Attracting Terns.

It goes without saying that the vast majority of holidaymakers will make their holidays on the coast, and the Victorians were no exception. North East Wales once had a booming tourism industry, owing to the large expanses of sandy beaches that stretch almost uninterrupted from the Dee estuary to Llandudno, and the relative ease of access from the cities of North West England.

Apart from a couple of brief periods when Britain was consumed by War, recreational use of the North Wales coast increased during the 20th century. Peaking in the 70s and 80s when owning a caravan in Prestatyn was regarded as a social prestige, development has dramatically changed the coastline. From what would have been extensive sand dune and salt marsh systems, we now have hard sea defences and promenades.

We are quite fortunate then, that the remnant sand dunes west of the Dee estuary (known collectively as the Gronant Dunes and Talacre warren SSSI) are still outperforming their man made competition, both in terms of biodiversity and their ability to resist storm surges, further west. It is here of course that the last colony of Little Terns in Wales have been nesting for over 100 years, and have been actively protected since 1975.

Talacre Warren and Gronant Dunes SSSI - Last remnant sand dune system in North East Wales

So why then, does this all too fussy species choose to come back to Gronant year on year? and why do they choose to nest on ground so prone to flooding?  As with most explanations of a species' natural history, the answers are many and is down to a contribution of factors. I've split them up into separate blog posts, starting with the most basic need of a sea  bird.

Food

As their name suggests, the Little Tern is Europe's smallest breeding Tern species, and small birds, require small food. Adult terns feed on a variety of prey in their lifetime, including small crustaceans annelid worms, pelagic molluscs, insects (dragon flies, grasshoppers, flies, gnats) and other invertebrates, but mainly on small, oily fish. The young, however, are almost exclusively fed on small fish.

Little Tern with a Sand Eel at Gronant - Fish are also used exclusively
for courtship and mating performances - Males attract females down to the
shingle with a fish, females may then accept this gift without providing with
their end of the bargain

Little Terns will generally forage for smaller fish than Common, Arctic and Sandwich Terns, their larger relatives. And unlike other seabird breeding colonies further north, there has never been a recorded issue with food availability at Gronant. Chick growth rates are limited only by their metabolism, and chicks are often seen refusing food (Norman, 94). The Dee estuary has one of the highest tidal ranges in Europe, and the strong currents that come in with the tide, and comparatively weaker currents on the way out is what's responsible for depositing sand and shingle higher up the beach. This forms safe nesting habitat for shore birds, but also creates a shallow sea. This shallow sea close to the shore at Gronant provides habitat for small fish such as sand eel to thrive, and thus, excellent foraging grounds for Little Terns.

Embryo sand dune, shingle ridge and shallow shore at low tide, Gronant.
West-East Long Shore Drift is responsible for constantly dumping new material -sand and stone - on the beach.
This process must continue to provide nesting habitat for the Little Tern in the future.

The proximity of food source is very important for this species, they are thought to forage no further than 5km from their nesting site. There are also other foraging opportunities for the Little Terns close by; adults are often seen fishing in the lagoon at the rear of the dunes, and also in the salt marsh creak, less than 50m from some nests.

In contrast, the reduction of larger food sources in other local areas has been suggested as a cause for the decline of a Common Tern colony, further east at Point-of-Ayr. Though this has not yet been studied.

The more experienced adult Little Terns will remember that there is an abundance of food here, close by, and this will attract them back year on year. Historically, little terns were not thought to be site-faithful, however, the gradual increase of breeding pairs over the years, and the relative isolation of the Gronant colony suggests that the majority of our terns do return to their natal grounds to breed. However, some birds ringed at Gronant have been recovered elsewhere, and visa-versa, this contradiction will hopefully become more clear as a new colour ringing programme, developed by the EU Life+ Little Tern Recovery Project gets underway next year.