This report from Norwegian Ornithological Society (NOF) makes a summary of the current status for the Slavonian Grebe and is a suggestion for a National Action Plan (NAP) for the species in Norway. The report will constitute the technical basis for the Norwegian directorate for nature management (DN) when publishing a NAP for the species in Norway.
The Slavonian Grebe is listed as Endangered in the Norwegian Red List of Threatened species in 2006. In 2007, NOF accomplished a total survey of the breeding population of Slavonian Grebes in Norway that produced an estimate of 750‐850 pairs. The survey concluded that the species has increased both in numbers and geographical distribution during the last 20 years with the exception of some areas in the counties Nordland and Troms. I the areas with reported decrease, the magnitude of the decrease is, however, uncertain. Reported decrease in some areas do not necessarily reflect a real population decline, since the numbers of breeding Slavonian Grebes has increased in other areas in the same counties. The Slavonian Grebe quickly exploits new constructed
or restored habitats, and may abandon these after a few years in order to settle in other localities. If the focus on the population development is on a local scale, erroneous conclusions on population decline could easily be made, if new potential breeding localities is not surveyed simultaneously.
In Nord‐Trøndelag County the population numbers has been stable during the last 15 years, while the distribution area has increased. In all other counties with Slavonian Grebe populations, there has been an evident increase both in population numbers and distribution area during the last 10‐15 years. This situation especially applies for Finnmark, Sør‐Trøndelag, Hedmark, Oppland and Buskerud counties.
The classic breeding localities for the Slavonian Grebe in Norway are nutrient‐rich lowland lakes with seepage from cultivated land. In Oppland County, however, many pairs has established themselves in small ponds in peat bogs or forests without nutrient‐rich seepage from agricultural areas, and in Hedmark County, artificial ponds in the agricultural landscape has frequently been used as breeding ponds for the Slavonian Grebe. The population increase in this county is viewed as a direct response to the increased access to suitable breeding habitats. Slavonian Grebes are vulnerable to competition from fish, and a common denominator for the breeding lakes and ponds is often the absence of big fish.
The report suggests the following goal for the NAP: In the long term, the Slavonian Grebe should be distributed with a viable population within the natural distribution area of the species in Norway. The current population numbers estimated at 750‐850 breeding pairs should be kept at least at the same level in the future. In the short term the Slavonian Grebe should be managed as a vulnerable species with special considerations and actions in order to maintain the regional populations.
We further suggest the following aims for the NAP: * Establish an annual monitoring system from 2010 onwards, * map the factors that induce the Slavonian Grebes abandonment of certain lakes/ponds. *render important breeding lakes for Slavonian Grebes free from American Mink within 2014, * avoid introduction of fish into important or potentially important breeding lakes and remove introduced fish from some lakes in the period 2010‐2014,*establish and maintain a readiness for implementation of conservation actions when needed. Since the Slavonian Grebe apparently don’t have an unambiguous negative population development, it is difficult to be definite on what conservation actions to implement in a regional scale within the time frame of the NAP (5 years). One important action will be to establish an adequate monitoring system in order to follow the population development on an annual basis. We suggest that the breeding populations should be surveyed on an annual basis in the following monitoring areas: Porsanger, Finnmark County, Balsfjord/Storfjord, Troms County, Bø/Vestvågøy, Nordland County, Norsk Ornitologisk Forening – Rapport 5‐2009 6 Levanger/Stjørdal/Verdal, Nord‐Trøndelag County, Vardal/Snertingdalen/Biri, Oppland County. The next National total survey is suggested accomplished in 2014, seven years after NOF’s first total survey. Actions to remove fish are suggested in former good breeding lakes where it is probable that the Slavonian Grebe has disappeared due to introduction of fish. Furthermore, we suggest a reduction/removal of populations of American Mink in the breeding lakes where this species is recorded, especially in the areas where population decline of Slavonian Grebes has been reported. Net fishing in spring may be a significant mortality factor for Slavonian Grebes that get stuck in the nets and drowns while diving. In order to reduce this mortality factor, public awareness campaigns may help, but in some lakes we suggest a ban on net fishing in spring. An efficient way of creating new breeding habitats for the Slavonian Grebe is to establish artificial ponds in farmland areas. This is suggested as a management action in areas with suspected decrease because former breeding lakes have become unsuitable.
Human disturbance may cause the Slavonian Grebe to abandon the nest, or it may result in the eggs being exposed to egg predators. One significant source for repeated human disturbance is recreational activities in the lakes, and it is specially those lakes situated close to aggregation of cottages that are exposed to intense recreational activities.
It is unknown where the Norwegian Slavonian Grebes are wintering, and it is therefore important to map particularly sensitive areas for the species in relation to oil spill. The report suggests mapping where the Norwegian breeding birds are wintering, through a satellite telemetry project. In addition, other research activities are suggested, like mapping of basic parameters as nutrient availability, clutch size etc.
We suggest that office of the County Governor of Troms is delegated the responsibility of
implementing the NAP, and that NOF, who accomplished the first National mapping of Slavonian Grebes in 2007 is responsible for the annual monitoring and future National surveys. The NAP is suggested to be implemented from 2010 onwards, and should be subject for evaluation after the second National survey is accomplished in 2014. The annual budget in the period 2010‐2014 is considered to be approx. 560 000 in the first 4 years, and somewhat higher the last year because of the National survey this year. The internet portal Artsobservasjoner www.artsobservasjoner.no should be used for storing and methodical treatment of the monitoring data for Slavonian Grebes.