Category: Alcidae

Can Norwegian and Russian Razorbills Alca torda be identified by their measurements

Razorbill (Alca torda) Science Article 4 abstract Razorbills Alca torda were measured in one Russian and five Norwegian colonies. A comparison with measurements from colonies in Britain, Ireland, Iceland and the Baltic Sea shows a clear correlation with the geographical position of each colony and a clinal increase in size from the south-west to north-east. […]

Diet of Razorbill Alca torda chicks on Gr sholmen, central Baltic Sea

Razorbill (Alca torda) Science Article 6 abstract This paper describes the food of Razorbill Alca torda chicks on Gr sholmen in the central Baltic Sea and concludes that sprats Sprattus sprattus form the main diet, although sandeels Ammodytes sp. in some years constitute up to 22% by number. Clupeids, mainly sprats, are the most important […]


Razorbill (Alca torda) Science Article 10 abstract Intraspecific kleptoparasitism, the stealing of food from members of the same species, has received widespread but mostly superficial attention in the scientific literature. However, the effects of such behavior can be significant. Here we report on high rates of intraspecific kleptoparasitism in the Razorbill Alca torda at the […]

Effects of island isolation and feral mink removal on bird communities (Alca torda) on small islands in the Baltic Sea

Razorbill (Alca torda) Science Article 7 abstract 1.) Predation has been suggested as a major cause affecting survival, reproductive success and behaviour in vertebrate prey populations. The breeding season is a critical phase because the essential difference between selecting the proper nest site may be a question of breeding success and failure. 2.) Islands may […]

Sexual Size Dimorphism and Assortative Mating in Razorbills (Alca torda)

Razorbill (Alca torda) Science Article 1 abstract My primary aim here is to report the first large data set of live, known-sex Razorbills and to identify the degree of sexual size dimorphism in a number of body measurements. This Study is part of a wider project on mating behavior of Razorbills based on color-banded breeding […]

Wear and loss of rings used on Razorbills Alca torda

Razorbill (Alca torda) Science Article 3 abstract On Grasholmen in the central Baltic Sea, 3,583 Razorbill Alca torda chicks were ringed with triangular Incoloy rings, and about half the birds were subsequently resighted. The resightings were used to calculate rates of turned rings, and 119 retrieved rings were used to calculate rates of wear and […]

Survival and age at first breeding in the Razorbill (Alca torda)

Razorbill (Alca torda) Science Article 2 abstract Observations of banded birds on Skokholm were made during daily visits to the cliffs between mid-March and mid-August (1971-73), and the work was continued by the staff of the Bird Observatory in 1974. In one study colony, The Bluffs, visited daily throughout the season, the birds became tame, […]

Sex differences in razorbill Alca torda parent-offspring vocal recognition

Razorbill (Alca torda) Science Article 9 abstract We investigated differences in parent-offspring vocal recognition between males and females in a natural population of razorbills Alca torda, a long-lived and highly social species of auk (Family: Alcidae). Razorbills provide biparental care to their chicks while at the nest site, after which the male is the sole […]

Comparative foraging ecology of planktivorous auklets in relation to ocean physics and prey availability

Parakeet Auklet (aethia psittacula) Science Article 2 abstract tested the hypothesis that the spatial distributions of foraging least, crested and parakeet auklets (aethia pusilla, A. cristatella and A. psittacula, respectively) in the shallow passes of the Aleutian Islands would be determined by physical mechanisms that control near-surface prey concentrations. We recorded currents using an Acoustic […]