Full-text - Norsk entomologisk forening

tes. This part of the material (28 birds and 29nests) is described in the publications on fleas associatedwith seabirds (Mehl in prep,), Informationabout ticks. «puffin lice». in seabird colonieswere obtained from visitors to the islands ofVcer0y. Bleik, Hjelms0Y and Svcerholtklubben.We assume that these ticks were I. uriae.The techniques used for collecting ticks were:I. «Flagging» on stones and vegetation with apiece of terry cloth, I x 0.5 m, attached to astick. 2. Turning stones and other loose objectsin colonies of puffins or shags, in rock-strewnslopes and under steep bird cliffs. 3. Visual examinationfor ticks in teased nest material in awhite plastic tray. 4. Maintaining nests andgrass in double polyethylene bags and waitingfor the parasites to crawl out, as described byMeW (I 970).Birds, adults and nestlings, were collected byhand, in nets, or were shot. Nestlings from R0Stfrom July 22 and 27 1979 had fallen from theirnests in the cliffs during a three hour period inthe middle of the night. All birds were placed inseparate plastic bags containing a piece of cottonwith chloroform and subsequently examined forticks and other ectoparasites as described byMehl (1970). Blood samples were obtained bycardiac puncture. The birds were stored frozen.Most of the petrels were examined alive and released.The examination of seabirds for ticks is difficultand time consuming mainly because of thethick layer of down covering their bodies. Consequently,small ticks are easily overlooked. Itwas found that ticks were easier to detect whenthe down was slightly moistened with ethanol.Thicks used for virus isolation attemps weremaintained in glass vials containing moistenedplaster of Paris or a green straw, and stored in arefrigerator.We did not climb the steep bird cliffs and thusthe nesting material which we collected comesfrom the more accessible sites. A total of 63nests and 246 birds (66 nestlings) were examined.A total of 1350 ticks were collected, and ofthese 206 were used for virus isolation.Ecological aspects of bird cliffs and nests ashabitats for ticksKittiwakes, Rissa tridactyla, fulmars, Fulmarusglacialis, razorbills, Alca torda, guillemots Uriaaalge, puffins, Fratercula arctica, gannets Sulabassana, shags Phalacrocorax aristotelis andcormorants Phalacrocorax carbo breed in colonieson steep, rugged cliffs along the west andnorth coast of Norway. These bird cliffs may beoccupied by a single species, such as with puffinsin Lovunden, or more commonly by severalspecies nesting in their typical habitats. The coloniesmay number from 20 to more than100.000 pairs. (Haftorn 1971, Brun 1978, Eld0Y1982, Tschanz & Barth 1978).The same nesting sites are usually occupiedyear after year. The birds nest close together,from a few decimeters to a few meters apart.The birds exert strong modifying effects ontheir nesting habitats with their nest material,excrements and burrowing acitivites. Furthermorethe vegetation on and around the cliffs isstrongly influenced by the fertilization effects ofthe excrements (Goks0yr 1938, Gf0nlie 1948).Short descriptions of the nests of birds as habitatsfor parasites are given below:The kittiwake constructs a cupshaped structureconsisting mostly of terrestrial vegetation •and some seaweed, on tiny ledges in the steepestparts of the cliffs. The depression' in the nest isdeep and dry during the incubation period andwhen the nestlings are small, but subsequentlybecomes trampled flat and soiled sith excrements.The original nests are further built uponduring several seasons and can become quite •large. The incubation period lasts for 21 to 24days. The fledglings leave the nest around August10th, when they are about five weeks old.Pairs having neither eggs nor nestlings may occupytheir nests for several weeks during thebreeding season.The shag breeds at the foot of sea cliffs and onisolated rock stacks and islands. The nests are situatedbelow rock falls or in rock clefts, andconsist mainly of large algae which is lined withfresh grasslike vegetation. The cup of the nest remainsdry as long as eggs or small nestlings arepresent. Thereafter, it becomes trampled and soiledwith excrements. The nest and its immediatesurroundings are often moist and slimy dueto excrements and rotting algae. However, drynesting material can be found in the cracks andcrevices around the well protected nests, andthis appears to be the best microhabitat for ticksand fleas. The incubation period lasts for24 - 28 days and the young are fledged whenthey are 4-5 weeks old. Large age variationscan occur among nestlings in the same colony.The puffin lays a single egg at the end of crevicesin the rock slides or else in burrows whichthey have dug in the steep grassy slopes. Thenests consist mainly of grass. The floor of theburrows is damp and hardpacked whereas the96