Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2011 )

Coordinators:
Jean-Michel Sauvage (France)
Mars Muusse (the Netherlands)

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Herring Gull plumages:

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Herring Gull - 2cy April

Introduction

In spring, 2CY (1st winter / 1st cycle) Herring Gull are still most in juvenile plumage, only the scapulars and mantle replaced for 2nd gen feathers, and to a variable extent feathers on the head, neck, breast and flanks have been replaced as well. Flight feathers (primaries, secondaries and rectrices) are still juvenile, the tertials are still juvenile and the entire wing covert panel is still juvenile (in over 95% of the birds, the odd bird has replaced up to just a few coverts). By April the juvenile feathers, especially wing coverts, are very worn and abraded; the white parts of the coverts merely worn away and the brown parts faded and bleached.

The pattern on coverts and tertials is sometimes hard to tell, due to this bleaching and wear. Below are two ringed birds, argenteus and argentatus from an earlier date, when most of the pattern is still obvious, also on the white parts of the feathers.

above: Herring Gull (argenteus) SR 1CY, September 17 2013, Katwijk, the Netherlands (Mars Muusse). US=1-25%, LS=0%, TOT SCAPS=1-25%. The partial autumn moult in argenteus (moult from juvenile plumage into so-called "first winter" plumage) includes the scapulars, body and head feathers. This moult starts as soon as the nest is abandoned (late June) and continues until January. In general, the head turns paler on throat and forehead. The breast will turn paler as well. The feathers on belly and vent will still be juvenile in most 1cy argenteus by November. From July onwards, juveniles replace the mantle and upper scapulars, moulted to second generation feathers, showing an anchor pattern and a dark base. The lowest row of scapulars are still juvenile by March in most 2cy birds from northern origin (contra e.g. michahellis). The notched pattern of the juvenile scapulars is repeated on the juvenile lesser, lower lesser and median coverts, although the medians have paler centres. The juvenile greater coverts show a 'piano-key' pattern; on the outer greater coverts as well. The tertials have an obvious notched pale fringe and transversal bar.  The juvenile wing-coverts, rectrices and remiges start to bleach and show wear in the fringes from September onwards. The secondaries, primaries and primary coverts are dark with a small white tip, but the juvenile inner primaries show an obvious pale window, prominent from below and above. The under-wing is rather uniform grey-brown patterned. The tail has a broad sub-terminal band and isolated dark bars on the basal half. The iris is dark, the bill is blackish, sometimes with a paler base, and the legs are flesh-pink. below: Herring Gull (argentatus) ES-14266 1CY, October 22 2012, Scheveningen, the Netherlands (Mars Muusse). From Murmansk, N Russia. Only single feathers replaced. North Scandinavian and N Russia birds often remarkable fresh plumage well into January. Here: US: 1-25%, LS: 0%, TOT SCAPS: 1-25%.

By November most argenteus Herring Gull have acquired the 1st winter / 1st cycle plumage, that doesn't change much anymore over the next four months. This is illustrated by the British bird red VLC below. By December, the first sighs of wear are apperent in the fringes of the tertials. By April, see blue CGAR below, most of the coverts are worn as well.

above: Herring Gull (argenteus) VLC 1CY, December 03 2012, Boulogne-sur-Mer, France (Jean-Michel Sauvage). From Suffolk, UK. Much white in last acquired lower scapulars. below: Herring Gull (argenteus) CGAR 2CY, April 05 2009, Boulogne-sur-Mer, France (Jean-Michel Sauvage). From Belgium. No obvious grey-based new scapulars. Note wear in wing coverts and tertial tips.

2CY Herring Gull vs other taxa in April

Within its range, the most likely confusion between Herring Gull and other taxa are Yellow-legged and Caspian Gull. To a lesser extent, they may sometimes be similar to Great and Lesser Black-backed Gull, but normally size (Great Black-backed) and overall dark chocolate brown plumage and inner primaries (Lesser Black-backed) make identification relatively easy.
One of the key features in 1st winter / 1st cycle michahellis and cachinnans is the more extensive post-juvenile moult, which often includes some (or many) of the inner wing coverts and upper tertials as well. Hence, any 2CY bird in April with replaced coverts and tertials is worth checking for other features, and probably will not be a Herring Gull.

above: Yellow-legged Gull (michahellis) S45N 2CY, April 18 2011, Krk, Croatia (Wolfgang Schweighofer). From Croatia. Many inner wing-coverts and the upper tertials replaced in partial autumn moult half a year ago. The pattern on the juvenile wing coverts is completely lost due to wear and bleaching, now faded brown lacking any paler parts. below: Caspian Gull (cachinnans) DN-28100 2CY, April 25 2013, Minden, Germany (Armin Deutsch). From Poland. By spring 2CY cachinnans is extensively bleached and worn, making it hard to be certain about the exact post-juvenile moult. Note very white-headed, with just thin streaking in lower hind-neck. Last acquired scapulars normally greyish in cachinnans, with only very thin pattern. Overall pale plumage and note parallel bill.

Below, comparison with the two Black-backed Gull species in 2CY April plumage.

above: Great Black-backed Gull (marinus) JW999 2CY, April 24 2012, Boulogne sur Mer, France (Jean-Michel Sauvage). From Norway. Coverts and tertials juvenile, the pale parts worn away. Note the bold transversal lines on the rear lower scapulars, and note the head shape with its characteristic bulbous bill. below: Lesser Black-backed Gull (graellsii) 2J 2CY, April 18 2009, Madrid, Spain (Gabriel Martín). Several dark grey 2nd gen feathers in wing-covert panel, scapulars with similar dark grey feathers, primaries very dark brown, more elegant built and brown tone in juvenile coverts darker than in Herring Gull.

Within Western Europe, 2CY Herring Gull in April is a common species, usually the standard, widespread taxon, normally not difficult to identify but with some individual variation. Still its a challenge to identify its from the American cousin and rare vagrant smithsonianus, American Herring Gull. Smithsonianus has an argentatus look, bulkier than argenteus with more snouty head profile. Key features to look for are densely barred rump and upper-tail coverts, dense barring on under-tail coverts, and (almost) completely dark tail, including proximal parts of R5 and R6, the two outermost rectrices. In spring, classic American Herring Gull still has a diffuse, greyish-brown neck collar, where most European birds have fine streaking. The overall brown aspect and texture often continues on the side of breast, even to the flanks on many birds. Below some example birds.

above: American Herring Gull (smithsonianus) 2CY, April 17 2012, Gloucester, MA, USA (Keith Mueller). Feathers in the lowest row of scapulars still juvenile, old and abraded. Note fresh feathers in side of the neck and side of the breast, replaced recently and obviously grey, contrasting with warmer brown old feathers. below: American Herring Gull (smithsonianus) 2CY, April 11 2012, Hammond, IN, USA (Amar Ayyash). Complete moult not started, P1 still present. Note largely dark tail and densely barred upper-tail coverts.

below: European Herring Gull (argentatus / argenteus) 2CY, April 11 2014, Katwijk, the Netherlands (Mars Muusse). Juvenile flight feathers and coverts. Scapulars replaced. Note banded pattern on tail, with base of feathers largely pure white and only diffuse and thin lining on upper-tail coverts. Note also fine streaking in neck and spots on side of breast and flank.

2cy Herring Gull April: tables and charts

April-Chart 1 (below): 2cy HG primary scores in 2002, except May 11 & 26 from 2001 (n = 903). Data as in table 2. Chart 1 shows the early primary moult stage for 2cy Herring Gull; the complete spring - summer figure is plotted in chart 2.

April-Chart 2 (below): 2cy HG primary scores in 2002 and 2001 (n = 2.632). Cumulative data plot for primary moult in spring - summer. Plot: remaining old primaries (e.g. 10 = P1-P10 old; 5 = P6-P10 old). Most data from Scheveningen harbour, Netherlands, but also Dannes and Le Portel, NW France. NW France data responsible for some peak values, e.g. July 10 and in late July indicating advanced primary moult stage compared to birds from Scheveningen. One may discuss including such data in this plot.

below: some 2CY Herring Gulls in April, not uncommon to commence the moult in the first week of April, but most still have P1 in place.

rings argenteus: U.K.