Our knowledge of individual bird populations varies greatly. This is true of both population size and population development. A rough estimate of the total number of breeding birds in Iceland is around 10 million breeding pairs. The vast majority of these are seabirds, or around 7.5 million pairs. Nearly all of the largest bird populations in Iceland are seabirds. For some bird species, the breeding population in Iceland numbers in the hundreds of thousands or even in the millions. Most bird populations in Iceland are estimated as being some thousands or tens of thousands of breeding pairs. It is noteworthy how few seabirds are among the species with the smallest populations in Iceland (<1000 pairs).
Many birds, including most seabirds, congregate densely to nest in so-called bird colonies. A total of 4,500 seabird colonies have been documented in Iceland, although many of these host only a single or a very few bird pairs. The birds nesting at the fewest colonies are the Manx shearwater (Puffinus puffinus), at 7 colonies and northern gannet (Morus bassanus), at 9 colonies. The northern fulmar (Fulmarus glacialis) and Arctic tern(Sterna paradisaea) are the most scattered of Iceland’s seabird populations, with around 1,500 colonies each.
Seabird populations in Iceland have experienced significant fluctuation in recent years. Virtually all seabird populations are in decline, with the exception of the northern gannet and the great cormorant (Phalacrocorax carbo). Most waterbird populations, i.e., goose and duck populations, are either stable or increasing. Population development for waders and passerines in Iceland has been less well documented, although it is known that the black-tailed godwit (Limosa limosa) population was increasing until recently. Some forest birds, such as the common redpoll (Acanthis flammea) and Eurasian wren (Troglodytes troglodytes), have increased in numbers due to afforestation efforts in Iceland.
Iceland is an island of global importance for many bird species. In addition to Iceland’s seabirds, large bird populations breed here that rely on open areas. These include Europe’s largest populations of European golden plover (Pluvialis apricaria), whimbrel (Numenius phaeopus), and dunlin (Calidris alpina).
Ævar Petersen 2008. Iceland. Pg. 19–22 In Petersen, A., D. Irons, T. Anker-Nilssen, Y. Artukhin, R. Barrett, D. Boertmann, C. Egevang, M.V. Gavrilo, G. Gilchrist, M. Hario, M. Mallory, A. Mosbech, B. Olsen, H. Osterblom, G. Robertson and H. Strøm 2008. Framework for a Circumpolar Arctic Seabird Monitoring Network. CAFFs Circumpolar Biodiversity Monitoring Program. CAFF CBMP Report no. 15.