PACIFIC & AMERICAN GOLDEN PLOVERS(2017)
- These two closely related species show different vagrancy patterns
- Remarkably: in the UK the situation is different
Figure 1. American Golden Plover, De Putten, Camperduin, The Netherlands, 5 June 2013 (Fred Visscher)
The closely related Pacific (Pluvialis fulva) and American Golden Plover (P. dominica) both regularly turn up in The Netherlands. Both species are currently reviewed by the Dutch rarity committee CDNA. I analysed all accepted records up till and including 2016 to get a better understanding of the differences and similarities in their occurrence.
Up till and including 2016 there were 69 accepted records (70 individuals) of Pacific and 48 of American Golden Plover. There are a further 8 records of unidentified lesser golden plovers (P. fulva/dominica), which are not taken into account in this analyses. While Pacific is a bit more common in The Netherlands, the opposite is true for the UK. Since 2006, American is no longer reviewed by the British rarity committee BBRC. In 2005, there were about 4,5 times as many records of American than of Pacific (275 vs. 60 records) (Fraser et al 2007).
Before the turn of the century Pacific was the less rarest of the two, partly due to historical records of birds trapped by so-called wilsterflappers, traditional bird trappers specialised in Golden Plovers (P. apricaria). Between 2000 and 2014 both species were more or less equally rare, but due to the exceptionally good years 2015 (n=7) and 2016 (n=8) Pacific once more took a clear lead (figure 2). Another peak year for Pacific was 2002 (n=7). The best year for American was 2013 (n=6): peak years for both species do not seem to coincide. Since 2000 there has only been one year without any records of Pacific (2003), whereas there were three years without American Golden Plovers (2000, 2005 and 2011).
Figure 2. Records of American (blue; n=49) and Pacific Golden Plovers (orange; n=60) in the Netherlands 1989-2016. There are a further 9 records of Pacific between 1896 and 1939 and one record of American (in 1900).
Both species turn up in all four seasons. Pacific has been recorded in all months, American in all months accept March. Yet, there are a clear differences. Pacific clearly peaks in July and August, when no less than 42 birds were identified (> 60% of all records) vs. only seven American. American however, peaks in spring with 20 records in April and May (>40% of all records). Especially May (16 records) stands out. And with only three records, Pacific is really rare then. With ten records October is the second best month for American, while there are only three October records for Pacific. With American still mostly in summer plumage, they more or less stand out in autumn flocks of Golden Plovers.
Figure 3. Number of records of Pacific (orange; n=69) and American Golden Plovers (blue; n=48) per month in The Netherlands 1896-2016. The dark colours indicate the months in which the birds were found, the paler colours indicate birds that were still present in the month(s) after they were found.
With 80 % of all records, Friesland, Noord-Holland and to a lesser degree Zeeland are by far the best provinces for these two species (table 1). Zuid-Holland and Groningen are still quite good and together with Limburg (the latter with one of each) these are the only other provinces were both species have been recorded. Both Utrecht and Drenthe are still waiting for their first lesser golden plover. The Dutch island of Texel, Noord-Holland is by far the best place, with 13 Pacific (14 birds) and nine American Golden Plover records. De Lauwersmeer (Friesland/Groningen) is also very good, with eight Pacific, two American and one unidentified lesser golden plover. Only one of these birds (an American) was seen on the Groningen side of the reserve, all other birds were recorded in Friesland.
Table 1. Number of records of Pacific, American and unidentified lesser golden plovers per provincie in The Netherlands 1896-2016
In The Netherlands, Pacific Golden Plover is a bit less rare than American. That's remarkable, since the opposite is true for the UK. Though both species have been seen in all four seasons, their (average) timing differs: Pacific peaks in July and August, whereas American peaks in spring (mainly May, when Pacific is rare) and October. Friesland (especially Lauwersmeer) and Noord-Holland (especially Texel) are the best areas in Holland to see one.
Fraser PA, M J Rogers & the Rarities Committee. 2007. Report on rare birds in Great Britain in 2005: Part 1:non-passerines. British Birds 100, 16–61