Ode to April

For the last number of years, I’ve been lucky enough to live just a short hop, skip and jump from Dublin Bay. I’ve always known it was a special place. However, I don’t think I fully appreciated it until these extraordinary times have suddenly (and understandably) restricted my ability to visit it fully. Thankfully, a small portion of the bay, the Tolka Estuary, lies within my 2 km zone.

Tolka Estuary. Credit: Liam Gaynor.

Now that my visits are purely personal rather than as part of our usual DBBP team to collect data, this little slice of the bay has become all important to me. Suddenly I find myself sitting on the grass, whiling away time, watching Black-tailed Godwits partially garbed in rusty breeding plumage. Redshanks scurry frantically amongst them, their incessant calls a reminder of their endearing nickname, the ‘warden of the marsh’. The first calls of Sandwich Terns fresh off the boat from southern Europe and Africa are now a particular cause for celebration as our worlds have shrunk to a two km radius. The immensity of their long-haul migration now seems particularly thrilling compared to our limited movements.  

So, for those unable to get even this close to Dublin Bay, what would be better than to bring the bay to you. This blog serves as replacement of sorts to the DBBP team’s April waterbird surveys, which we naturally were unable to do this month. So instead, as an ‘ode to April’, we’ll take a look at data from previous Aprils of the project to see just how important this month is for waterbirds in the bay. 

Species found in Dublin Bay during low-tide counts in April. The size of the text corresponds to their relative abundance, with larger text indicating higher numbers. 

April is a time of migration both in and out of the bay for waterbirds. Wintering wader and wildfowl numbers decrease significantly from March until June, but seabird numbers begin to increase.  

Sandwich Terns make their first appearance in April. Often heard before they are spotted, these punk-rock superstars herald the beginning of the tern season with their suitably raucous call as they forage over the sea. 

Sandwich Tern. Credit: Brian Sullivan

Common Terns, arriving from as far south as Namibia in Africa, trickle in towards the end of April, their buoyant flight giving credence to their nickname of ‘Sea Swallow’.  

Common Tern. Credit: Brian Burke 

Cormorants, while present year-round in the bay, begin to increase in number in April. Nearly fish-like as they dive, these prehistoric-looking beauties use the weight of water saturating the margins of their feathers to decrease their buoyancy and increase their diving efficiency. 

Cormorant. Credit: Brian Burke 

Numbers of Black-legged Kittiwakes also increase during the month of April. These small, white-headed gulls are principally pelagic (living on the open sea) during the non–breeding season and are the most oceanic of the gull species.  

Black-legged Kittiwake. Credit: Brian Burke

During the breeding season, Kittiwakes nest in colonies which can number from tens to thousands of birds. They are typically found on cliff faces and sea stacks, but have been known to nest on bridges, piers, purpose-built ‘Kittiwake Towers’ and even buildings. See here for a live cam feed of Kittiwakes nesting on the BALTIC Centre for Contemporary Art in Gateshead, England.

Gateshead ‘Kittiwake Tower’. Credit: skyscrapercity.com 

Herring Gulls are the most numerous species found in Dublin Bay in the month of April, just narrowly beating out the nation’s favourite Goose, the Light-bellied Brent Goose, for top place. An afternoon spent watching Herring Gulls dance in your local park is well worth the time. The reverberations of their feet simulating rain draws the earthworms to the surface, where they are promptly gobbled up by the gull. 

Herring Gull. Credit: Brian Burke

 Herring Gulls in Dublin Bay: mean low-tide numbers per month 2013-2019, Dublin Bay Birds Project. 

By the end of April, Light-bellied Brent Geese, our second most abundant species in the bay this month, will have left our shores for the Canadian Arctic. Approximately 95% of this subspecies overwinters in Ireland, placing great responsibility on our shoulders to safeguard the future of this charismatic goose. 

 Light-bellied Brent Geese. Credit: Brian Burke

Light-bellied Brent Geese in Dublin Bay: mean peak numbers per month 2013-2019, Dublin Bay Birds Project. 

The most abundant wading species recorded on average during low-tide counts in April, is the Black-tailed Godwit. In April, the Dublin Bay population is bolstered by Black-tailed Godwits on passage from elsewhere in Ireland and Europe. Breeding in Iceland, these beauties leave Dublin approximately one month later than their cousins, the Bar-tailed Godwit, which breeds in northern Norway. Both species occur in internationally important numbers in Dublin Bay during the winter months.  

Black-tailed Godwit. Credit: Nigel Clark 

Bar-tailed Godwit colour-ringed by the Dublin Bay Birds Project and observed in Norway. Credit: Kim Fischer 

Bar-tailed and Black-tailed Godwits in Dublin Bay: mean peak numbers per month 2013-2019. Dublin Bay Birds Project. 

Oystercatchers are one of the few wading species that do not all but disappear from Dublin Bay during the breeding season. An average of 700 – 800 Oystercatchers have been recorded in May and June over the last six years. Dublin Bay colour-ringed Oystercatchers have been recorded breeding in Ireland, Scotland, Iceland and Norway, with the earliest records of a colour-ringed Oystercatcher returning to its breeding grounds submitted from Scotland on the 14th January 2018 and the 15th January 2020. 

Oystercatcher colour-ringed by the Dublin Bay Birds Project and observed in Iceland. Credit: Oskar Bjornstad 

Oystercatcher numbers in Dublin Bay: mean peak numbers per month 2013-2019, Dublin Bay Birds Project. 

Good numbers of Redshank are still knocking about Dublin Bay in April, although they begin to depart for their Icelandic breeding grounds from March onwards, with very small numbers present in May and June. Unlike most of the wading species, Redshank numbers will peak significantly in September and October when birds on passage from Scandinavia and the Baltic region pass through on their migration to west Africa.   

Redshank colour-ringed by the Dublin Bay Birds Project and observed in Dublin Bay. Credit: Joao de Brito 

Redshank numbers in Dublin Bay: mean peak numbers per month 2013-2019, Dublin Bay Birds Project. 

April is a time of passage migrants, riding the highway of the East Atlantic Flyway. One of the briefest visitors to our shores is the Whimbrel. This curlew-esque wader makes a short pit stop in Ireland in April and May, refuelling before resuming its northward journey. We will see it once more in June and July as it travels southward towards southern Spain and western Africa where it will see out the winter basking in sunshine. See here for a current Whimbrel and Bar-tailed Godwit tracking study in real time.

Whimbrel. Credit: Frank King 

As April melts into May, our wader and wildfowl numbers will continue to drop, but our seabird numbers will climb. Soon cliff faces, sea stacks, beaches, islands and some man-made structures, will be alive and heaving with seabird colonies. From all in the Dublin Bay Team, take heart that although we currently live in uncertain times, nature will carry on and be there when we get back. Like the seasons, this too will pass.