Sections Ornithology 2007 Breeding Season - Autumn 2007
2007 Breeding Season - Autumn 2007
As everyone will be aware, the summer of 2007 has not been a classic one, when it comes to weather.
Breeding success rates for birds have varied widely, depending on the species and how early or late breeding began. Given a good April, birds that started early such as Ravens Corvus corax and Long-eared Owls Asio otus bred well, whereas later started such as Barn Owl Tyto alba, House Martin Delichon urbica and Common Tern Starna hirundowere far less successful.
House Martins though, have more than one brood per season and later attempts were more successful, with young still in the nest in September, when fine weather offered them a good chance of fledging and departing before the onset of winter.
Barn Owls, though, had a poor season, the young suffering high mortality, probably due to starvation, the adults being unable to find sufficient food in the poor weather conditions which prevailed.
On a brighter note, Sand Martins Riparia riparia had one of their most successful years, thanks in no small part to the provision of a new sand face for their nest holes, courtesy of the owners of Simon's Sandpits in St Ouen's Bay, the bird's only breeding location in the Island.
Common Terns were much in the press during the early Summer, for all the wrong reasons. Our colony on Les Ecrehous, failed to establish this year, the birds deserting the area very soon after their arrival, and not returning. Many causes have been put forward for this desertion, such as weather, lack of food and disturbance. It is unlikely that the weather was a major factor in this case as smaller colonies on the south coast of Jersey, did have reasonable breeding success. Certainly there was a bloom of algae around the critical time, making it difficult for the birds to see fish swimming below the surface, but again the other birdes were able to overcome this difficulty. All these factors will have played a part, but disturbance seems the most likely cause. A rapid increase in human disturbance through leisure activities such as eco-tours by boat, private boating and kayaking is putting extra pressure upon these fragile areas and measures need to be put in place to provide proper protection for the birds. That said, another cause of natural disturbance comes in the form of predator species such as Peregrine Falcons, Falco peregrinus, visiting the area to feed from Jersey or France and with the falcon's numbers on the increase, this is considered to be a prime cause of this year's failure. It is unlikely that this can be proved beyond doubt this year, but with this extra knowledge to hand, monitoring of the Common Tern colony next year, may shed more light upon it - assuming, that is, that they return in 2008 to try again.
Mick Dryden - Chairman
