Most of the activites at the station focuses on population monitoring of migrating and breeding birds. Amongst the projects are:
This diagram shows the number of Garden Warbler observed pr. year from 1969 - 2005. In our database we have almost half a millon observations. Due to low activity in the years from 1969 - 1981, we see lower numbers in these years.
Ringing in the constant effort scheme
The majority of birds ringed at the station are caught in the constant effort scheme. Standardized methods are designated for monitoring migrating passerines. This takes place near the northern end of the island, where the shrub vegetation is low and narrow. Here the conditions are ideal for cathcing several species of passerines, passing by both in spring and autumn.
(Example below: Blackcap, Sylvia Atricapilla. Ringed birds in the autumn from 1990)
10 mist nets are in use every day in the migration periods: 15.04.-15.06. and 15.07.-31.10. The nets are open from sunrise and at least 5 hours onwards. The nets are closed when the migration has stopped, at least before 13.00. By unfavourable weather (wind, precipitation etc) the nets are not in use.
The constant effort scheme was started in 1990. Such larger data sets are useful as strong indicators of population changes in migrating birds. In some species significant changes can be detected. Interestingly, the results from Jomfruland show the same patterns as the data from other nordic bird observatories in some species.
Ringing - recoveries and controls
Approximately 7.000-12.000 birds are caught at the station every year. Some of these are allready ringed at other localities in Norway or abroad. Along with reported recoveries of our own birds, these data can be used for mapping of bird movements of the different species.
In this way both migration routes, breeding areas and wintering areas can be detected for those birds passing by Jomfruland or breeding on the island. This information is important, for example in letting us know which populations are being monitored in the constant effort scheme.
Observations of migrating birds
After 35 years of activity at the bird observatory, there has been gathered a vaste data set of observations. Most of the data set has been gathered by non-standardized methods. Nonetheless, these data can tell a lot about the development in occurrence for several species in this time interval.
This diagram shows the number of Tree Pipits observed pr. year from 1969 - 2005. In our database we have almost half a millon observations. Due to low activity in the years from 1969 - 1981, we see lower numbers in these years.
Waterbird census in winter 
The waters surrounding Jomfruland are important resting and feeding grounds for several species of waterfowl, such as divers, grebes, cormorants, ducks and auks. This is especially the case during winter and migration periodes. The observatory is conducting standardized countings of waterbirds during the winter season. .
The countings was started in the 1998-99 season. Thus the data set is still too small to give clear indications of changes in occurrence.
Monitoring of breeding sea birds
Several islets along the coast of Telemark are protected as seabird breeding reserves. Every year the populations of breeding birds are censused by standardized methods. This is providing clear indications of populatios changes in several species. The project has been runnings since 1974.
(Example below: Mew gull, Larus canus. Breeding population, pairs, in the reserves.)
