13 73
White-crowned Sparrow 20 3 21
American Pipit 19 11 77
Common Yellowthroat 19 1 8
Chipping Sparrow 17 5 47
Snow Bunting 17 31 511
Common Grackle 17 9 140
Brown Creeper 16 1 6
Wilson's Snipe 14 1 5
Eastern Phoebe 14 1 6
Ipswich Sparrow 13 1 8
Eastern Meadowlark 13 3 23
Pine Siskin 13 28 186
Brant 12 1 4
Common Goldeneye 12 1 4
Pine Warbler 12 2 25
Horned Grebe 11 2 22
Bonaparte's Gull 11 3 31
Hairy Woodpecker 11 1 11
Lesser Scaup 10 1 10
Red-necked Grebe 10 1 3
American Woodcock 10 1 8
Yellow-bellied Sapsucker 10 1 4
Blue-headed Vireo 10 0 2
Tree Swallow 10 11 189
Blackpoll Warbler 10 1 5
Yellow-breasted Chat 10 0 2
American Tree Sparrow 10 2 13
Table 3. Unusual Species (recorded on fewer than ten VDCs)
Species count yrs max comments
Greater Scaup 3 9 8
Bald Eagle 1 2 1
Red-tailed Hawk 1 6 2
American Kestrel 1 8 2
Northern Saw-whet Owl 14 6 14 banded
Common Raven 4 2 4
Swallow sp. 1 2 1 probably Cave
Northern Parula 2 3 2
Lincoln's Sparrow 1 7 2
Table 4. High Counts (more than 1.5 times long-term average)
Species count avg max min yrs dev1 trend2
Ruddy Duck 640 156 640 17 27 4.10 1.22
Rock Pigeon 35 12 40 . 19 3.03 5.93
Marsh Wren 2 1 2 . 13 2.84 0.55
Orange-crowned Warbler 4 1 6 . 19 2.84 1.43
Great Egret 10 4 11 . 20 2.81 3.30
White-breasted Nuthatch 5 2 8 . 16 2.65 2.54
Black-crowned Night Heron 3 1 13 . 10 2.45
1.00
Ring-necked Duck 78 34 78 . 25 2.32 1.85
Peregrine Falcon 2 1 4 . 14 2.25 2.67
American Coot 26 13 89 . 25 2.06 1.53
Virginia Rail 5 3 7 . 21 1.85 1.34
Sanderling 61 34 93 3 27 1.80 1.65
Red-bellied Woodpecker 7 4 27 . 24 1.56 2.93
1 dev measures the deviation of this year’s count from expectation and is
calculated by dividing each species’ count by its long-term average on the VDC.
2 trend measures change in abundance over the 27-year history of the VDC and is
calculated by dividing each species’ average count over the past 13 years
(2009-2021) by its average over the prior 13 years (1996-2008).
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BI VDC 123 Summary.docx
Description: BI VDC 123 Summary.docx
