April Fowl
As spring
is (almost) turning to summer, there is also a transformation in the bird life
of Dublin Bay. Having spent the winter taking bi-monthly counts of the birds at
Bull Island, I have watched the birds in the lagoon shift with the seasons. Not
only are new species arriving and others heading off around the world, but the
appearance and behaviour of certain species is adjusting to the warmer season.
The
difference most apparent to me were birds coming into their colourful summer
plumage, which is generally much more striking and attractive than winter
plumage (and makes identifying species at distance a much faster task!). Many
of the Black-tailed Godwit have already traded their plain brown winter plumage
for vibrant rufous-orange on the neck and black barring on the breast.
Similarly, Dunlin become a rich chestnut with a prominent black belly patch,
rather than their wintertime grey-brown. The Black-headed Gulls finally live up
to their name and develop a striking chocolate-brown head for the breeding
season. This emergence of birds in full breeding plumage signals the birdy
courtship season is in full swing and summer is truly on its way!
Black-tailed Godwit in breeding plumage (Andrew
Kelly)
Black-headed Gull living up to its name (Oran O’Sullivan)
Dunlin in summer colours (Ken Kinsella)
The
change is not only in appearance but also, of course, in behaviour. As their
migration departure is approaching fast, the Brent Geese at Bull Island are
frantically building stores to see them through the journey. Since they have
spent the winter gorging all the eelgrass and algae in sight, by spring Brent
Geese must look for something new to devour. In the last month I have observed
more geese feeding in the grass around the lagoon instead of the intertidal
zone within the lagoon. Early in winter, the geese feed on eelgrass and algae
at low tide, but when all of it has been eaten away, they begin to graze
grassland. This reflects how the change in vegetation through the seasons
influences the bird life, as some sources become depleted and others are made
available.
Perhaps
the most significant change through the seasons is inward and outward migration
to and from Dublin Bay. By late April, most of the over-wintering species have
left Ireland and summer species are arriving. I have noticed a reduction in wintering
species’ population numbers at Bull Island during April counts, as migration to
their summer grounds gets underway. Smaller numbers of Sanderling, Knot and
Turnstone meander around the lagoon, while Wigeon and Teal in particular have
disappeared off my radar. But the upside to the absence of these birds are the
arrival of summertime species to Bull Island. I spotted my first two Sandwich
Terns of the season pottering around the lagoon just last week - something that
screams “summer is here!!” in my face.
While
my bird counts at Bull Island are finished for this winter season, the spring
transformation is set to continue. More summer species, such as the remaining Terns,
will arrive, and those Brent Geese inhaling the grass will abscond to Canada.
Hopefully this summer will be a kind one to our breeding birds and next
winter’s monthly counts will show positive results!
Susan
Doyle