Environmental and Social Research

John F. Kearney & Associates

METADATA

Microphone: SMX-NFC

<Sampling format; 16 bit

<Sampling rate: 24,000 Hz

Recording Equipment: Song Meter 2

Analysis Software: Raven Pro

High Frequency Detector Settings

>6000-11000 Hz, 23-395 ms,

>Signal/Noise 25% Minimum Occupancy

>Signal/Noise Ratio Threshold 3.5 dB

>Block Size 4992 ms, Hop Size 244 ms, 50%

Low Frequency Detector Settings

>2250-3750 Hz, 35-325 ms,

>Signal/Noise 20% Minimum Occupancy

>Signal/Noise Ratio Threshold 4.0 dB

>Block Size 998 ms, Hop Size 244 ms, 50%
Nocturnal Migration 2017

Cape Forchu, Yarmouth County, Nova Scotia

Weekly Reports at Cape Forchu for the Autumn 2017



2ndWeek of October


Nocturnal migration made a comeback this week at this coastal site with an impressive movement of Yellow-rumped Warblers. A total of 936 night flight calls representing an estimated 416 birds was recorded. The next most common migrants were White-throated Sparrow with 163 calls, Palm Warbler (143), and Savannah Sparrow (117).


Great Blue Herons migrate more at night in Nova Scotia than I had previously thought. Their total numbers rose to an estimated 31 birds this week.


The lateness of the Swainson’s Thrush migration continues to amaze with another 60 calls this week representing an estimated 37 birds. There were also 25 Hermit Thrush night flight calls.


Shorebirds recorded this week included Black-bellied Plover (4 estimated birds), Pectoral Sandpiper (3), and Dunlin (1).


Late warblers consisted of a Bay-breasted Warbler on 11 October at 22:05 hours and a Cape May Warbler on 12 October at 19:20 hours.


Other less common birds included a Dickcissel on 11 October at 06:57 hours.


A summary table is given below.




Estimated

Species

Calls

Birds

Yellow-rumped Warbler

936

416

White-throated Sparrow

163

95

Palm Warbler

143

93

Savannah Sparrow

117

76

Common Yellowthroat

93

57

Great Blue Heron

80

31

Northern Parula

65

42

Swainson's Thrush

60

37

Nashville Warbler

40

28

Unidentified Warbler

32

27

Blackpoll Warbler

28

24

Hermit Thrush

25

11

Unidentified Sparrow

18

16

Magnolia Warbler

17

15

Chipping Sparrow

13

8

Black-bellied Plover

12

4

Cedar Waxwing

12

5

Black-throated Blue Warbler

11

9

Unidentified Songbird

11

10

Song Sparrow

11

8

Black-and-White Warbler

8

7

Black-throated Green Warbler

8

7

Pectoral Sandpiper

8

3

Rose-breasted Grosbeak

8

6

Lincoln's/Swamp Sparrow

6

6

Golden-crowned Kinglet

4

3

Ovenbird

4

3

American Redstart

3

3

American Robin

3

1

Greater Yellowlegs

3

1

Wilson's Warbler

2

2

Bay-breasted Warbler

1

1

Cape May Warbler

1

1

Chestnut-sided Warbler

1

1

Dickcissel

1

1

Dunlin

1

1

Nelson's Sparrow

1

1

Orange-crowned Warbler

1

1

Total

1,951

1,061

 





1stWeek of October


Nocturnal again declined this week, falling by 83% from the previous week. In all, 380 night flight calls representing an estimated 271 birds were recorded. This is close to the same volume of migration as at the inland site in Carleton during this week.


The top four species in abundance were Yellow-rumped Warbler (78 calls), Savannah Sparrow (56), Swainson’s Thrush (50), and Blackpoll Warbler (43). While relatively low in comparison to earlier weeks, the number of Swainson’s Thrushes is higher than normal for this late in the autumn season.


The equality of numbers between the inland and coastal sites this week may indicate that, as radar studies have suggested in the past, birds have started taking a more westerly route (rather than southwest) to avoid bad weather over the Gulf of Maine and instead favour a shorter route over the Bay of Fundy. Next week should reveal more in this regard.


There were no rare birds this week.


A summary table is below.




Estimated

Species

Calls

Birds

Yellow-rumped Warbler

78

53

Savannah Sparrow

56

38

Swainson's Thrush

50

29

Blackpoll Warbler

43

33

Common Yellowthroat

19

14

Magnolia Warbler

14

11

Palm Warbler

14

13

White-throated Sparrow

14

12

Nashville Warbler

12

9

Northern Parula

11

7

Unidentified Shorebird

7

5

Hermit Thrush

6

3

Sanderling

6

2

Unidentified Songbird

5

5

American Pipit

4

3

Black-throated Green Warbler

4

4

Greater Yellowlegs

4

1

Unidentified Warbler

4

4

Rose-breasted Grosbeak

4

3

Black-and-White Warbler

3

2

Chestnut-sided Warbler

3

3

Great Blue Heron

3

2

Lincoln's/Swamp Sparrow

3

2

Chipping Sparrow

2

2

Unidentified Sparrow

2

2

Unidentified Warbler Genus Oreothlypis

2

2

Ovenbird

2

2

American Redstart

1

1

Black-throated Blue Warbler

1

1

Golden-crowned Kinglet

1

1

Orange-crowned Warbler

1

1

Semipalmated Plover

1

1

Total

380

271

 



4thWeek of September


Nocturnal migration declined appreciably during the 4thweek of September at Cape Forchu. Whereas the previous week had an average of 1,357 calls per night, this week had an average of only 282 calls per night. However, despite this steep decline there were still more migrants over Cape Forchu than inland at Carleton which average 155 calls per night.


An interesting similarity between the two sites was the dominance of the late-migrating Yellow-rumped Warbler and Palm Warbler. Noteworthy differences were the lack of a sparrow presence at Cape Forchu compared to Carleton, and a continuing migration of Swainson’s Thrushes at Cape Forchu but not Carleton. Carleton, on the other hand, did record increasing numbers of Hermit Thrushes.


One might surmise from these differences that the Yellow-rumped Warbler, Palm Warbler, and Swainson’s Thrush were exiting the province this week while sparrows and Hermit Thrushes were arriving from points further north into stop-over habitat.


Rare or less common birds for the week included 6 Orange-crowned Warblers, 5 Gray-cheeked Thrushes, and 1 Indigo Bunting. In total this autumn at Cape Forchu, 22 Gray-cheeked Thrush calls have been recorded for an estimated total of 16 birds.


A summary table for the week is given below.

 



Estimated

Species

Calls

Birds

Palm Warbler

297

195

Yellow-rumped Warbler

278

179

Common Yellowthroat

253

175

Magnolia Warbler

168

119

Blackpoll Warbler

161

111

Northern Parula

144

97

Swainson's Thrush

142

86

Black-and-White Warbler

140

98

Savannah Sparrow

110

90

American Redstart

57

46

White-throated Sparrow

51

39

Black-throated Green Warbler

49

38

Nashville Warbler

48

36

Chestnut-sided Warbler

47

33

Unidentified Warbler

46

42

Cape May Warbler

39

25

Ovenbird

35

30

Blackburnian Warbler

25

17

Lincoln's/Swamp Sparrow

21

19

Great Blue Heron

16

4

Wilson's Warbler

14

13

Hermit Thrush

11

6

Bay-breasted Warbler

9

8

Gray-cheeked Thrush

8

5

Northern Waterthrush

8

8

Tennessee Warbler

8

5

Black-throated Blue Warbler

7

7

Orange-crowned Warbler

7

6

Unidentified Warbler Genus Oreothlypis

7

7

Unidentified Sparrow

6

6

Unidentified Songbird

6

6

Golden-crowned Kinglet

5

3

Unidentified Warbler Genus Setophaga

5

4

Song Sparrow

5

3

Yellow Warbler

5

4

Mourning Warbler

4

4

Semipalmated Plover

2

2

Veery

2

2

Bobolink

1

1

Canada Warbler

1

1

Indigo Bunting

1

1

Nelson's Sparrow

1

1

Rose-breasted Grosbeak

1

1

Semipalmated Sandpiper

1

1

Total

2,252

1,584

 



3rdWeek of September


 

Acoustic recording of nocturnal migration at Cape Forchu this week revealed a massive exit of passerines from the province of Nova Scotia this week. Total calls recorded were 9,496 which represent an estimated minimum of 5,156 birds. This weekly total exceeds the total calls recorded at many stations elsewhere in Nova Scotia during an entire autumn season in previous years. In addition, the estimated birds are very likely too low since my estimation technique tries to account for individual birds that call multiple times while passing over the microphone. However, the flight of birds was so dense on some nights that calls of the same species within a couple of milliseconds of each other were a frequent occurrence. These are obvious two birds but the estimation technique would list them as one.


While further analysis would be required, the first examination of results indicates that the vast majority of birds were recorded early in the night, from 21:00 to 23:30 hours. This indicates that birds were leaving the Cape Forchu area or within a couple hours of flying distance from that location. This was notably true as well for thrushes for which the majority are normally heard during the descent phase of their flight, in the ninety minutes before dawn.


The first two nights of this week, the nights beginning on 15 and 16 September, were dominated by the migration of thrushes.  On each of these nights, 454 Swainson’s Thrush calls were recorded. There were also 62 Veeries, 13 Hermit Thrushes, and 12 Gray-cheeked Thrush calls on these two nights combined (estimated 9 individual Gray-cheeked Thrushes).


The peak night of the week for all species was the night beginning on 18 September. On this night, 4,048 calls were recorded with the most common species being Common Yellowthroat (775 calls), Northern Parula (759), Magnolia Warbler (442), Ovenbird (288), and Black-and-White Warbler (222).


There was also a strong flight of Savannah Sparrows (estimated 213 birds) and Solitary Sandpipers (estimated 42 birds) during this week.


Rare or less common birds recorded included 9 Gray-cheeked Thrushes (individual birds), 8 Prairie Warblers, 4 Pine Warblers, 3 Dickcissels, 3 Orange-crowned Warblers, 2 Scarlet Tanagers, 1 Vesper Sparrow, 1 Stilt Sandpiper, and 1 Blue-winged/Golden-winged Warbler.


A summary table for the week is given below.

 



Estimated

Species

Calls

Birds

Common Yellowthroat

1,496

679

Northern Parula

1,339

566

Swainson's Thrush

1,098

485

Magnolia Warbler

796

419

Ovenbird

535

299

Black-and-White Warbler

531

337

Chestnut-sided Warbler

350

208

American Redstart

349

228

Savannah Sparrow

340

213

Cape May Warbler

332

184

Unidentified Warbler

249

184

Blackpoll Warbler

226

157

Black-throated Blue Warbler

203

118

Nashville Warbler

187

124

Solitary Sandpiper

164

42

Palm Warbler

151

103

Northern Waterthrush

148

95

Yellow Warbler

130

87

Black-throated Green Warbler

125

85

Bay-breasted Warbler

122

83

Yellow-rumped Warbler

88

70

Blackburnian Warbler

81

64

Veery

72

39

Unidentified Warbler Genus Setophaga

63

56

Semipalmated Sandpiper

54

23

Wilson's Warbler

42

38

Semipalmated Plover

23

12

Mourning Warbler

22

21

Bobolink

21

14

Canada Warbler

21

16

Tennessee Warbler

16

13

Hermit Thrush

15

10

White-throated Sparrow

15

13

Gray-cheeked Thrush

12

9

Lincoln's/Swamp Sparrow

11

10

Unidentified Songbird

10

10

Prairie Warbler

10

8

Pine Warbler

8

4

Great Blue Heron

5

5

Nelson's Sparrow

5

4

Orange-crowned Warbler

5

3

Scarlet Tanager

4

2

Chipping Sparrow

3

1

Dickcissel

3

3

Rose-breasted Grosbeak

3

3

Spotted Sandpiper

3

1

Vesper Sparrow

3

1

Unidentified Warbler Genus Oreothlypis

2

2

Black-bellied Plover

1

1

Unidentified Sparrow

1

1

Song Sparrow

1

1

Stilt Sandpiper

1

1

Unidentified Warbler Genus Vermivora

1

1

Total

9,496

5,156

 



 

2ndWeek of September



The first four nights of this week were characterized by intense nocturnal migration at Cape Forchu, Yarmouth County. Total night flight calls were 1,478 on the night beginning on 8 September, 1,645 on 9 September, 837 on 10 September, and 1,134 on 11 September. On the last three days of the week migration declined to a trickle.


On the first night of this intense migration after the slow 1stweek of September, the most common warblers were Bay-breasted Warbler with 178 calls and an estimated 98 individual birds and Cape May Warbler with 169 calls and an estimated 91 birds. This appears to have been the climax of an extraordinary number of these two species in the early autumn migration of 2017. After this night, their numbers declined considerably.


The weekly total was 5,319 flight calls representing an estimated 3,321 birds. The most common birds for the entire week were Common Yellowthroat (762 calls), Black-and-White Warbler (548), Swainson’s Thrush (492), American Redstart (476), Northern Parula (385), and Magnolia Warbler (348).


Bobolinks increased to 90 night flight calls and an estimated 60 birds. The most common sparrow was Savannah Sparrow with 160 calls, Semipalmated Sandpipers and Semipalmated Plovers were the most common shorebirds with 64 and 63 calls respectively. Besides the heavy migration of Swainson’s Thrush, there were 47 Veery calls.


Rare or less common birds for the week included an estimated 4 Prairie Warblers, 1 Upland Sandpiper (11 September at 22:56 hours), 1 Scarlet Tanager (9 September at 06:03 hours), 1 Gray-cheeked Thrush (12 September at 01:46 hours), and 1 Orange-crowned Warbler (14 September at 01:06 hours).


A summary table for the week is provided below.




Estimated

Species

Calls

Birds

Common Yellowthroat

762

412

Black-and-White Warbler

548

333

Swainson's Thrush

492

271

American Redstart

476

273

Northern Parula

385

227

Magnolia Warbler

348

224

Bay-breasted Warbler

290

185

Cape May Warbler

265

160

Savannah Sparrow

160

106

Northern Waterthrush

146

103

Chestnut-sided Warbler

125

89

Unidentified Warbler

109

97

Nashville Warbler

107

74

Yellow Warbler

105

71

Black-throated Green Warbler

104

82

Bobolink

90

60

Wilson's Warbler

84

76

Blackpoll Warbler

70

55

Semipalmated Sandpiper

64

34

Semipalmated Plover

63

37

Ovenbird

50

42

Veery

47

28

Blackburnian Warbler

43

33

Yellow-rumped Warbler

43

35

Mourning Warbler

38

27

Black-throated Blue Warbler

31

24

Great Blue Heron

28

5

Palm Warbler

25

16

Greater Yellowlegs

24

4

Unidentified Warbler Genus Setophaga

24

23

Tennessee Warbler

24

18

Unidentified Shorebird

21

15

Unidentified Songbird

17

14

Canada Warbler

16

14

Hermit Thrush

16

10

Unidentified Flycatcher

14

1

Least Sandpiper

11

6

White-throated Sparrow

9

9

Prairie Warbler

7

4

Upland Sandpiper

7

1

Unidentified Warbler Genus Oreothlypis

6

6

Unknown Bird

5

1

Dark-eyed Junco

4

1

Unidentified Sparrow

4

4

Lincoln's/Swamp Sparrow

4

4

Scarlet Tanager

2

1

Cedar Waxwing

1

1

Gray-cheeked Thrush

1

1

Orange-crowned Warbler

1

1

Rose-breasted Grosbeak

1

1

Ruddy Turnstone

1

1

Song Sparrow

1

1

Total

5,319

3,321




1stWeek of September


 

Nocturnal migration over Cape Forchu, Yarmouth County, was down to 1/8 of the traffic from the previous week. Only the night of 2-3 September showed moderate migration with a total of 425 calls. On this night surface winds and winds at 1,500 meters altitude were from the north. Following this night winds were varied between southeast and southwest. Thus, calls on the next four days of the week ranged between 4 and 36 with a total for the entire seven days of 556. This represented an estimated 378 birds

.

The most common bird of the week was Swainson’s Thrush with 106 calls and an estimated 56 birds.


Rare or less common birds for the week included American Golden-Plover (2 September at 06:10 hours), Long-billed Dowitcher (7 September at 03:32), and Prairie Warbler (3 September at 03:11).


A data summary for the week is presented in the table below.




Estimated

Species

Calls

Birds

Swainson's Thrush

106

56

Black-and-White Warbler

44

30

Bay-breasted Warbler

33

26

Magnolia Warbler

30

26

Savannah Sparrow

37

26

Semipalmated Plover

44

25

Cape May Warbler

33

23

American Redstart

23

16

Northern Waterthrush

21

15

Semipalmated Sandpiper

27

15

Yellow Warbler

15

15

Wilson's Warbler

15

12

Veery

15

10

Nashville Warbler

11

8

Northern Parula

10

8

Unidentified Warbler

9

8

Chestnut-sided Warbler

11

7

Black-throated Green Warbler

9

6

Common Yellowthroat

6

5

Blackpoll Warbler

5

4

Bobolink

4

4

Great Blue Heron

10

4

Blackburnian Warbler

3

3

Black-throated Blue Warbler

3

3

Canada Warbler

3

3

Mourning Warbler

3

3

Ovenbird

3

3

Song Sparrow

7

3

Yellow-rumped Warbler

5

3

Tennessee Warbler

4

2

American Golden-Plover

1

1

Long-billed Dowitcher

1

1

Unidentified Warbler Genus Oreothlypis

1

1

Prairie Warbler

1

1

White-throated Sparrow

2

1

Yellow-bellied Flycatcher

1

1

Total

556

378

 



4thWeek of August


 

Nocturnal migration over Cape Forchu, Yarmouth County, was very heavy for the last ten days of August. A total of 4,445 night flight calls representing an estimated 2,806 birds were recorded. This is over 3 times the number of calls recorded at the inland location at Carleton, Yarmouth County, over the same period. Among the top six species recorded were Northern Waterthrush (428 calls), Cape May Warbler (339 calls), Wilson’s Warbler (333 calls), and Bay-breasted Warbler (257 calls). These three species are normally among the less abundant warblers at this time of year.


In addition, Canada Warblers (an “endangered” species in Nova Scotia) were recorded 90 times for an estimated 67 individual birds. Overall this station has detected a total of 246 calls and an estimated 192 birds of this species in the month of August.


The high numbers of Cape May and Bay-breasted Warblers may be a consequence of the Spruce Budworm outbreak in the northern boreal forest. These two species along with Tennessee Warbler are considered to be Spruce Budworm dependent species. While the number of Tennessee Warblers has not exploded, they are nonetheless higher than in previous years. The relatively wet summer may account for the high numbers of Northern Waterthrush, Canada Warbler, and Wilson’s Warbler; species that prefer moist breeding habitats.


The most common bird recorded in this last week of August was the American Redstart with 539 calls and an estimated 331 individuals. The migration of Catharus thrushes also began in earnest this week with the recording of 92 calls of the Swainson’s Thrush, 58 of the Veery, and 4 of the Hermit Thrush. These are normal for Swainson’s and high for Veery while Hermit Thrush peak much later in September and early October. There were also good numbers recorded of Bobolinks; an estimated 41 birds and a species regarded as “vulnerable” in Nova Scotia.


Peak nights were on 24-25 August (1,228 calls), 26-27 August (866 calls), 27-28 August (744 calls), and 31 August-1 September (690 calls). At the end of the three heaviest nights there were pre-dawn fallouts of a smaller variety of species, mainly Northern Waterthrush, Bay-breasted Warblers, Cape May Warblers, Yellow Warblers, and Blackburnian Warblers.


Rare or uncommon birds included Prairie Warbler (2 on 28 August at 01:04 and at 01:16), Cedar Waxwing (1st time I’ve recorded this species in nocturnal migration – 1 September 00:52), White-crowned Sparrow (1 September 02:44), and Wood Thrush (24 August at 23:05).


A summary of the activity for the 4th week of August is given in the table below.




Estimated

Species

Calls

Birds

American Redstart

539

331

Northern Waterthrush

428

266

Black-and-White Warbler

412

264

Wilson's Warbler

333

203

Cape May Warbler

339

191

Bay-breasted Warbler

257

170

Magnolia Warbler

233

159

Common Yellowthroat

214

148

Yellow Warbler

225

144

Unidentified Warbler

134

118

Chestnut-sided Warbler

139

89

Canada Warbler

90

67

Savannah Sparrow

101

66

Swainson's Thrush

92

55

Ovenbird

70

54

Semipalmated Plover

102

53

Blackburnian Warbler

74

50

Northern Parula

73

48

Bobolink

73

41

Tennessee Warbler

52

39

Veery

58

35

Black-throated Green Warbler

41

32

Semipalmated Sandpiper

65

31

Unidentified Warbler Genus Setophaga

23

21

Yellow-rumped Warbler

25

19

Blackpoll Warbler

26

18

Nashville Warbler

29

18

Black-throated Blue Warbler

17

14

Great Blue Heron

87

10

Mourning Warbler

11

9

Dark-eyed Junco

23

8

Least Sandpiper

6

6

Unidentified Shorebird

11

3

Unidentified Warbler Genus Oreothlypis

3

3

Palm Warbler

4

3

White-throated Sparrow

3

3

Alder Flycatcher

3

2

Hermit Thrush

4

2

Unidentified Songbird

3

2

Prairie Warbler

2

2

Rose-breasted Grosbeak

6

2

Spotted Sandpiper

3

2

Cedar Waxwing

1

1

Greater Yellowlegs

8

1

Lesser Yellowlegs

1

1

White-crowned Sparrow

1

1

Wood Thrush

1

1

Total

4,445

2,806



3rdWeek of August

 

There were two significant flights during the third week of August (the evening of 15 August to the morning of 22 August) at the Cape Forchu acoustic monitoring station. The first was the night of 17-18 August with 500 night flight calls. The second was the night of 20-21 August with 578 night flight calls. Overall for the week, 1,387 night flight calls representing an estimated 927 birds were recorded. The number of night flight calls were double those recorded at the inland recording station at Carleton during this same week. The flights at Cape Forchu were dominated by American Redstarts (185 calls), Northern Waterthrush (157), Magnolia Warbler (142), Yellow Warbler (124), and Black-and-white Warbler (104). Surprising numbers of Canada Warblers continued into this week with 81 calls and an estimated 69 birds.


The difference in species composition between the coastal and inland stations may provide some insight into migration patterns in southwest Nova Scotia. At Cape Forchu, Northern Waterthrushes comprised 12.9% of the warblers recorded with Canada Warbler accounting for 6.7% of warbler detections. At Carleton, warbler detections consisted of 4.5% of Northern Waterthrushes and 2.6% of Canada Warblers. In contrast, Ovenbirds made up 7% of the warblers at Carleton and 0.5% at Cape Forchu, and Northern Parulas were 8.5% of warblers at Carleton compared to 1.2% at Cape Forchu. These numbers suggest that some warblers have a more coastal route, others an inland route, and still others fly on a broad front.


The data at Cape Forchu suggest that it is a departure point for birds leaving Nova Scotia to cross the Gulf of Maine. Recordings times show that 68% of the birds at Cape Forchu were detected in the first four hours after civil sunset compared to 57% at Carleton. Thus Carleton would appear to have a more equal aerial distribution of departing and arriving birds.


Rare or unusual birds for the week included Gray-cheeked Thrush and a Vermivora warbler, either Golden-winged or Blue-winged (not yet known to be distinguishable by flight call).


A summary for the week is provided in the table below.

 



Estimated

Species

Calls

Birds

American Redstart

185

117

Northern Waterthrush

157

106

Magnolia Warbler

142

96

Yellow Warbler

124

82

Black-and-White Warbler

104

76

Canada Warbler

81

69

Common Yellowthroat

88

53

Chestnut-sided Warbler

74

48

Blackpoll Warbler

53

37

Unidentified Warbler

38

31

Semipalmated Plover

62

28

Blackburnian Warbler

32

26

Cape May Warbler

41

26

Unidentified Warbler Genus Setophaga

21

21

Savannah Sparrow

21

13

Semipalmated Sandpiper

30

13

Black-throated Green Warbler

21

12

Great Blue Heron

29

10

Northern Parula

14

10

Bay-breasted Warbler

12

9

Ovenbird

6

6

White-throated Sparrow

13

6

Yellow-rumped Warbler

7

6

Bobolink

4

4

Black-throated Blue Warbler

4

3

Least Sandpiper

4

3

Nashville Warbler

4

3

Unidentified Songbird

3

3

Unidentified Duck

1

1

Gray-cheeked Thrush

1

1

Lesser Yellowlegs

2

1

Lincoln's/Swamp Sparrow

1

1

Mourning Warbler

1

1

Unidentified Warbler Genus Oreothlypis

3

1

Palm Warbler

1

1

Unidentified Tern

1

1

Veery

1

1

Unidentified Warbler Genus Vermivora

1

1

Total

1,387

927

 



2nd Week of August


The new Cape Forchu monitoring station provided some evidence this week that it is well situated for detecting nocturnal migration at this coastal location. A total of 758 calls and an estimated 488 birds were recorded in this seven-day period. As with the inland site at Carleton, American Redstarts dominated the composition of the nightly flights with 134 calls and an estimated 28 birds. Yellow Warblers, Black-and-White Warblers, and Northern Waterthrushes were also common. Most surprising was the flight of an estimated 35 Canada Warblers on the night of 11 to 12 August (with 52 flight calls).


Echo densities on the Caribou, Maine, weather radar were up in the range of 71 per square kilometer this week compared to 59 in the previous week.


The most uncommon bird detected this week was a Prairie Warbler at 0020 hours on 15 May.


A summary of the week’s nocturnal migration is below.




Estimated

Species

Calls

Birds

American Redstart

134

88

Yellow Warbler

91

66

Black-and-White Warbler

84

61

Canada Warbler

73

54

Northern Waterthrush

54

41

Chestnut-sided Warbler

38

28

Magnolia Warbler

42

27

Least Sandpiper

30

16

Semipalmated Plover

30

15

Unidentified Warbler

15

13

Savannah Sparrow

16

10

Unidentified Tern

51

10

Blackburnian Warbler

11

9

Semipalmated Sandpiper

9

8

Ovenbird

9

6

Unidentified Warbler Genus Setophaga

6

6

Blackpoll Warbler

5

4

Nashville Warbler

6

4

Bay-breasted Warbler

3

3

Common Yellowthroat

6

3

Northern Parula

4

3

Black-throated Blue Warbler

2

2

Unidentified Songbird

2

2

Spotted Sandpiper

29

2

Unidentified Shorebird

1

1

Dark-eyed Junco

1

1

Lesser Yellowlegs

2

1

Palm Warbler

1

1

Prairie Warbler

1

1

Swainson's Thrush

1

1

Yellow-rumped Warbler

1

1

Total

758

488



1st Week of August

 

This is the first report from the new Cape Forchu nocturnal migration acoustic monitoring station. The monitoring station is only a few meters from the coast.


There was a total of 166 flight calls recorded, representing an estimated 58 birds and 17 species. The most common species was unidentified terns. My initial searches of various flight call libraries would indicate that the calls were those of the Common Tern. It was estimated that the 91 tern calls recorded on the night of 4 August just after nightfall represented 12 birds. This is a conservative estimate that assumed birds were circling the station. However, since Common Terns begin their overwater migration just after sunset, it is possible the calls represent a higher number, perhaps up to 30, birds streaming past the station.


The most common land birds were Northern Waterthrush, Black-and-White Warbler, and American Redstart. The relatively few warblers at this coastal site contrasts with a considerably higher number at the Carleton station which is 30 km inland from Cape Forchu. This would suggest that inland areas provide more favourable stopover habitat in the early stages of migration and during post-fledgling dispersal.


However, two other factors may affect a comparison of these two sites. First, the Cape Forchu recording unit runs on battery power which results in an estimated 1/3 reduction in the power and reach of the microphone compared to the electric cord power source of the recording unit at Carleton. Second, it will take the better part of the migration season to determine if the recording unit at Cape Forchu is optimally located in relation to the local migratory pathways in the area.


A summary of the week’s nocturnal migration is summarized in the table below.




Estimated

Species

Calls

Birds

Unidentified Tern

91

12

Northern Waterthrush

13

10

Black-and-White Warbler

10

8

American Redstart

11

7

Blackpoll Warbler

5

3

Least Sandpiper

5

3

Magnolia Warbler

4

3

Canada Warbler

2

2

Unidentified Shorebird

4

2

Unidentified Warbler

2

2

Semipalmated Plover

2

2

Semipalmated Sandpiper

4

2

Yellow Warbler

3

2

Alder Flycatcher

1

1

Blackburnian Warbler

1

1

Chestnut-sided Warbler

1

1

Ovenbird

1

1

Spotted Sandpiper

5

1

Tennessee Warbler

1

1

Total

166

58

 

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