The COAT field season is well underway, and several fieldworks have already been completed. Here is a brief report from some of them that took place in Finnmark.
A COAT fieldworker checking a small mamal camera trap. Photo: Eeva Soininen
Tundra-forest module
The module completed its counts of moth larvae in Troms and Varanger during the first week of July. The data from Troms shows that populations of both autumnal moth, winter moth and scarce umber moth in this region have increased from last year. The counts for this year are mostly dominated by the winter moth, which has locally become abundant enough to cause severe defoliation of birch forest. However, there is also large spatial heterogeneity in winter moth densities, with some monitoring sites in Troms having very low larval counts.
The larval counts from Varanger resemble those of 2023, in the sense that they show very low densities of both autumnal moth and winter moth across all monitoring sites (scarce umber moth is so far absent from this region).
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Automnal moths. Photo: Moritz Klinghardt
Ptarmigan module
This year we have tested a new type of camera trap to monitor nest predation on ground nesting birds. We tried out a time laps camera with a wide-angle lens, which can be placed on the ground 0.5m from the nest. For the test we used artificial nests with quail eggs. The results are promising and will be formally evaluated in a master thesis. We also got help from experts from NMBU and Oslo University Museum to search for real nests of waders, ptarmigans, Lapland bunting and meadow pipits, so that we from next year hopefully can apply the camera traps on real nests.
A COAT fieldworker installing a nest predation camera trap. Photo: Eivind Flittie Kleiven
Small rodent module
In early July, we checked all small mammal camera traps at Komagdalen and Vestre Jakobselv study areas. This year, we saw a lot of mustelids, and several cameras had photographed entire families! (See below) It seems like the rodent populations had crashed during winter in a spatially heterogenous way. That means that in some areas, there were only very few photos of rodents during the spring – and correspondingly we observed no nesting birds of prey and only little waders. In other areas rodents were still abundant during the early summer, and nesting long-tailed skuas were abundant. We also registered lemming activity and shrub presence in snowbeds and can report that in some snowbeds lemmings had really plowed through everything last winter – except the exclosures that are meant to keep them out. So, we can really expect a contrast between the lemming-impacted control plots and the lemmings-free plots.
A entire family of stouts photogrphed in one of our camera traps. Photo: COAT