Environmental and Social Research

John F. Kearney & Associates

Weekly Reports for Carleton, Yarmouth County, 2015 (N43.9967, W65.9159)



Link to Summary Table


Link to Table of Peak Counts

METADATA

Microphone: Old Bird 21c

<Sampling format; 16 bit

<Sampling rate: 22,050 Hz

Recording Equipment: Laptop Computer

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%







Week of November 16-22


The last week of recording the flight calls of nocturnal migrants over Carleteon, Yarmouth County, was the period of November 16-22. A total of 8 flight calls, representing 8 separate birds was recorded. White-throated Sparrows accounted for 7 of the calls and the other was from an American Tree Sparrow. A summary table is below. Compared to other sites, the Carleton monitoring station had a high proportion of warblers and low proportions of sparrows and thrushes.

 



Estimated


Total

Minimum

Species

Calls

Individuals

White-throated Sparrow

7

7

American Tree Sparrow

1

1

Total

8

8


Week of November 9-15


Nocturnal migration over Carleton, Yarmouth County, is showing signs of winding down. Total calls this week numbered 82, representing an estimated minimum number of 35 birds. The most common call this week was that of the Dark-eyed Junco at 47. All of these Juncos were heard in a 46 minute period early in the night and may have represented a group or groups of local birds departing. The next most common call was White-throated Sparrow at 11 calls. All other birds were seasonably appropriate with no rare birds noted. It was the first week without a warbler being recorded. A summary table follows.

 



Estimated


Total

Minimum

Species

Calls

Individuals

Dark-eyed Junco

47

7

White-throated Sparrow

11

10

Unidentified Sparrow

6

6

Pine Siskin

6

1

Song Sparrow

5

5

Boreal Chickadee

2

2

Lincoln's/Swamp Sparrow

2

1

Unidentified Songbird

2

2

Fox Sparrow

1

1

Total

82

35


Week of November 2-8


Nocturnal migration over Carleton, Yarmouth County, during the first week of November was up somewhat from the last week of October. Total calls increased from 74 to 116 and estimated minimum individuals from 55 to 95. For the fifth week in a row, White-throated Sparrow was the most common species with 52 calls. Song Sparrow was next with 11 calls. A number of species were recorded in nocturnal migration at this site for the first time during this week; Pine Siskin (3 calls), American Robin (2), Nelson’s Sparrow (2), and Brown Creeper (1). The spectrogram of a distant sparrow call resembled Grasshopper Sparrow. Late warblers included one unidentified, 3 Yellow-rumped Warblers, and 1 Pine Warbler. The Pine Siskin, normally a diurnal migrant, was recorded 51 minutes before sunrise on the morning of November 9th. A summary table follows.

 



Estimated


Total

Minimum

Species

Calls

Individuals

White-throated Sparrow

52

40

Song Sparrow

11

11

Dark-eyed Junco

6

2

Unidentified Sparrow

6

6

Savannah Sparrow

6

6

Chipping Sparrow

5

3

Fox Sparrow

5

6

Unidentified Songbird

5

4

Lincoln's/Swamp Sparrow

4

4

Pine Siskin

3

1

Yellow-rumped Warbler

3

3

American Robin

2

1

Nelson's Sparrow

2

2

American Tree Sparrow

1

1

Boreal Chickadee

1

1

Brown Creeper

1

1

Grasshopper Sparrow

1

1

Unidentified Warbler

1

1

Pine Warbler

1

1

Total

116

95


Week of October 26-November 1


Nocturnal migration over Carleton, Yarmouth County, continued in small numbers this week but with some interesting results. Overall, 74 flight calls representing an estimated minimum of 55 birds were recorded. The most common bird was again White-throated Sparrow (17 calls), followed by Golden-crowned Kinglet (16), Yellow-rumped Warbler (6), Dark-eyed Junco (5), and Song Sparrow (5). It was the first week this autumn without a Common Yellowthroat. The first definite winter bird of the season was an American Tree Sparrow on the night of October 30th. Although Blue-headed Vireos do not give night flight calls, the “scolding call” of one was recorded at 6:03 am (AST) on November 1st, or about one hour before sunrise. A long, low-pitched (for a sparrow) call recorded at 10:11 pm on November 1st was very possibly a Seaside Sparrow. Both the spectrogram and the recorded sound were a good fit for this species. As always, a summary table follows.

 



Estimated


Total

Minimum

Species

Calls

Individuals

White-throated Sparrow

17

17

Golden-crowned Kinglet

16

6

Yellow-rumped Warbler

6

5

Dark-eyed Junco

5

2

Song Sparrow

5

5

Boreal Chickadee

4

1

Lincoln's/Swamp Sparrow

4

4

Unidentified Sparrow

3

3

Unidentified Songbird

3

2

Savannah Sparrow

3

3

American Tree Sparrow

2

1

Fox Sparrow

2

2

Blue-headed Vireo

1

1

Hermit Thrush

1

1

Orange-crowned Warbler

1

1

Seaside Sparrow

1

1

Total

74

55


Week of October 19-25


Nocturnal migration over Carleton, Yarmouth County, was down by half compared to the previous two weeks. A total of 125 calls, representing an estimated minimum of 108 birds, was recorded. For the third week in a row, White-throated Sparrow was the most common species with 62 calls. Second was Song Sparrow with 16 calls, followed by Yellow-rumped Warbler (13), Savannah Sparrow (10), and Palm Warbler (7). One Common Yellowthroat was recorded on October 19th. This species has been recorded every week since August 10th. A Clay-colored Sparrow was recorded on October 21st. A summary table follows.


 



Estimated


Total

Minimum

Species

Calls

Individuals

White-throated Sparrow

62

50

Song Sparrow

16

14

Yellow-rumped Warbler

13

12

Savannah Sparrow

10

8

Palm Warbler

7

7

Unidentified Sparrow

6

6

Lincoln's/Swamp Sparrow

2

2

Unidentified Warbler

2

2

Unidentified Songbird

2

2

Blackpoll Warbler

1

1

Clay-colored Sparrow

1

1

Chipping Sparrow

1

1

Common Yellowthroat

1

1

Golden-crowned Kinglet

1

1

Total

125

108


Week of October 12-18


The volume of nocturnal migration over Carleton, Yarmouth County, was about the same this week as the previous week. A total of 221 night flight calls representing an estimated minimum number of 181 individual birds was recorded. Similarly, the proportions of bird families mirrored last week’s with sparrows accounting for 50% of calls, warblers 43%, chickadees 4%, and thrushes less than 1%. The most common bird was White-throated Sparrow with 53 calls, followed by Yellow-rumped Warbler (47), and Savannah Sparrow (19). Common Yellowthroats keep coming. Nine calls of this species representing at least 7 individuals were recorded. Other late warblers included Magnolia (1 individual), Nashville (2), Ovenbird (2), and Black-throated Blue (1). Other seasonably appropriate warblers included Blackpoll (6 individuals), Palm (3), and Orange-crowned (2). One night flight call closely resembled the characteristics of a Hooded Warbler. Unidentified Melospiza flight calls, probably Swamp Sparrows, continued with a total of 13 calls. Other sparrows included  Song Sparrow (9), Chipping Sparrow (1), and Clay-colored Sparrow (1). There was a single Hermit Thrush recorded. This report is followed by a summary table.




Estimated


Total

Minimum

Species

Calls

Individuals

White-throated Sparrow

53

44

Yellow-rumped Warbler

47

35

Savannah Sparrow

19

19

Unidentified Sparrow

14

14

Lincoln's/Swamp Sparrow

13

8

Unidentified Warbler

11

11

Common Yellowthroat

9

7

Song Sparrow

9

6

Black-capped Chickadee

8

5

Unidentified Songbird

8

7

Blackpoll Warbler

6

6

Palm Warbler

5

3

Magnolia Warbler

4

1

Unidentified Warbler Genus Setophaga

4

4

Nashville Warbler

2

2

Orange-crowned Warbler

2

2

Ovenbird

2

2

Black-throated Blue Warbler

1

1

Chipping Sparrow

1

1

Clay-colored Sparrow

1

1

Hermit Thrush

1

1

Hooded Warbler

1

1

Total

221

181



Week of October 5-11


Nocturnal migration over Carleton, Yarmouth County, appeared to be winding down this week. A total night flight call count of 234, representing an estimated minimum number of 176 birds, was the lowest so far for the autumn. For the first time, sparrows outnumbered warblers with 50% of total calls compared to 43% for warblers. Nonetheless, at 189 total calls for the first 11 days of the month, sparrow calls this October are much less than expected. Similarly, a total of only 4 Hermit Thrush calls so far in October is surprisingly low. These low numbers may be more indicative of the location of the monitoring station relative to migratory pathways of different species or species groups and height of the station above sea level. On the other hand, Common Yellowthroats continued their unusual strong showing late into the season with another 16 calls recorded this week. The most common bird this week was White-throated Sparrow (48 calls), followed by Blackpoll Warbler (32) and Yellow-rumped Warbler (21). Black-capped Chickadees first showed signs of nocturnal migration this week with the recording of 7 calls from this species. Unusual or rare birds for this week included Indigo Bunting, Prairie Warbler, Pine Warbler, and a possible Yellow-throated Warbler. A summary table is presented below. I have also provided a graphic on the identification of Northern Parula, Pine Warbler, and Yellow-throated Warbler; all of which have very similar night flight calls. The graphic uses calls that were recorded this week at Carleton and can be found here: Parula NFC Complex.

 



Estimated


Total

Minimum

Species

Calls

Individuals

White-throated Sparrow

48

34

Blackpoll Warbler

32

22

Yellow-rumped Warbler

21

19

Common Yellowthroat

16

12

Dark-eyed Junco

16

1

Lincoln's/Swamp Sparrow

14

12

Palm Warbler

14

12

Unidentified Sparrow

12

10

Song Sparrow

10

10

Savannah Sparrow

9

8

Chipping Sparrow

7

4

Black-capped Chickadee

7

6

Hermit Thrush

4

2

Northern Parula

4

4

Unidentified Warbler

4

4

Unidentified Songbird

4

4

Magnolia Warbler

2

2

Unidentified Warbler Genus Setophaga

2

2

Blackburnian Warbler

1

1

Indigo Bunting

1

1

Ovenbird

1

1

Pine Warbler

1

1

Prairie Warbler

1

1

Swainson's Thrush

1

1

Fox Sparrow

1

1

Yellow-throated Warbler

1

1

Total

234

176



Week of September 28-October 4



The heavy rains during much of the past week greatly suppressed the volume of nocturnal migration over Carleton, Yarmouth County. When the skies cleared during the last two nights of the week, there was a definite push of migrants but they were primarily late warblers with relatively few sparrows. Sparrows still only accounted for 27% of night flight calls this week, up from 24% last week. Overall, it was the slowest migration week this year with a total of only 327 calls representing an estimated minimum number of 267 individuals. The most numerous calls were those of the Common Yellowthroat with 52 calls. Yellow-rumped Warbler was the second most common bird (46 calls), followed by Blackpoll Warbler (38 calls). The most common sparrow call was that of the Lincoln’s/Swamp Sparrow complex (30 calls). Most likely all or largely Swamp Sparrows, it is unusual for this species to outnumber White-throated and Savannah Sparrows. The less common or rare birds of the week included a Pine Warbler and an Indigo Bunting. A summary is included below.

 



Estimated


Total

Minimum

Species

Calls

Individuals

Common Yellowthroat

52

43

Yellow-rumped Warbler

46

40

Blackpoll Warbler

38

33

Lincoln's/Swamp Sparrow

30

15

White-throated Sparrow

29

21

Unidentified Sparrow

19

15

Palm Warbler

19

18

Ovenbird

15

14

Magnolia Warbler

11

8

Northern Parula

11

9

Unidentified Warbler

11

10

Black-throated Green Warbler

6

5

Savannah Sparrow

6

6

Unidentified Warbler Genus Setophaga

6

6

Unidentified Songbird

5

5

Swainson's Thrush

5

3

Black-throated Blue Warbler

4

3

Song Sparrow

4

4

Black-and-White Warbler

2

2

Nashville Warbler

2

1

American Redstart

1

1

Chestnut-sided Warbler

1

1

Hermit Thrush

1

1

Indigo Bunting

1

1

Pine Warbler

1

1

Wilson's Warbler

1

1

Total

327

267

 

Estimation methods for minimum individuals

Warblers and Sparrows: Number of calls of the same taxon that have an interval of at least 60 seconds between them.

Thrushes: The number of calls of the same species during a 60 second period divided by 3 and rounded up to the nearest whole number.




Week of September 21-27


Nocturnal migration was light but steady throughout this past week over Carleton, Yarmouth County. A total of 817 calls, representing at least 669 birds, was recorded. Compared to last week, warblers declined from 86% of calls to 68% while sparrows increased from 8% to 24%. Thrushes remained the same at 4% of calls. The most common bird of the week was Common Yellowthroat at 117 calls, followed by White-throated Sparrow (72), and Yellow-rumped Warbler (63). The count of this late warbler was nearly triple what it was last week. Palm Warblers continued in good numbers (55) while there was a noticeable decline in the once dominant Magnolia Warbler from 329 calls last week to 55 calls this week. The unidentifiable to species Melospizaflight call also increased three-fold this week (38 calls). These likely represent mostly Swamp Sparrows at this time in September. The rare bird for the week was a Brown Thrasher at 6:41 am on 22 September. Uncommon warblers included a Pine Warbler at 5:41 am on 28 September. A summary table follows.

 



Estimated


Total

Minimum

Species

Calls

Individuals

Common Yellowthroat

117

98

White-throated Sparrow

72

58

Yellow-rumped Warbler

63

40

Magnolia Warbler

55

46

Palm Warbler

55

46

Northern Parula

47

35

Savannah Sparrow

44

40

Lincoln's/Swamp Sparrow

38

30

Unidentified Warbler

38

38

Black-and-White Warbler

37

32

Unidentified Sparrow

34

29

Swainson's Thrush

34

20

Black-throated Green Warbler

25

25

Ovenbird

25

22

Blackpoll Warbler

19

17

Unidentified Songbird

17

17

Black-throated Blue Warbler

16

12

Unidentified Warbler Genus Setophaga

16

16

Chestnut-sided Warbler

13

9

American Redstart

10

7

Nashville Warbler

10

7

Chipping Sparrow

6

5

Bay-breasted Warbler

5

4

Blackburnian Warbler

3

2

Dark-eyed Junco

3

2

Pine Warbler

2

2

Prairie Warbler

2

1

Solitary Sandpiper

2

1

Song Sparrow

2

1

Bobolink

1

1

Brown Thrasher

1

1

Cape May Warbler

1

1

Hermit Thrush

1

1

Mourning Warbler

1

1

Rose-breasted Grosbeak

1

1

Wilson's Warbler

1

1

Total

817

669


Week of September 14-20


Nocturnal migration over Carleton, Yarmouth Co., was the heaviest so far this year. The total call count was 1,698 which represents an estimated minimum number of 1,296 individual birds. Warblers still dominated the night skies with 86% of all calls. Sparrows at 8% surpassed thrushes (4%) for the first time. The peak night of the week and of the fall season was the night of September 16-17 when 524 night flight calls were recorded. Despite this peak, the steady passage of Magnolia Warblers (329), Common Yellowthroats (212), and Blackpoll Warblers (135) throughout the week was impressive. The most common sparrow was Savannah at 51 calls, and the most common thrush was Swainson’s at 57 calls. This week saw a strong increase in the number of Palm Warblers (from half a dozen per week to 46 calls). The only rare bird this week was Wood Thrush, the second one this year. A summary for the week is provided below.




Estimated

Total Minimum
Species Calls Individuals
Magnolia Warbler 329 209
Common Yellowthroat 212 156
Blackpoll Warbler 135 102
Unidentified Warbler Genus Setophaga 115 91
Unidentified Warbler   112 101
Northern Parula 110 74
Ovenbird 77 49
Black-and-White Warbler 66 52
Black-throated Green Warbler 57 50
Swainson's Thrush 57 34
American Redstart 52 41
Savannah Sparrow 51 38
Palm Warbler 46 38
Black-throated Blue Warbler 40 28
White-throated Sparrow 40 34
Chestnut-sided Warbler 29 25
Unidentified Sparrow 26 25
Unidentified Songbird 25 47
Yellow-rumped Warbler 22 19
Nashville Warbler 20 15
Bay-breasted Warbler 13 9
Cape May Warbler 13 10
Lincoln's/Swamp Sparrow 12 11
Blackburnian Warbler 7 6
Spotted Sandpiper 6 2
Northern Waterthrush 5 15
Chipping Sparrow 4 3
Hermit Thrush 4 2
Wilson's Warbler 4 3
Greater Yellowlegs 3 1
Canada Warbler 2 2
Mourning Warbler 1 1
Rose-breasted Grosbeak 1 1
Song Sparrow 1 1
Wood Thrush 1 1
Total 1,698 1,296


Week of September 7-13


Nocturnal migration over Carleton, Yarmouth County was considerably dampened by the amount and frequency of rain occurring during the last four days of the week. A total of 674 calls representing an estimated 532 minimum number of individual birds was recorded. However, 51% of these calls occurred on the night of September 12-13. This night started with a northeasterly tailwind for southwest bound migrants. The wind gradually veered to the southeast during the early morning hours. The most common bird of the week was Magnolia Warbler with 120 calls. The second most common bird was Swainson’s Thrush with 100 calls. Common Yellowthroat (68 calls), Northern Parula (38), Black-and-White Warbler (35), and Blackpoll Warbler (32) were the most common warblers after Magnolia Warbler. American Redstarts declined to only 26 calls for the week. Black-throated Blue Warblers continued to impress and Cape May Warblers were down somewhat from the previous week. Uncommon or rare birds for the week included Solitary Sandpiper (1 individual), Scarlet Tanager (2 individuals), White-crowned Sparrow (2 individuals), and Prairie Warbler (3 individuals). A possible Louisiana Waterthrush was recorded at 4:02 am on September 8th. The night flight call can be heard and its spectrogram viewed at https://www.youtube.com/watch?v=5FJnGnxeYCw. The spectrographic characteristics of this call (described at the previous link) were consistent with Louisiana Waterthrush. However, there remains a possibility that this species could be mistaken for an unusually modulated and longer than normal Blackpoll Warbler call. Thus I have included it in the category of unidentified warbler calls. As always, a summary table is provided below.

 



Estimated


Total

Minimum

Species

Calls

Individuals

Magnolia Warbler

120

99

Swainson's Thrush

100

60

Common Yellowthroat

68

52

Northern Parula

38

29

Black-and-White Warbler

35

29

Unidentified Warbler 

34

31

Blackpoll Warbler

32

27

American Redstart

26

21

Black-throated Green Warbler

22

17

Ovenbird

21

19

Black-throated Blue Warbler

19

17

Chestnut-sided Warbler

19

15

Unidentified Warbler Genus Setophaga

17

16

Cape May Warbler

16

16

White-throated Sparrow

13

12

Savannah Sparrow

12

10

Solitary Sandpiper

11

1

Blackburnian Warbler

7

6

Northern Waterthrush

7

5

Unidentified Sparrow

6

6

Bay-breasted Warbler

5

4

Nashville Warbler

5

4

Unidentified Songbird

5

5

Palm Warbler

5

4

Lincoln's/Swamp Sparrow

4

3

Unidentified Warbler Genus Oreothlypis

4

3

Prairie Warbler

4

3

Yellow Warbler

4

4

Rose-breasted Grosbeak

3

3

Scarlet Tanager

2

2

Veery

2

1

White-crowned Sparrow

2

2

Yellow-rumped Warbler

2

2

Bobolink

1

1

Canada Warbler

1

1

Semipalmated Plover

1

1

Unidentified bird

1

1

Total

674

532


Week of August 31-September 6


Nocturnal migration was strong during the first week of September. A total of 1,435 night flight calls comprising a minimum estimated number of 1,079 birds were recorded during the seven day period. The peak night of the week and for the year so far was the night of September 1 to the morning of September 2 when 470 flight calls were recorded. Family composition of the flight calls during the week was 77% warblers of 23 species, 19% thrushes of 3 species, and 2% sparrows of 4 species. American Redstart (180 calls) lost its status this week as the most common species to Swainson’s Thrush (255 calls). However these two species were about tied in estimated minimum number of individuals. The often spectacular pre-dawn descent of thrushes between 5:30 and 6:30 am, when dozens of thrushes can be heard, was strong on the morning of September 2nd and 5th. Common Yellowthroats greatly increased this week, rivalling American Redstart for most common warbler. There was close to a doubling in the number of Northern Parulas and Black-throated Green Warblers. Black-throated Blue and Cape May Warblers made a good showing. As to be expected for the first week of September, Blackpolls began to increase. The consistently low numbers of Wilson’s Warblers and Tennessee Warblers so far this year are worrisome. The highlight of the week was an Indigo Bunting at 10:57 pm on September 4th. A summary table for the week is presented below.





Estimated


Total

Minimum

Species

Calls

Individuals

Swainson's Thrush

255

127

American Redstart

180

137

Common Yellowthroat

142

113

Magnolia Warbler

115

83

Black-and-White Warbler

106

77

Northern Parula

101

82

Ovenbird

88

74

Unidentified Warbler

77

68

Black-throated Green Warbler

70

59

Chestnut-sided Warbler

42

35

Unidentified Warbler Genus Setophaga

36

31

Black-throated Blue Warbler

25

21

Cape May Warbler

22

19

Blackpoll Warbler

20

20

Northern Waterthrush

17

16

Unidentified Songbird

17

12

Savannah Sparrow

12

12

Yellow-rumped Warbler

12

11

Blackburnian Warbler

8

5

Lincoln's/Swamp Sparrow

8

8

Nashville Warbler

8

8

Veery

8

6

White-throated Sparrow

8

8

Palm Warbler

7

6

Canada Warbler

6

5

Mourning Warbler

6

6

Yellow Warbler

6

6

Prairie Warbler

5

4

Unidentified Sparrow

4

4

Golden-crowned Kinglet

4

1

Hermit Thrush

4

2

Unidentified Warbler Genus Oreothlypis

4

3

Wilson's Warbler

4

4

Bay-breasted Warbler

3

2

Chipping Sparrow

2

1

Bobolink

1

1

Indigo Bunting

1

1

Tennessee Warbler

1

1

Grand Total

1,435

1,079


Estimation methods for minimum individuals

Warblers and Sparrows: Number of calls of the same taxon that have an interval of at least 60 seconds between them.

Thrushes: The number of calls of the same species during a 60 second period divided by 3 and rounded up to the nearest whole number.


Week of August 24-30


The migration of warblers continued at the same pace this week at Carleton, Yarmouth County. Total night flight calls numbered 862 with 93% coming from warblers of 21 different species. The most common warbler was again American Redstart, accounting for 239 or 28% of all calls. The next most common were Magnolia Warbler (83 calls), Ovenbird (76), and Black-and-White Warbler (71). Black-throated Blue Warblers continued putting in a good showing with 22 calls and a minimum estimated number of 14 individual birds. Canada Warbler appears to be a very early migrant. Over the past three weeks, their calls have decreased from 37 to 7 to 2. It will be interesting to see if they have a second peak in September. The number of thrushes increased modestly this week with 51 Swainson's Thrush calls, 1 Veery, and 1 Wood Thrush. The rarest bird of the week was an Upland Sandpiper on August 24that 11:14 pm. This is the second time this year that I have recorded this rare shorebird in Nova Scotia. The first being last spring near Amherst. This leads me to wonder if the Upland Sandpiper might be somewhat more frequent in the province than what is seen by birders. This is true for other species such as Indigo Bunting and Gray-cheeked Thrush. Nocturnal flight call recordings of these species indicate that they occur more often than what is reported by the birding community. A summary of the week’s recordings is presented below.





Estimated


Total

Minimum

Species

Calls

Individuals

American Redstart

239

144

Magnolia Warbler

83

55

Ovenbird

76

68

Black-and-White Warbler

71

52

Unidentified Warbler

70

63

Northern Parula

54

38

Swainson's Thrush

51

27

Black-throated Green Warbler

37

23

Common Yellowthroat

37

32

Chestnut-sided Warbler

26

21

Unidentified Setophaga Warbler

25

22

Black-throated Blue Warbler

22

14

Northern Waterthrush

17

11

Bay-breasted Warbler

8

6

Cape May Warbler

8

8

Nashville Warbler

5

4

Yellow Warbler

5

4

Blackburnian Warbler

4

3

Blackpoll Warbler

4

4

Palm Warbler

3

2

Savannah Sparrow

3

3

Canada Warbler

2

2

Unidentified Songbird

2

2

Upland Sandpiper

2

1

Wilson's Warbler

2

2

Lincoln's/Swamp Sparrow

1

1

Prairie Warbler

1

1

Veery

1

1

Wood Thrush

1

1

White-throated Sparrow

1

1

Yellow-rumped Warbler

1

1

Total

862

617



Week of August 17-23


Nocturnal migration at Carleton, Yarmouth County, was steady and slightly down from last week with a call count of 759, down from 890. Warblers accounted for 96% of the calls while the remaining 4% were thrush calls (Swainson’s Thrushes and one Veery). A total of 20 species of warblers were recorded. American Redstarts again overwhelmed the counts with 221 calls and an estimated minimum number of 132 individual birds. Ovenbird overtook Magnolia Warbler in second place with 98 and 57 calls respectively. Black-and-White and Chestnut-sided Warblers continued in good numbers. Yellow Warblers already showed signs of declining numbers while Common Yellowthroats began to increase. Cape May Warblers put in a better showing this week while Black-throated Blue Warblers continued stronger than in previous years. Less common or rare warblers included one Prairie Warbler and a possible Prothonotary Warbler. For those who are interested, the possible Prothonotary Warbler can be heard and its spectrogram viewed at: https://www.youtube.com/watch?v=46DDNqFv72c.  A table summarizing this week’s nocturnal migration follows.





Estimated


Total

Minimum

Species

Calls

Individuals

American Redstart

221

132

Ovenbird

98

69

Magnolia Warbler

69

52

Unidentified Warbler

57

53

Black-and-White Warbler

50

35

Chestnut-sided Warbler

43

33

Unidentified Warbler Genus Setophaga

37

34

Common Yellowthroat

32

23

Northern Parula

32

21

Swainson's Thrush

26

14

Cape May Warbler

19

9

Yellow Warbler

18

13

Black-throated Blue Warbler

12

8

Northern Waterthrush

12

9

Canada Warbler

7

7

Blackpoll Warbler

5

5

Blackburnian Warbler

4

4

Black-throated Green Warbler

4

4

Unidentified Warbler Genus Oreothlypis

4

2

Bay-breasted Warbler

3

3

Nashville Warbler

1

1

Prothonotary Warbler

1

1

Prairie Warbler

1

1

Savannah Sparrow

1

1

Tennessee Warbler

1

1

Veery

1

1

Total

759

536



Week of August 10-16


Songbird migration is underway. This week I setup recording equipment at my home in Carleton, Yarmouth County. Since I’m setting the equipment up near a power source and don’t have to use a battery-powered recording unit, I can use a more powerful microphone. It captures somewhere between 1.5 to 5 times more calls than my field microphones, depending on the species. This microphone has a maximum reach of about 300 meters. Thus the numbers will be higher compared to what I have reported from my field microphones but there will be also more unidentified calls. The latter results from the mic picking up distant calls that are too weak to determine the bird species but clear enough to identify the family or genus of the bird.

So in total I recorded 890 calls this week, with 98% being warbler calls. I’m still trying to provide you with more accurate estimates as to how many birds these calls represent. I’ve adopted a new estimation technique, one employed by an acoustic monitoring network in the United States, organized by Bill Evans. In this method, any call that is recorded within 1 minute of another call is considered as coming from the same bird. Calls 1 minute apart or more are considered as coming from separate birds. This, I believe, gives a good minimum estimate of the number of individuals represented by a given number of calls. However, I must emphasize that it is a minimum estimation since it is believed that birds may use night flight calls as a way to communicate, and thus two calls a second or two apart could be two different birds calling to each other.

The table below lists the call count and the estimate of the minimum number of birds of each species or species group. American Redstarts dominate the early migration. The other most common early migrating warblers are Magnolia, Black-and-White, Black-throated Green, Yellow, Chestnut-sided, Canada, Ovenbird, and Northern Parula. I suspect the Canada Warbler numbers were higher since I noted a number of weak calls from higher flying birds that suggested this species. Numbers of Northern Waterthrush and Cape May Warbler are disappointing and while numbers of Black-throated Blue Warblers are encouraging compared to past years. Less common or rare species recorded were Prairie Warbler, Pine Warbler, and Blue-winged Warbler. Given the difficulties of warbler night flight call id, these identifications must be viewed as “possible” rather than confirmed. The call of the most uncommon of these, the Blue-winged Warbler is posted for anyone who is interested at: https://www.youtube.com/watch?v=nNLbDv66D5U. It is similar to the call of the Ovenbird but the relatively long length of this call is more typical of Blue-winged Warbler than Ovenbird.



Minimum

Species

Calls

Individuals

American Redstart

207

131

Unidentified Warblers

87

71

Magnolia Warbler

82

59

Unidentified Setophaga Warblers

69

57

Black-and-White Warbler

68

50

Black-throated Green Warbler

58

29

Yellow Warbler

52

41

Chestnut-sided Warbler

49

35

Ovenbird

38

28

Canada Warbler

37

32

Northern Parula

32

21

Northern Waterthrush

17

14

Bay-breasted Warbler

15

14

Blackburnian Warbler

15

14

Black-throated Blue Warbler

15

10

Swainson's Thrush

9

6

Cape May Warbler

7

6

Common Yellowthroat

7

7

Prairie Warbler

5

4

Yellow-rumped Warbler

5

3

Nashville Warbler

4

2

Lincoln's/Swamp Sparrow

3

2

Pine Warbler

2

1

Wilson's Warbler

2

2

Blackpoll Warbler

1

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