Sunday, 9 September 2018

Summering Gulls in Limerick City

The River Shannon in Limerick City attracts large numbers of gulls outside of the breeding season. Black-headed Gulls with a peak count of 1,628 in mid winter tops the list followed by Common Gulls (peak count 80), Herring Gulls (peak count 66) and Lesser Black-backed Gulls (peak count 25).  Outside of these commoner species, Iceland, Great Black-backed, Glaucous, Yellow-legged, Mediterranean and Ring-billed Gulls all occur in single figures most years.

As one would expect the situation changes dramatically during the breeding season.  About 90% of the Black-headed Gulls disappear along with virtually all of the Common Gulls. The Herring Gull numbers don't vary much, as a number of pairs breed locally on City roof tops. Virtually all of the scarcer species also disappear, however numbers of Lesser Black-backed Gulls appear to have increased noticeably in recent years.

Very low flows in the Shannon this summer combined with low tides exposed large rock outcrops and gravelly stretches in the river bed.  These areas have proved attractive to roosting gulls and provided an opportunity to estimate the numbers involved.  A count on August 13th last produced a surprisingly large total of 882 Lesser Black-backed Gulls.  The majority of these were 2nd calendar year birds with smaller numbers of juvenile (about 10%) and older birds.  The 2CY birds were in widely varying stages of moult.

Four 2nd CY birds showing varying moult progression

A colour ringed juvenile first seen in the City on 11/8/18, (Blue 005:R), was ringed as a chick at the north-eastern end of Lough Ree in Co. Longford on 29/6/18. This was a fairly quick dispersal from the breeding colony and was the fourth report of a colour ringed bird from a newly established ringed project run by Brian Burke on Lough Ree.
Juvenile Lesser Black-backed Gull (Blue 005:R) from Lough Ree, Co. Longford

Fresh Juveniles

Several mature adult Lesser Black-backs were visible all summer so it seems likely that a few at least bred locally.

The first juvenile Black-headed Gulls started to appear in the City in late July and the first returning Common Gulls were only noted in late August. These were joined by an adult Mediterranean Gull in early August, an early date for this scarce species in the City.

Moulting adult Mediterranean Gull at Brown's Quay on 11/8/18

This is the first year that a summering Yellow-legged Gull was recorded in the City.  It appears to be one of two 2nd winter birds that were present last winter.

2nd summer (3CY) Yellow-legged Gull

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