delawarensis Ring-billed Gull

(last update: 10-03-2014 )

Coordinators:
Keith Mueller
Amar Ayyash
Mars Muusse

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adult: March

Ring-billed Gulls vs Common Gulls: comparison from a Dutch perspective - 201402

by: Maartren van Kleinwee (GULLS TO THE HORIZON)- March 06 2014.

Ring-billed Gulls Larus delawarensis are common visitors to Europe with frequent sightings in countries directly bordering the North Atlantic such as Ireland, Spain and Portugal.
Here in the Netherlands however, they are considered rare (see list of observations on Waarneming.nl) and most sightings are quickly uncovered as regular Common Gulls Larus canus due to unfamiliarity by the observer with both Ring-billed Gull and Common Gull.
When I traveled to the USA recently for a short gull-watching trip (see Gull watching in the southern Lake Michigan region (USA) – 201402), one of my aims was to get familiar with Ring-billed Gulls and to find out exactly what differentiates them from Common Gulls.
Below are some personal reflections based on my observations.

Note #1: This article is nothing more than a personal exercise in comparing 2 random groups from both sides of the Atlantic; it should by no means be seen as a definitive comparison between these 2 species; this requires a far higher number of individuals.
Note: #2: All Common Gulls are of unknown origin and photographed in the Netherlands in the months of December, January and February.

Adults

Although it should be quite straight forward to distinguish an adult Ring-billed Gull from a Common Gull, lets compare some of the main features.

Compared to an adult Common Gull, an adult Ring-billed Gull is different in the following aspects:

  • Lighter upper parts
  • A thicker, stouter bill
  • Smaller mirror on P10
  • Smaller mirror on P9 or no mirror on P9 at all
  • Rarely a mirror on P8
  • No black on P4
  • Pale yellow iris
  • Thinner tertial crescent

Bill and eye color comparison

Note that the bill pattern on the Ring-billed Gulls is very distinct, while the ‘ring’ on the bill of a Common Gull is very faint.
Judging the bill shape and size may look straightforward but can be tricky in the field.
Pitfall: Some Common Gulls can show a light iris and should not be treated as a Ring-billed Gull on that feature alone.

Primary pattern

Q. How does the pattern on the primaries help us recognize an Ring-billed Gull in the Netherlands?
A. Any individual without a mirror on P9 should immediately attract attention.

Tertial crescent

Probably one of the key features of spotting an adult Ring-billed Gull in a group of Common Gulls (especially from afar) is its much reduced white tertial crescent.

Vocalization (see/listen also HERE)

The vocalization of Ring-billed is lower in tone, more nasal than Common and reminiscent of Herring Gull.
Unfortunately I don’t have many recordings of Common Gull vocalizations and they don’t match the type of Ring-billed Gull calls that I was able to record in Milwaukee, but I thought it best to include 2 tracks.

Comments

Although this has been a fully unscientific and random comparison, it has nevertheless been a very interesting and useful exercise for me.
It has highlighted some features that I would otherwise not have noticed (such as the barring on the inner primaries in first-cycle birds) and has made me more comfortable in knowing what to look out for should I come across a Ring-billed Gull-candidate here in the Netherlands.
It has been great to observe Ring-billed Gulls in such large groups and from such a short distance. Unfortunately the same cannot be said of Common Gulls and I was surprised with how few photos I had in my archives of this species.
Finally, I hope that my findings are useful for other birders as well.

Locations

The majority of the Ring-billed Gull photos in this article were taken at the beach at the BP refinery at Whiting, Indiana, USA, adjacent to Lake Michigan.

Ring-billed Gull delawarensis A36 adult, March 19 2014, Wethersfield, CT. Picture: Keith Mueller.
Ring-billed Gull delawarensis CH1 adult, March 05 2014, CT landfill. Picture: Keith Mueller.
Ring-billed Gull delawarensis JZ2 6CY, March 20 2014, Stratford, CT. Picture: Donna Rae Henault Caporaso.
Ring-billed Gull delawarensis K0X adult, March 19 2014, Wethersfield, CT. Picture: Keith Mueller.
Ring-billed Gull delawarensis KUF 7CY, March 17 2014, Hammonaset beach, Madison, CT. Picture: Keith Mueller.
Ring-billed Gull delawarensis LKF adult, March 19 2014, South Meriden, CT. Picture: Keith Mueller.
Ring-billed Gull delawarensis X9U adult, March 05 2014, CT landfill. Picture: Keith Mueller.
Ring-billed Gull delawarensis 440 adult, March 01 2010, Print Works Pond, Cranston, RI. Picture: Scott Grant.
Ring-billed Gull delawarensis 643 adult, February - March 2012, Southbury, CT
Ring-billed Gull delawarensis 672 adult, March 05 2014, Shepaug Dam, Southbury, CT. Picture: Keith Mueller.
Ring-billed Gull delawarensis A1081 adult, March & December 2014, Stratford, CT. Picture: Donna Caporaso & Keith Mueller.
Ring-billed Gull delawarensis A21 adult, March 25 2015, Wooster Pond, Stratford, CT. Picture: Frank Mantlik.
Ring-billed Gull delawarensis A74 adult and A75 2nd cycle (3CY), March 08 2014, UMASS Boat Ramp, Lowell, MA. Picture: Anthony L.
Ring-billed Gull delawarensis ?07 adult, March 16 2014, Stratford Boat Ramp - Stratford, CT. Picture: Donna Caporaso.
Ring-billed Gull delawarensis HXP 6CY, March 19 2014, Stratford boat ramp, CT. Picture: Donna Rae Henault Caporaso.
Ring-billed Gull delawarensis TC11 adult, March 24 2014, Toronto, ON. Picture: Amanda Guercio.
Ring-billed Gull delawarensis TC22 adult, March 24 2014, Toronto, ON. Picture: Amanda Guercio.
Ring-billed Gull delawarensis Fed band adult, March 19 2014, Wethersfield, CT. Picture: Keith Mueller.
Ring-billed Gull delawarensis adult, March 2007, Cobourg, Ontario, Canada. Picture: Wikipedia.
Ring-billed Gull delawarensis adult, March 04 2012, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 25 2012. Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 01 2013, Canaveral National Seashore, FL. Picture: Tammy Karr.
Ring-billed Gull delawarensis adult, March 17 2013, Rio Grande, NJ. Picture: Don Freiday.
Ring-billed Gull delawarensis adult, March 01 2013, Canaveral National Seashore, FL. Picture: Tammy Karr.
Ring-billed Gull delawarensis adult, March 01 2013, Canaveral National Seashore, FL. Picture: Tammy Karr.
Ring-billed Gull delawarensis adult, March 10 2009, Gijón, Asturias, Spain. Picture: Luis Mario Arce.
Ring-billed Gull delawarensis adult, March 01 2013, Canaveral National Seashore, FL. Picture: Tammy Karr.
Ring-billed Gull delawarensis adult, March 25 2012. Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 11 2012. Tinley Park, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 27 2012. Oak Forest, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 09 2014, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 04 2010, Virginia Lake, Reno, Washoe Co, Nevada. Picture: Fugle.
Ring-billed Gull delawarensis adult, March 18 2012, Virginia Lake, Reno, Washoe Co, Nevada. Picture: Fugle.
Ring-billed Gull delawarensis adult, March 20 2014, Wethersfield, CT. Picture: Keith Mueller.
Ring-billed Gull delawarensis adult, March 25 2006, Dana Point, Orange Co., CA. Picture: John Avise.
Ring-billed Gull delawarensis adult, March 28 2010, Bray, Wicklow Co., Ireland. Picture: Brendan Marnell.
Ring-billed Gull delawarensis adult, March 09 2014, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 03 2014, Appalachian Counties, Ohio. Picture: Roger Hickey.
Ring-billed Gull delawarensis adult, March 11 2011, Constitution Gardens - Washington, DC. Picture: Mr TinDC.
Ring-billed Gull delawarensis adult, March 17 2013, Mendon, Utah. Picture: Ryan O'Donnell.
Ring-billed Gull delawarensis adult, March 17 2013, Mendon, Utah. Picture: Ryan O'Donnell.
Ring-billed Gull delawarensis adult, March 09 2014, Chicago, IL. Picture: Amar Ayyash.
Ring-billed Gull delawarensis adult, March 09 2014, Chicago, IL. Picture: Amar Ayyash.