Environmental and Social Research

John F. Kearney & Associates

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%







Nocturnal Acoustic Monitoring of Migratory Birds 2016


Carleton Station, Yarmouth County, Nova Scotia (N43.9967, W65.9159)





Weekly Reports for the Autumn 2016

 

2ndWeek of November

 

This will be the last report on nocturnal migration at Carleton, Yarmouth County, for the autumn of 2016.

There was a total of 36 night flight calls this week, representing an estimated 18 individual birds. The most common birds were Dark-eyed Junco (27 calls) and Savannah Sparrow (2). A Grasshopper Sparrow recorded on 8 November was one day later than a bird of the same species on 7 November 2015. A late Common Yellowthroat was recorded on 9 November.

There was very little evidence of nocturnal migration on the weather radar at Caribou, Maine, this week.

A table showing the total calls, peak counts, and peak dates for each species recorded in 2015 and 2016 can be found here. While the total number of calls was quite similar in both years, there were some major differences at the species level.

Notable increases could be seen in Black-and-White Warbler, Blackburnian Warbler, Black-throated Green Warbler, Black-throated Blue Warbler, Common Yellowthroat, Cape May Warbler, Swamp/Lincoln’s Sparrow, Northern Waterthrush, Northern Parula, Hermit Thrush, Palm Warbler, Savannah Sparrow, White-crowned Sparrow, Solitary Sandpiper, Song Sparrow, Veery, Wilson’s Warbler, Yellow Warbler, Tennesee Warbler, and Yellow-rumped Warbler.

Declines were seen in American Redstart, Canada Warbler, Chestnut-sided Warbler, Magnolia Warbler, Ovenbird, Swainson’s Thrush, and White-throated Sparrow.

A summary table for this week follows.

Thanks for your interest in these reports during this autumn season of 2016.




Estimated


Total

Minimum

Species

Calls

Individuals*

Dark-eyed Junco

27

9

Savannah Sparrow

2

2

American Tree Sparrow

1

1

Common Yellowthroat

1

1

Unidentified Sparrow

1

1

Fox Sparrow

1

1

Grasshopper Sparrow

1

1

Song Sparrow

1

1

Unidentified Songbird

1

1

Total

36

18

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

1stWeek of November

 

Nocturnal migration was very slow this week at Carleton, Yarmouth County. The weather radar in Caribou, Maine, also showed little evidence of bird migration. At Portland, Maine, it appeared that some larger birds were heading southwest along the coast of Maine as late as the night of 7 November.

The most common birds at Carleton this week were Song Sparrow (8 calls), White-throated Sparrow (7), Dark-eyed Junco (5), and Palm Warbler (5). The last species represents 2 birds that were recorded 2:43 am on 2 November.

There remains the possibility of further nocturnal movements by juncos and sparrows in the coming week. A summary table for this week follows.  




Estimated


Call

Minimum

Species

Count

Individuals*

Song Sparrow

8

5

White-throated Sparrow

7

7

Dark-eyed Junco

5

3

Palm Warbler

5

2

Golden-crowned Kinglet

4

2

Unidentified Sparrow

2

2

Fox Sparrow

2

1

Hermit Thrush

1

1

Lincoln's/Swamp Sparrow

1

1

Savannah Sparrow

1

1

Total

36

25

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

4thWeek of October

 

Nocturnal migration declined further this week at Carleton, Yarmouth County. Total calls fell to 49 with an estimated minimum of 29 individual birds. The most common calls were Dark-eyed Junco (28 calls), Fox Sparrow (6), and White-throated Sparrow (5). The first American Tree Sparrow was heard at 8 minutes past midnight on 28 October.

Sparrows accounted for 86% of all calls and warblers for 12%. The two warbler species recorded were Blackpoll Warbler and Yellow-rumped Warbler.

The weather radar at Caribou, Maine, displayed a corresponding paucity of migrants. The number of echoes was somewhat higher in Portland, Maine, while there still seemed to be nights of good migration in the mid-Atlantic states.

A summary table is found below.




Estimated


Total

Minimum

Species

Calls

Individuals*

Dark-eyed Junco

28

11

Fox Sparrow

6

5

White-throated Sparrow

5

5

Blackpoll Warbler

3

3

Killdeer

3

1

Unidentified Sparrow

2

2

American Tree Sparrow

1

1

Yellow-rumped Warbler

1

1

Total

49

29

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

3rdWeek of October

 

Nocturnal migration was down to 88 flight calls at Carleton, Yarmouth County, this week. The minimum number of individual migrants was 78. The most common species was White-throated Sparrow (23 calls) and Yellow-rumped Warbler (11). Sparrows accounted for 63% of all calls, warblers for 25%, and Kinglets for 7%. Straggling warblers included a Black-throated Green Warbler and a Black-throated Blue Warbler.

The weather radar in Caribou, Maine, indicated a similar low volume of migratory activity based on the density of echoes in clear-air mode.

A summary table is given below.



Estimated


Call

Minimum

Species

Count

Individuals*

White-throated Sparrow

23

14

Unidentified Sparrow

11

11

Yellow-rumped Warbler

11

11

Savannah Sparrow

9

8

Song Sparrow

7

11

Golden-crowned Kinglet

6

3

Unidentified Songbird

5

5

Palm Warbler

5

5

Blackpoll Warbler

3

3

Lincoln's/Swamp Sparrow

3

3

Dark-eyed Junco

2

1

Black-throated Blue Warbler

1

1

Black-throated Green Warbler

1

1

Unidentified Warbler

1

1

Total

88

78

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

2ndWeek of October

 

Nocturnal migration is winding down over Carleton, Yarmouth County. Total flight calls were down to 203 this week with an estimated minimum of 177 individual nocturnal migrants. The remnants of Hurricane Matthew, with heavy rain and high wind, brought migration to an apparent standstill for two days.

The most common bird of the week was Yellow-rumped Warbler (34 calls), followed by Savannah Sparrow (33 including 1 Ipswich Sparrow), Palm Warbler (29), and White-throated Sparrow (23).

The weather radar at Caribou, Maine, this week continued to show echoes travelling west and northwest over the Bay of Fundy.

A summary table for the week is below.



Estimated


Total

Minimum

Species

Calls

Individuals*

Yellow-rumped Warbler

34

32

Savannah Sparrow

33

27

Palm Warbler

29

22

White-throated Sparrow

23

22

Song Sparrow

16

13

Lincoln's/Swamp Sparrow

11

8

Unidentified Songbird

11

10

Common Yellowthroat

9

9

Blackpoll Warbler

6

6

Black-throated Blue Warbler

5

3

Black-throated Green Warbler

4

4

Northern Parula

4

4

Black-capped Chickadee

3

2

Dark-eyed Junco

2

2

Hermit Thrush

2

2

Magnolia Warbler

2

2

Unidentified Warbler

2

2

American Robin

1

1

Chipping Sparrow

1

1

Unidentified Sparrow

1

1

Fox Sparrow

1

1

Nelson's Sparrow

1

1

Unidentified Warbler Genus Oreothlypis

1

1

Wilson's Warbler

1

1

Total

203

177

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

 

1stWeek of October

 

Nocturnal migration over Carleton, Yarmouth County, this week was only one-fifth the intensity of the previous period. A total of 451 flight calls were recorded at a rate of 64 per night. The estimated minimum number of individuals was 377. The most abundant species were White-throated Sparrow with 53 calls and Yellow-rumped Warbler with 52. The other most common species this week were Common Yellowthroat (43 calls), Lincoln’s/Swamp Sparrow (39), Song Sparrow (37), Palm Warbler (34), Savannah Sparrow (27), Blackpoll Warbler (22), and Northern Parula (21). Warblers accounted for 53% of the species recorded, sparrows for 41%, and other bird families for 6%.

Unusual or new birds for the week included: Orange-crowned Warbler, Field Sparrow, Vesper Sparrow, and White-crowned Sparrow. Late Chestnut-sided Warblers were recorded on the evening of 6 October.

The Caribou, Maine, radar showed a corresponding decrease in bird echoes during this week. There was also an interesting shift of flight direction on some nights to the west and northwest. This is very consistent with results obtained by smaller-scale marine radars used by ornithologists who have noted these more westerly movements over the Bay of Fundy in later part of fall migration. It is believed that these birds cross the Bay of Fundy to avoid a more perilous route over the Gulf of Maine.

A summary of the week can be found below.




Estimated


Total

Minimum

Species

Calls

Individuals*

White-throated Sparrow

53

43

Yellow-rumped Warbler

52

43

Common Yellowthroat

43

34

Lincoln's/Swamp Sparrow

39

32

Song Sparrow

37

28

Palm Warbler

34

29

Savannah Sparrow

27

22

Blackpoll Warbler

22

22

Unidentified Sparrow

21

19

Northern Parula

20

16

Magnolia Warbler

16

13

Unidentified Warbler Genus Setophaga

12

12

Black-capped Chickadee

10

10

Unidentified Songbird

10

10

Black-throated Blue Warbler

9

6

Unidentified Warbler

9

9

Black-throated Green Warbler

8

7

Golden-crowned Kinglet

5

2

Chestnut-sided Warbler

4

2

Hermit Thrush

4

3

Orange-crowned Warbler

3

2

Dark-eyed Junco

2

2

Ovenbird

2

2

Black-and-White Warbler

1

1

Blackburnian Warbler

1

1

Chipping Sparrow

1

1

Field Sparrow

1

1

Nashville Warbler

1

1

Unidentified Warbler Genus Oreothlypis

1

1

Vesper Sparrow

1

1

White-crowned Sparrow

1

1

Wilson's Warbler

1

1

Total

451

377

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

4thWeek of September

 

It was a week of spectacular nocturnal migration at Carleton, Yarmouth County. With a total of 2,215 night flight calls, and a estimated minimum of 1,859 birds, this nine-day period accounted for 29% of all the flight calls that have been detected since the last week of July. The average nightly rate was 246 calls, about 50 calls per night higher than during the first week of September.

There were two major flights during this period; the night of 22-23 September when 742 calls were detected and the night of 29-30 September when 648 calls were recorded. The first of these nights, the 22nd-23rd, appeared to be a fallout of birds resulting from rain coming across the Bay of Fundy during the night. You can find more details about these conditions here. The flight on the second night, the 29-30th, seems to be the result of moderately strong northeast winds through the entire night. Just after dusk the winds were from the northeast at 35 km/hr and had diminished to 24 km/hr at dawn. This provided a tail wind for southwest movement. The steady flow of calls through the night indicated that birds were both departing and arriving.

Among species groups, 65% of the calls this week were warblers, 28% sparrows, and 2% thrushes. The most common warblers were Common Yellowthroat (380 calls), Yellow-rumped Warbler (147), Palm Warbler (130), Magnolia Warbler (121), and Northern Parula (108). The most common sparrows were Savannah Sparrow (163), White-throated Sparrow (159), and Lincoln’s/Swamp Sparrow (155). Given the time of the season, the last group would be largely or entirely Swamp Sparrows. The most common thrush was Swainson’s Thrush (39).

Among the unusual birds of the week were 11 White-crowned Sparrows during the flight of the 29-30th. There were probably even several more as I noted some weaker calls that were likely this species. Also recorded during the week were 6 Indigo Buntings, 1 Prairie Warbler, 1 late Canada Warbler on 24 September, and a possible Prothonotary Warbler on 23 September (weak call). Among the 77 Savannah Sparrow calls on the 29-30th were two Ipswich Sparrows. A summary table can be found below.




Estimated


Total

Minimum

Species

Calls

Individuals*

Common Yellowthroat

380

282

Savannah Sparrow

163

130

White-throated Sparrow

159

120

Lincoln's/Swamp Sparrow

155

114

Yellow-rumped Warbler

147

119

Palm Warbler

130

105

Magnolia Warbler

121

96

Northern Parula

108

88

Unidentified Sparrow

100

88

Black-and-White Warbler

95

77

Unidentified Warbler

87

83

Black-throated Green Warbler

83

71

Blackpoll Warbler

80

73

Unidentified Songbird

60

145

Unidentified Warbler Genus Setophaga

42

41

Swainson's Thrush

39

24

Black-throated Blue Warbler

34

29

Solitary Sandpiper

28

4

Ovenbird

27

23

Song Sparrow

26

19

American Redstart

21

16

Blackburnian Warbler

17

15

Cape May Warbler

17

11

Chestnut-sided Warbler

14

14

Golden-crowned Kinglet

13

6

White-crowned Sparrow

11

11

Chipping Sparrow

7

7

Bay-breasted Warbler

6

6

Hermit Thrush

6

4

Indigo Bunting

6

6

Wilson's Warbler

6

6

Nashville Warbler

5

4

Mourning Warbler

4

4

Nelson's Sparrow

4

4

Dark-eyed Junco

3

3

Unidentified Warbler Genus Oreothlypis

3

3

Yellow Warbler

2

2

American Pipit

1

1

Canada Warbler

1

1

Gray-cheeked Thrush

1

1

Northern Waterthrush

1

1

Prothonotary Warbler (possible)

1

1

Prairie Warbler

1

1

Total

2,215

1,859

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

3rdWeek of September

 

Total night flight calls at Carleton, Yarmouth County, were down from the previous week due to rainy and unsettled weather during the period of 17-20 September. There was a total of 828 calls, at a nightly rate of 118. Species consisted 79% of warblers, 11% of thrushes, 9% of sparrows, and 1% of other family types. The most common species of the week were Common Yellowthroat with 181 calls, Magnolia Warbler (71), Northern Parula (54), Blackpoll Warbler (47), Black-and-white Warbler (44), American Redstart (40), Black-throated Green Warbler (39), and Swainson’s Thrush (36). There was a marked increase in Palm Warblers (22), and the first movement of Hermit Thrushes was on 15 September. Cape May Warblers (2) were scarce while Black-throated Blue Warblers continued at the same pace (21) as previously. A further expected increase in Yellow-rumped Warblers did not yet materialize. Rare birds for the week were Indigo Bunting and Gray-cheeked Thrush. The Gray-cheeked Thrush has quite a distinct flight call which you can hear by clicking on this link: Gray-cheeked Thrush Flight Call. The best time to listen is in the hour or two before dawn. A summary for the week follows in the table below

 



Estimated


Total

Minimum

Species

Calls

Individuals*

Common Yellowthroat

181

136

Magnolia Warbler

71

57

Northern Parula

54

46

Blackpoll Warbler

47

41

Black-and-White Warbler

44

35

American Redstart

40

28

Black-throated Green Warbler

39

34

Unidentified Warbler

39

35

Swainson's Thrush

36

28

Savannah Sparrow

29

22

Yellow-rumped Warbler

27

20

Unidentified Warbler Genus Setophaga

23

22

Chestnut-sided Warbler

22

19

Palm Warbler

22

17

White-throated Sparrow

22

18

Black-throated Blue Warbler

21

20

Hermit Thrush

19

7

Unidentified Sparrow

15

14

Ovenbird

13

12

Nashville Warbler

11

6

Unidentified Songbird

9

8

Bay-breasted Warbler

8

7

Lincoln's/Swamp Sparrow

6

6

Blackburnian Warbler

5

5

Song Sparrow

5

2

Wilson's Warbler

5

4

Cape May Warbler

2

2

Northern Waterthrush

2

2

Solitary Sandpiper

2

1

Tennessee Warbler

2

1

Veery

2

2

Unidentified Thrush

1

1

Canada Warbler

1

1

Gray-cheeked Thrush

1

1

Indigo Bunting

1

1

Mourning Warbler

1

1

Total

828

661

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

2ndWeek of September

 

The highest nocturnal count of the autumn so far at Carleton, Yarmouth County, occurred this week on the night of 9-10 September. This peak, with 542, calls was roughly equivalent in number to the peak for the entire season last year that occurred on the night of 16-17 September. After the 9th of September, the strength of migration was light to moderate, giving a total of 926 calls for the week or a mean of 132 per night. Warblers composed 87% of all calls, thrushes, 7%, and sparrows, 4%. The most common species for the week were Northern Parula (103 calls), Common Yellowthroat (93), Blackpoll Warbler (85), Black-throated Green Warbler (82), Magnolia Warbler (71), and Swainson’s Thrush (61). A good flight of Cape May Warbler (30), and Black-throated Blue Warbler (21) continued this week. Rare birds for the week included 1 Upland Sandpiper, 2 Pine Warblers, 1 Prairie Warbler, and 1 Vesper Sparrow.

There continues to be a good correlation between the density of echoes on the weather radar at Caribou, Maine and the number of flight calls detected acoustically at Carleton, Nova Scotia. This was true on the night of 9-10 September when parts of the sky in Maine had an echo (bird) density of 600 per cubic kilometer. This was the highest I have seen this year. The echoes moved in the direction of south-southeast in the early evening and veered to south-southwest as the night progressed. This seemed to indicate a movement to the coast from northern New Brunswick/Maine and then along the coast of Maine.

A summary for the week can be found in the table that follows.



Estimated


Call

Minimum

Species

Count

Individuals*

Northern Parula

103

74

Common Yellowthroat

93

70

Blackpoll Warbler

85

72

Black-throated Green Warbler

82

45

Magnolia Warbler

71

56

Unidentified Warbler

64

57

Swainson's Thrush

61

42

American Redstart

54

43

Yellow-rumped Warbler

40

30

Black-and-White Warbler

39

32

Unidentified Warbler Genus Setophaga

33

28

Cape May Warbler

30

23

Black-throated Blue Warbler

21

16

Ovenbird

20

17

White-throated Sparrow

18

15

Northern Waterthrush

11

8

Chestnut-sided Warbler

10

9

Bay-breasted Warbler

9

7

Blackburnian Warbler

9

9

Lincoln's/Swamp Sparrow

8

7

Veery

7

4

Unidentified Sparrow

6

5

Unidentified Warbler Genus Oreothlypis

6

6

Palm Warbler

6

6

Nashville Warbler

5

5

Unidentified Songbird

5

5

Canada Warbler

4

2

Pine Warbler

4

2

Chipping Sparrow

3

3

Upland Sandpiper

3

1

Mourning Warbler

2

2

Song Sparrow

2

2

Wilson's Warbler

2

2

Yellow Warbler

2

2

Bobolink

1

1

Unidentified Shorebird

1

1

Hermit Thrush

1

1

Prairie Warbler

1

1

Rose-breasted Grosbeak

1

1

Savannah Sparrow

1

1

Tennessee Warbler

1

1

Vesper Sparrow

1

1

Total

926

715

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

 

1stWeek of September

 

It was a busy week for nocturnal migration at Carleton, Yarmouth County. There was a total of 1,383 calls at a rate of 198 calls per night. There was an estimated minimum of 1,117 birds. Warbler composition fell to 79% of calls due to the influx of Swainson’s Thrushes and Veeries. The most common birds for the week were Common Yellowthroat (190), American Redstart (160), Magnolia Warbler (152), Northern Parula (125), Black-and-White Warbler (116), Swainson’s Thrush (88), and Black-throated Green Warbler (64). There was a more than average flight of Wilson’s Warbler, with 37 flight calls recorded. The peak for the week and for the autumn season thus far was the night of 2-3 September when 469 calls were recorded. Rare birds for the week included 4 Prairie Warblers, 2 Pine Warblers and 1 Indigo Bunting. A sparrow recorded at 10:22 pm on 6 September was a possible Seaside Sparrow. A discussion of this flight call can be found here A summary list follows.




Estimated


Call

Minimum

Species

Count

Individuals*

Common Yellowthroat

190

150

American Redstart

160

124

Magnolia Warbler

152

122

Northern Parula

125

90

Black-and-White Warbler

116

90

Swainson's Thrush

88

58

Black-throated Green Warbler

64

54

Unidentified Warbler

47

43

Wilson's Warbler

37

31

Northern Waterthrush

34

24

Ovenbird

34

29

Chestnut-sided Warbler

32

27

Blackpoll Warbler

31

30

Black-throated Blue Warbler

31

29

Unidentified Warbler Genus Setophaga

30

28

Cape May Warbler

27

22

Yellow-rumped Warbler

27

24

Yellow Warbler

16

15

Unidentified Songbird

14

12

Savannah Sparrow

14

12

White-throated Sparrow

14

10

Unidentified Warbler Genus Oreothlypis

13

12

Palm Warbler

12

12

Veery

11

8

Lincoln's/Swamp Sparrow

10

8

Nashville Warbler

10

6

Blackburnian Warbler

9

7

Bay-breasted Warbler

7

16

Unidentified Sparrow

6

6

Mourning Warbler

6

5

Prairie Warbler

5

4

Solitary Sandpiper

3

1

Canada Warbler

2

2

Pine Warbler

2

2

Indigo Bunting

1

1

Rose-breasted Grosbeak

1

1

Seaside Sparrow

1

1

Tennessee Warbler

1

1

Total

1,383

1,117

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

4thWeek of August

 

Nocturnal migration at Carleton, Yarmouth County, was moderate to strong on about half the nights in this ten-day period. There was a large flight the night of 27-28 August with 300 calls recorded. Overall for the week, there was a total 934 calls at a rate of 93 per night and an estimated minimum of 763 birds. With the beginnings of the Swainson’s Thrush migration this week, the percentage of warbler calls fell to 90% of the total. The most common species were American Redstart (148 calls), Common Yellowthroat (92), Northern Parula (84), Black-and-White Warbler (69), Magnolia Warbler (65), and Swainson’s Thrush (53). There were some good nights for Northern Waterthrush, Black-throated Blue Warbler, and Cape May Warbler. The rare bird for the week was a possible Yellow-throated Warbler. Its call is very similar to Northern Parula but an analysis of its spectrogram better fit the parameters for a Yellow-throated Warbler.

There was a good correlation of the birds recorded at Carleton and the number of (bird) echoes on the weather radar at Caribou, Maine. This was especially true on the night of 27-28 August when the Caribou radar showed a density of 227 (bird) echoes per cubic kilometer. A summary table for the week is below.




Estimated


Total

Minimum

Species

Calls

Individuals*

American Redstart

148

114

Common Yellowthroat

92

78

Northern Parula

84

68

Black-and-White Warbler

69

59

Magnolia Warbler

65

53

Unidentified Warbler

62

59

Swainson's Thrush

53

31

Ovenbird

46

40

Northern Waterthrush

45

31

Black-throated Blue Warbler

31

25

Black-throated Green Warbler

30

28

Unidentified Warbler Genus Setophaga

28

25

Yellow Warbler

27

25

Cape May Warbler

23

20

Chestnut-sided Warbler

20

16

Wilson's Warbler

16

14

Blackburnian Warbler

14

12

Bay-breasted Warbler

10

7

Blackpoll Warbler

8

8

Nashville Warbler

8

6

Yellow-rumped Warbler

7

6

Palm Warbler

6

4

Canada Warbler

5

5

Rose-breasted Grosbeak

4

2

Unidentified Songbird

3

3

Prairie Warbler

3

3

Tennessee Warbler

3

1

White-throated Sparrow

3

3

Yellow-throated Warbler

3

1

Black-capped Chickadee

2

2

Unidentified Sparrow

2

2

Lincoln's/Swamp Sparrow

2

2

Unidentified Warbler Genus Oreothlypis

2

2

Spotted Sandpiper

2

1

Veery

2

1

Bobolink

1

1

Unidentified Thrush

1

1

Hermit Thrush

1

1

Mourning Warbler

1

1

Savannah Sparrow

1

1

Song Sparrow

1

1

Total

934

763

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number



 

 

3rdWeek of August

 

Nocturnal migration at Carleton, Yarmouth County, intensified further this week. A total of 598 calls were recorded. These represent an estimated minimum of 475 individuals and 22 warbler, 2 thrush, 2 sparrow, and 1 sandpiper species. The most abundant species were American Redstart, Ovenbird, Magnolia Warbler, and Black-and-White Warbler, in that order. Peak nights were 19 and 20 August when 177 and 122 calls were recorded respectively.

The intensity of radar echoes at Caribou, Maine, was greatest on the nights of 17-19 August. On these nights, the echo intensity ranged between 15-20 decibels which would represent about 100-225 birds per cubic kilometer. This lag between the intensity of migration at Caribou and Carleton may be the result of weather systems passing through Caribou first.

Graphs recently added to my website show that the number of flight calls at Carleton increases with increasing intensity of echoes on the Caribou radar. Another graph illustrates that most birds flying over Carleton correspond to southwest movements of echoes on the Caribou radar.

This week saw increases over last week in Common Yellowthroat and Northern Waterthrush. The first Blackpoll Warblers of the year appeared this week. A summary of all observations follows below.

It should be noted as well that field observers, including myself, saw large numbers of Red-breasted Nuthatches this week. Although a nocturnal migrant, they are infrequently recorded on acoustic monitoring devices. However, these movements of nuthatches correspond to the dates when warblers were moving in Carleton.



Estimated


Call

Minimum

Species

Count

Individuals*

American Redstart

67

49

Ovenbird

65

50

Magnolia Warbler

53

39

Black-and-White Warbler

52

40

Unidentified Warbler

50

42

Chestnut-sided Warbler

45

30

Northern Parula

43

33

Yellow Warbler

35

30

Common Yellowthroat

33

25

Unidentified Warbler Genus Setophaga

26

24

Northern Waterthrush

24

23

Black-throated Blue Warbler

20

14

Blackburnian Warbler

15

15

Yellow-rumped Warbler

13

12

Black-throated Green Warbler

6

4

Nashville Warbler

6

4

Tennessee Warbler

5

5

Bay-breasted Warbler

4

4

Blackpoll Warbler

4

4

Canada Warbler

4

4

Cape May Warbler

4

4

Unidentified Warbler Genus Oreothlypis

4

4

Prairie Warbler

4

2

Swainson's Thrush

4

3

Unidentified Songbird

3

3

Palm Warbler

2

2

Solitary Sandpiper

2

1

Wilson's Warbler

2

2

Chipping Sparrow

1

1

Song Sparrow

1

1

Veery

1

1

Total

598

475

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

 

2ndWeek of August

It was the week of the Black-and-White Warbler! It is perhaps the largest number of these birds that I’ve had in one week since I started acoustic monitoring. With 86 calls, this warbler outnumbered all others, including the American Redstart which is usually the most abundant warbler at this time in August. There was even a fall-out of Black-and-White Warblers and American Redstarts on the morning of 13 August. In 1 minute and 20 seconds, I recorded 39 Black-and-White Warbler calls and 21 calls of American Redstart.

Overall for the week, I had 414 calls at an average rate of 59 calls per night. The estimated minimum number of individual birds was 283. Warblers composed 97% of all calls. Among the most common warblers were Ovenbird, Magnolia Warbler, Yellow Warbler, Northern Parula, and Black-throated Blue Warbler.

The most unusual bird of the week was a single American Pipit on 9 August at 11:41 pm.

A summary of all calls recorded is provided in the table below.

The radars in Maine were in precipitation mode for much of the week. Thus the weather in Maine may have resulted in some back up of warblers in Southwest Nova Scotia.



Estimated


Call

Minimum

Species

Count

Individuals*

Black-and-White Warbler

86

45

American Redstart

59

38

Ovenbird

36

22

Unidentified Warbler

30

24

Magnolia Warbler

29

21

Yellow Warbler

28

23

Northern Parula

20

12

Black-throated Blue Warbler

19

15

Unidentified Warbler Genus Setophaga

18

18

Chestnut-sided Warbler

14

10

Blackburnian Warbler

11

10

Black-throated Green Warbler

10

7

Common Yellowthroat

9

6

Canada Warbler

7

7

Northern Waterthrush

7

6

Spotted Sandpiper

6

2

Yellow-rumped Warbler

6

4

Unidentified Warbler Genus Oreothlypis

5

2

Nashville Warbler

4

3

Unidentified Songbird

4

3

Palm Warbler

2

1

American Pipit

1

1

Bay-breasted Warbler

1

1

Cape May Warbler

1

1

Savannah Sparrow

1

1

Total

414

283




* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number



 

 

1stWeek of August

 

The rate of nocturnal movements of warblers almost doubled over the previous week. There was a total of 240 calls and at least 181 individual birds at a rate of 34 calls per night. Warblers composed 99% of the calls recorded. Despite a continuing variety in species composition, early migrating warbler species dominated the count. The most common species were American Redstart (69 calls), Black-and-White Warbler (45 calls), and Yellow Warbler (34 calls). The numbers of these three species seemed to indicate true, south-bound migration, rather than post-breeding dispersion. A summary list can be found below.

The weather radars in the state of Maine, at Caribou and Portland, showed only light activity but with evidence of bird migration on most nights when there was no rain.

 



Estimated


Call

Minimum

Species

Count

Individuals*

American Redstart

69

45

Black-and-White Warbler

45

32

Yellow Warbler

34

28

Unidentified Warbler

18

15

Chestnut-sided Warbler

13

10

Magnolia Warbler

10

9

Northern Parula

10

7

Blackburnian Warbler

9

8

Black-throated Blue Warbler

9

7

Unidentified Warbler Genus Setophaga

7

6

Tennessee Warbler

6

4

Canada Warbler

3

3

White-throated Sparrow

3

3

Bay-breasted Warbler

1

1

Black-throated Green Warbler

1

1

Cape May Warbler

1

1

Northern Waterthrush

1

1

Total

240

181

 

* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number

 

 

4thWeek of July

 

Nocturnal movements of birds over Carleton, Yarmouth County, ranged from 1 to 33 calls per night with an average of 18. The total was 183. Warblers predominated with the early migrating American Redstart being the most common. But the second most common warbler was Northern Parula, a warbler that tends to peak in September. This would indicate that the birds were a mix of birds in post-breeding dispersion and early migrants. The half-dozen sparrows (mainly White-throats) were likely moving between habitats rather than migrating. One Swainson’s Thrush giving a flight call about an hour after sunset on 26 July might have been a local bird leaving or expressing migratory restlessness. The inland sandpipers, Spotted and Solitary, were heard regularly during the period. All species recorded are listed in the summary table below.

The highest number of calls was recorded on the night of 31 July to 1 August. On that night, the Portland, Maine, radar was operating in precipitation mode but the Caribou, Maine, radar was in clear air mode. The density of echoes over Caribou was light through most of the night (about 60 per cubic km). The direction of movement was west-southwest. The dominant speed was 20 to 30 km per hour with a smaller number moving at 30-40 km per hour. The latter speeds indicate that the echoes were birds rather than insects, but insects may have contributed to the overall density of echoes.

 



Estimated


Call

Minimum

Species

Count

Individuals*

American Redstart

32

22

Northern Parula

21

15

Black-and-White Warbler

20

12

Magnolia Warbler

13

10

Blackburnian Warbler

7

7

Chestnut-sided Warbler

7

6

Solitary Sandpiper

30

5

Yellow-rumped Warbler

6

5

Black-throated Blue Warbler

6

4

Spotted Sandpiper

11

4

White-throated Sparrow

5

4

Common Yellowthroat

4

3

Ovenbird

6

3

Unidentified Warbler

3

3

Unidentified Sparrow

2

2

Unidentified Warbler Genus Setophaga

2

2

Black-throated Green Warbler

1

1

Canada Warbler

1

1

Cape May Warbler

1

1

Nashville Warbler

1

1

Palm Warbler

2

1

Swainson's Thrush

1

1

Unknown Bird

1

1

Total

183

114




* Calls that are more than one minute apart plus calls that are less than one minute apart divided by three and rounded up to nearest whole number



 

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