Baltic Seabirds Transect Surveys

Gediminas Vaitkus, Institute of Ecology of Vilnius University

Seabirds transect surveys were conducted in Baltic Sea from 1992 to 1999. Standard seabird offshore sampling techniques assume that line transect of 300 m width is basically used for counting birds sitting on the water surface, whereas the 'snap-shot' method is used for the counting of flying birds at strongly fixed intervals of time.



Additional efforts were put into studies of the offshore seabird and waterfowl movements. We recorded flying
birds along 1,000 m wide transect over the 'classic' 300 m transect used for calculations of seabird densities
during 'snap-shots'.

The main purpose of our work was to investigate spatial structure and dynamics of the offshore seabird populations and to assess their status in specific conditions of the Baltic Sea marine ecosystem. The main tasks of our work were the following:

-Study species composition, abundance and spatial distribution of seabird populations in different seasons of the year, distinguish dominating species and the most important seabird concentration areas in the eastern Baltic;

-Study community structure of inter-specific assemblages and ecological adaptations of wintering seabird populations;

-Study the processes of spatial dynamics and trends of spatial structure in regional seabird populations within the gradient of winter climatic conditions; and

-Study offshore migratory routes and temporary concentration areas of seabirds in the Baltic Proper.

[2020-10-01] The following invalid species names were corrected according to the Integrated Taxonomic Information System (ITIS).
Larus ridibundus (176835) => Chroicocephalus ridibundus (824041)
Corvus monedula (179746) => Coloeus monedula (916629)
Little Gull: Larus minutus (176840) => Hydrocoloeus minutus (824065)
Little Tern: Sterna albifrons (176899) => Sternula albifrons (824126)
Mergus albellus (175190) => Mergellus albellus (175196)

[2015-03-24] There were 199 records with a value of "EMPTY" or "empty" in the species column. These records are removed.

Overview

Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downloadable online. Other attributes may be obtained upon provider's permission.

Attributes in dataset

Attribute (table column)	Description
transect	Transect code
date	Date of observation
time	Time of observation
type	Transect type (1, 2, 3)
vessel	Ship name
o1	Observer name first letters (left)
o2	Observer name first letters (right)
status	definition not provided
lat	Latitude of observation
lon	Longitude of observation
knots	Ship speed (knots)
course	Ship course (degrees)
species	Species observed
tsn	Taxonomic Serial Number by ITIS
scientific	Scientific name
common	Common name
rank	Taxonomic rank
number	Number of animals observed
distance	Band of the transect (1, 2, 3 – inside, 4 - outside)
pattern	1 – fly, 2 – sit on the water, 3 – follow the ship
age	Age category of the bird (code)
plumage	Plumage (0, 1, 2, 3)
direction	Flight direction – degrees estimated as if the ship is heading to the North (360 degrees)
fd_real	Real flight direction (corrected according to ship
moult	Moulting status (0, 1, 2)
remarks	Remarks
geom	Geometry field added by OBIS-SEAMAP
oid	Unique ID number (generated by OBIS-SEAMAP)