Biology / ecology
The Common Tern (Sterna hirundo) is a bird in the sternidae family. Medium in size, it is fairly easily distinguished from the other two main species of terns in France by its bright red beak, sometimes orange, ending in a black tip.
Its nesting area is very wide, North America, Atlantic islands, Europe, West Africa, Middle East. He is a strict migrant who winters on the African coast.
The Common Tern is essentially subservient to aquatic environments.
In France, it is observed from the beginning of April, its distribution being both coastal and fluvial. The colonies are present in small numbers on all the coasts as well as on the Loire and the Allier.
It nests mainly on sandy islets with little vegetation, but also on artificial structures, dikes, rafts, factory roofs. Colonial and gregarious species, it forms groups of a few individuals to several hundred couples, sometimes in mixed colony with avocets, seagulls or other terns.
Essentially fish-eating, it captures its prey, small fish, sometimes shrimp, by diving to the surface. Very occasionally it feeds on insects. Adults can make trips of several kilometers depending on the availability of prey.
It nests directly on the ground in a very basic nest, often a simple bowl, in which it lays one to three eggs. After three weeks of incubation, the young semi-homeless remain close to the nest and are fed by both parents for more than three weeks. Egg laying generally takes place from April to June. If the eggs or the young are destroyed, the individuals are able to lay eggs for replacement, and it is not uncommon to observe the last young in flight in early September.
Quite soon after takeoff, the families leave the breeding site, before starting their migration in September-October.
Protection and conservation status
The Common Tern is a protected species, listed in Annex I of the Birds Directive.
Its conservation status is considered to be of minor concern on a French, European and global scale. However, since reproductive success is generally very low, numbers may fluctuate greatly.
In France, the breeding numbers, stable or even slightly increasing in recent years, fluctuate between 5,000 and 6,000 pairs. The Pays-de-la-Loire region hosts a large part of the national population with around 20% of the population and has a strong responsibility for this species.
Distribution and status of populations on Natura 2000 sites
The Common Tern is well represented on the Natura 2000 sites targeted by LIFE Sallina, with 300-400 pairs on the Ile de Noirmoutier / Breton marsh and nearly 170 pairs on the Guérande and Mès marshes (Living Brittany, 2019), i.e. almost 20% of the regional workforce.
The number of favorable sites, particularly sheltered from human disturbance, is low. Protected areas therefore play an important role, in particular the Regional Natural Reserve of the Polder de Sébastopol (Barbâtre) regularly welcoming more than 300 couples.
Due to the large share of nesting staff, the 3 Natura 2000 sites of LIFE have a strong responsibility with regard to the tern pierre-garin.
Conservation objectives / threats / actions planned in LIFE
The main threat is related to human disturbance and stray dogs disrupting the establishment of colonies and possibly inducing their abandonment.
The objective is to be able to increase the number of sites favorable for the reproduction of the species.
Restoration work carried out on certain pilot sites within the framework of LIFE Sallina, in particular the creation of islets for the reproduction of the Avocet elegant, will be favorable for the installation of stone terns.
The joint implementation of protection measures is a guarantee of success.