Glau­cous gulls: The popu­la­ti­on in Sval­bard is under pres­su­re

Rese­ar­chers of the Nor­we­gi­an Polar Insti­tu­te repor­ted about a signi­fi­cant decli­ne of the glau­cous gull popu­la­ti­on on Bear Island, the most important bree­ding area for glau­cous gulls in Sval­bard and the Barents Sea. During the past few deca­des a per­ma­nent decli­ne of the popu­la­ti­on was reco­gni­zed on the island. An exten­ded moni­to­ring shall now find out if this trend can be con­firm­ed for other regi­ons of Sval­bard.

Bes­i­des fac­tors like food shorta­ge and cli­ma­tic chan­ges the reason for the decli­ne is more and more seen in the bird´s incre­asing con­ta­mi­na­ti­on with envi­ron­men­tal toxins (hea­vy metals, PCBs, fluo­ri­ne, …). The birds recei­ve envi­ron­men­tal toxins with their food and accu­mu­la­te them for exam­p­le in their brains and livers whe­re they affect the animal´s health. On Bear Island con­ti­nuous­ly dead and dying birds with a high con­ta­mi­na­ti­on were found. In pre­vious stu­dies Nor­we­gi­an rese­ar­chers found out that glau­cous gulls with a low con­ta­mi­na­ti­on sur­vi­ved with a rela­tively high rate of 91.5 % while only 40-50% of tho­se with a high con­ta­mi­na­ti­on sur­vi­ved the cur­rent sea­son (see also Spitsbergen-Svalbard.com news Glau­cous gulls threa­ten­ed by envi­ron­men­tal toxins from March 2012). As pre­da­tors, stan­ding at the top of the food chain, glau­cous gulls also give a good indi­ca­ti­on for the con­di­ti­on of the eco­sys­tem they live in.

On the Nor­we­gi­an Red List of Threa­ten­ed Spe­ci­es the glau­cous gull popu­la­ti­on in Sval­bard is curr­ent­ly lis­ted as ‘near threa­ten­ed’ (‘nær truet’). If the alar­ming trend on Bear Island will be con­firm­ed for the who­le of Sval­bard, the sta­tus might be upgraded to ‘end­an­ge­red’ (‘truet’). Obser­va­tions in Ice­land and Cana­da also docu­men­ted a signi­fi­cant decli­ne of the glau­cous gull popu­la­ti­on while the popu­la­ti­on in Green­land, Alas­ka and Rus­sia seems to be sta­ble. But for the­se are­as, and espe­ci­al­ly for Rus­sia, the data­ba­se is not suf­fi­ci­ent.

Source: Norsk Polar­in­sti­tutt

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