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Nearctic passerines reaching the Netherlands in autumn

The Red-eyed Vireo that was found on Texel last Saturday represents (only) the 15th autumn record of a Nearctic passerine for the Netherlands. Wanting to learn more about the conditions in which these birds arrive at this side of the ocean and, more precisely, across the British Isles and the North Sea, I decided to do a bit of research.

Weather conditions, such as the occurrence of fast-moving depressions over the North Atlantic, play an important role in transatlantic vagrancy. However, the association between vagrancy and weather is complex and Nearctic vagrants can arrive in a range of meteorological conditions.

The past two weeks saw the arrival of several Nearctic passerines in Britain and Ireland. Discoveries between 15 and 17 October included a Grey Catbird Dumetella carolinensis in Cornwall, England, a Veery Catharus fuscescens, Swainsons Thrush C ustulatus and Scarlet Tanager Piranga olivacea in Cork, Ireland, and a Baltimore Oriole on the Outer Hebrides, Scotland. From 18 October onwards a few Red-eyed Vireos were found as well (www.rarebird.co.uk).

Before arriving on Texel, the Red-eyed Vireo had probably made landfall somewhere on the British Isles too. A possible scenario is that it reached north-west Ireland in the third week of October after a transatlantic flight of c 3000 km, and that it resumed migration a few days later, crossing the North Sea with a light tailwind. Depicted below are three weather maps, showing that west and northwest winds were prevailing prior to the discovery on Texel.









The interesting question now is whether this is a classic scenario or just coincidence. Therefore, I also looked up what the conditions were like for the other 14 records. I have summarised my findings in the table below. 


Records of Nearctic passerines in the Netherlands in autumn (www.dutchavifauna.nl, Ebels & van Eck (1992), Levering & Keijl 2008).

Date  Location Species Type Possible scenario
28 Sep 1967 Rotterdam
c 21 km from coast
White-throated Sparrow Trapped Some opportunities for crossing Atlantic during 2nd and 3rd week of Sep. Journey perhaps (partly) ship-assisted, considering location.
8 Oct 1967 Vlaardingen
c 15 km from coast
White-throated Sparrow Trapped (Again) some opportunities for crossing Atlantic during late Sep and early Oct. Journey perhaps (partly) ship-assisted, considering location.
13 Oct 1985 Wormerveer
c 14 km from coast
Red-eyed Vireo Dead Favourable conditions for crossing Atlantic on 7-9 Oct. Possibly resuming migration on 12 Oct, crossing North Sea with light tailwind. Found freshly dead as window collision victim.
19 Oct 1985 Rottumerplaat
c 1 km from coast
Red-eyed Vireo Trapped Favourable conditions for crossing Atlantic on 7-9 Oct. Several opportunities for crossing North Sea on later days. NW winds prevailing on 17-19 Oct, supporting recent arrival on Rottumerplaat.
14-20 Oct 1987 Vlieland
c 1 km from coast
Baltimore Oriole Trapped Some opportunities for crossing Atlantic during 1st week of Oct. Some opportunities for crossing North Sea on later days. Bird's fat score (2) indicated it had taken some time to refuel.
16-23 Oct 1988 Schiermonnikoog
c 2 km from coast
Northern Mockingbird Sighting Quite a few opportunies for crossing Atlantic during late Sep and early Oct. SE winds prevailing on 11-16 Oct, suggesting bird may have been present for a few days before being found.
24 Sep 1991 Vlieland
c 1 km from coast
Red-eyed Vireo Trapped Favourable conditions for crossing Atlantic and North Sea on 18-24 Sep. W winds prevailing on 22-24 Sep, supporting recent arrival on Vlieland.
2 Oct 1991 Vlieland
c 1 km from coast
Red-eyed Vireo Trapped (Again) favourable conditions for crossing Atlantic and North Sea between 28 Sep and 2 Oct.
3-8 Oct 1996 Vlieland
c 2 km from coast
Red-eyed Vireo Sighting Quite a few opportunities for crossing Atlantic during final 10 days of Sep. Possibly resuming migration on 1-2 Oct, crossing North Sea with light tailwind.
13-15 Oct 1996 Vlieland
c 1 km from coast
Myrtle Warbler Sighting Quite a few opportunities for crossing Atlantic during 1-10 Oct. S winds prevailing on 11-13 Oct, suggesting bird may have been present for a few days before being found.
13 Oct 2001 Schiermonnikoog
c 2 km from coast
Red-eyed Vireo Trapped Some opportunities for crossing Atlantic and North Sea during 1st and 2nd week of Oct.
22 Oct 2003 Castricum
c 1 km from coast
Red-eyed Vireo Trapped Some opportunities for crossing Atlantic, particularly on 6-9 Oct. Some opportunities for crossing North Sea on later days. Bird's fat score (3) indicated it had taken some time to refuel.
9 Oct 2005 Westkapelle
c 1 km from coast
Red-eyed Vireo Sighting Quite a few opportunities for crossing Atlantic during late Sep and early Oct. Possibly resuming migration on 8 Oct, crossing North Sea with light tailwind.
18-21 Sep 2010 Vlieland
c 1 km from coast
Northern Waterthrush Sighting Some opportunities for crossing Atlantic during 2nd week of Sep. NW winds prevailing on 15-18 Sep, supporting recent arrival on Vlieland.
27-30 Oct 2018 Texel
c 3 km from coast
Red-eyed Vireo Sighting Quite a few opportunities for crossing Atlantic during 3rd and 4th week of Oct. NW winds prevailing on 23-27 Oct, supporting recent arrival on Texel.


So what can be concluded from all this?
  • 9 out of 15 Nearctic passerines (60%) reaching the Netherlands in autumn were Red-eyed Vireos. The other species were Northern Mockingbird Mimus polyglottos, White-throated Sparrow Zonotrichia albicollis (2), Baltimore Oriole, Northern Waterthrush and Myrtle Warbler.
  • 12 out of 15 Nearctic passerines (80%) were found right on the coast. The only exceptions were a Red-eyed Vireo found dead in Wormerveer (c 14 km inland) in 1985 and two White-throated Sparrows trapped near Rotterdam (c 15-21 km inland) in 1967.
  • 7 out of 15 Nearctic passerines (c 47%) were found in the north-westernmost part of the Netherlands, all within c 20 km from each other.
  • All records followed after a period with at least some opportunities for successful transatlantic flights and many coincided with records elsewhere in north-western Europe. The conditions, however, were quite variable. Some birds appear to have arrived after an (almost) nonstop flight without spending (much) time on the British Isles, such as the Red-eyed Vireo in September 1991. But many others have clearly taken much longer to filter through, some turning up out of the blue, like the Red-eyed Vireo in October 2003.
Despite increased observer activity, Nearctic passerines reaching the Netherlands in autumn remain very rare. The past 10 years have resulted in just two records. But that is no reason not to have high hopes. Those birds that get the chance to refuel after their long transatlantic journey, will keep coming. All we have to do is find them!




From my 1996 notebook.


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Published 30 October 2018