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 2018


Including Morning Flight

Cape Forchu, Yarmouth County, Nova Scotia

N43.80028 W66.16320

Weekly Reports at Cape Forchu for the Spring 2018



4thWeek of May



The outstanding event in nocturnal migration this week was the unprecedented morning flight of nocturnal migrants, mostly warblers, at Tadoussac, Quebec, on May 28th. An estimated 700,000 warblers were seen heading southwest along the Upper North Shore of Quebec. There was considerable press coverage including an article in the New York Times. This event confirms and sheds further light on some of the characteristics of nocturnal migration at Cape Forchu this spring.


     1. The birds at Tadoussac were flying away from the wide of expanse of the St-Lawrence River northeast of Tadoussac toward the much narrower portion of the river near Quebec City. This is consistent with the apparent reluctance of nocturnal migrants to cross expansive bodies of water to Southwest Nova Scotia in the spring.


     2. The birds poured through the Tadoussac region (Saguenay) within a short time frame in the last week of May. The number of nocturnal migrants at Cape Forchu were 3 to 4 times greater in the last week of May compared to any other week from late April onwards. Thus spring migration is highly concentrated, especially as it pertains to warbler migration.


     3. The very high number of nocturnal migrants at Tadoussac and the very low numbers of nocturnal migrants at Cape Forchu in the spring migration indicate that most boreal-nesting birds by-pass Nova Scotia in the spring, migrating primarily up the mainland of the East Coast, much like shorebirds.


     4. The huge number of birds arriving along the Upper North Shore of Quebec throughout the morning is supportive of the observations at Cape Forchu that more birds in the spring often arrived in the early morning hours after sunrise rather than in the pre-dawn period.


Detailed information for Cape Forchu for the last week of May can be found in the tables below.







3rdWeek of May



This week’s monitoring provided further evidence that more nocturnal spring migrants arrive to coastal southwest Nova Scotia one to three hours after civil sunrise than before first light. By civil sunrise on 18 May and 21 May only 3 to 4 warblers were heard during each of these nights. In contrast, in the 1 to 3 hours after civil sunrise, up to 19 warblers of 7 species and 27 warblers of 8 species were heard on these dates respectively during the 3 5-minute count periods. Except for Black-throated Green Warbler and Yellow-rumped Warbler, most of the warbler sounds heard were night flight calls rather than chip calls or songs. This would indicate that these warblers were still on the move. The migrating warblers included Blackpoll Warbler, Magnolia Warbler, Yellow Warbler, American Redstart, Black-throated Blue Warbler, Blackburnian Warbler, Common Yellowthroat, and Cape May Warbler.


The calls of a few Leach’s Storm-Petrels were again captured this week. One of the best recordings can be heard here. If you have not heard this bird before, it is worth a listen!


A flock of Common Terns were heard arriving at 2202 hours on 15 May. It was estimated that there were at least 11 birds, perhaps up to 30.


A chattering Baltimore Oriole was heard on the morning of 21 May.


A rare bird of the week included a singing Field Sparrow. The bird was heard at a distance throughout the morning of 21 May. One recording can be heard here.


Further information for this week can be found in the tables below.





2ndWeek of May


While remaining light in intensity, nocturnal migration provided evidence of the arrival of early May warblers including Black-and-White Warbler, Northern Parula, Ovenbird, and Common Yellowthroat. An early Swainson’s Thrush was recorded at 0118 hours on 14 May and one was heard singing at a distance the following morning; likely the same bird.


The offshore fly-by of the week was a single Leach’s Storm-Petrel at 2340 hours on 12 May. The distant call of this petrel can be heard here.


The morning recordings reflected the arrival of warblers with Cape May Warbler, Nashville Warbler, and Black-throated Green Warbler added to the list of those noted in nocturnal recordings. The migration of White-throated Sparrows remained strong but down somewhat in intensity from last week. With 24 species in the recordings for the week, it was the highest diversity so far this year and was up 50% from the previous week.


Detailed information on the nocturnal and morning recordings can be found in the tables below.






1st Week of May


Nocturnal migration was light again this week. White-throated Sparrows and Savannah Sparrows made up most of the 35 calls recorded.


The morning recordings presented good evidence that many migrants were arriving in the early morning rather than during the night. Recordings on the morning of 5 and 7 May consisted of high numbers of White-throated Sparrow flight calls. In both cases, calls were concentrated in the third hour after civil sunrise (about 07:30-07:45 hours) with generally much fewer calls in other hours. A total of 69 White-throated Sparrow flight calls were recorded between 07:37 and 07:42 on 7 May. There were only 6 flight calls recorded during the preceding night.

An American Oystercatcher was recorded flying past Cape Forchu on the morning on 2 May at 00:12 hours. The justification for this identification and the recording itself can be found here.


Detailed information on the nocturnal and morning recordings can be found in the four tables below.






4thWeek of April


The number of nocturnal flight calls increased considerably this week compared to the previous weeks of April. Nonetheless, total numbers were quite light and may be due to a variety of factors including the lower density of migration and higher flight altitudes in the spring, and a greater reluctance to fly over the ocean in the early spring. For example, the strongest nocturnal migration at Cape Forchu to date occurred when very light surface winds (3-7 km/hr) over the Gulf of Maine on the night of 28-29 April may have allowed birds to safely make a water crossing.


The species composition of nocturnal migration well represented the spring arrivals in the morning counts; Hermit Thrush, Palm Warbler, Yellow-rumped Warbler, White-throated Sparrow, and Savannah Sparrow (compare first second tables below).


The frequency table for the month of April (4th table below) shows some patterns in the timing of migration for various species. Golden-crowned Kinglets and Song Sparrows peaked from April 11-20, Northern Flicker, Winter Wren, American Robin, and Dark-eyed Junco from April 21-25, and Palm Warbler and White-throated Sparrow from April 26-30 (and perhaps continuing into May).


The only rare bird for the month at the monitoring station was the recording of about 9 Snow Bunting on the morning of 22 April.


Detailed information can be found in the four tables below.




3rdWeek of April


Nocturnal migration was again very sparse, but the few calls marked the onset of the migration of Savannah Sparrows and Hermit Thrushes.


Morning counts heralded the arrival of Winter Wren and Palm Warbler. There was an increasing loudness to the morning chorus of American Robins, Song Sparrows, and Winter Wrens. Highest activity was on 19 to 21 April.


All results for the nocturnal and morning counts are summarized in the four table below.



2ndWeek of April