Environmental and Social Research

John F. Kearney & Associates

Unusual Numbers of Shorebirds in Nova Scotia in May 2016 --- A Possible Explanation


Below are three wind maps of the North Atlantic at 2100 hours on 5 to 7 May 2016. The first map also shows the winter ranges of some of the species that were present in higher than normal numbers in May 2016. The unusual sightings also included two Curlew Sandpipers on the afternoon of 7 May.

Normally, in the spring, shorebirds travel up the Atlantic Coast of Nova Scotia to breeding grounds in the Canadian boreal and arctic regions, keeping west of Nova Scotia. At the time that shorebirds on their wintering areas might have been taking off for a nocturnal flight on 5 May, winds would have likely made them drift southeastward from the shores of the southeast United States and northeastward from the Caribbean. It is also possible that any shorebird on the west coast of Africa that had wandered to the west, could have been pulled into the weather system over the western Atlantic. Wind speeds at this hour ranged from 20 km/hr (blue-green colour) to 40 km/hr (green colour) to 100 km/hr (orange colour). The black arrows indicate wind direction.


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Wind Map for 5 May 2016 at 2100 Hours (Atlantic Time Zone) at 850 Millibar Level (about 1500 Meters)

The second map (below) shows wind conditions 24 hours later at 2100 on 6 May. Shorebirds that had drifted out to sea would now be more than halfway to Nova Scotia with a south tail wind pushing them towards the province.

Wind Map for 6 May 2016 at 2100 Hours (Atlantic Time Zone) at 850 Millibar Level (about 1500 Meters)

6_May_2100_hrs.jpg

The third map below shows wind conditions at 2100 hours on 7 May. Birds departing on 5 May would have arrived in Nova Scotia earlier in the day while others would be coming in on 8 May. As shown in the wind map, these later birds would still have a southerly tail wind. According to records in eBird, peak abundance of shorebirds occurred on 8 May but it appears that many remained in the province for a couple of weeks or more.

7_May_2100_Hours.jpg

Wind Map for 7 May 2016 at 2100 Hours (Atlantic Time Zone) at 850 Millibar Level (about 1500 Meters)