Long-term ecological studies have long since proved their value. They increase statistical power, provide context to shorter-term work, show the impact of rare events and contribute disproportionally to ecology and policy among other benefits. As an effort to ground shorter term studies and studies of individual migratory species better in the ecosystems in which they take place, we have been collecting a series of ecosystem indicators. These indicators will take on a life of their own as time goes by.
Changes in terrestrial bird populations
By carrying out point counts along roads across South Iceland in late June we are able to get a quick and efficient estimate of annual variation in breeding bird numbers. As most of our studies of individual species are carried out on fixed study sites, these general counts over larger areas help us to separate site-based local effects from the general condition of those populations. These surveys also help us to address the contribution of large-scale processes to the variation in distribution and abundance of Iceland's common landbirds.
Large-scale productivity of large waders
While carrying out point counts in June we count the number of broods of large waders (particularly Black-tailed Godwits, Whimbrels and Oystercatchers) along the transect and estimate chick size and brood size for the latter two species. As chicks of individual species have peak emergence at different times we repeat this count in late July. By using this simple approach we have shown how the productivity of Black-tailed Godwits is strongly linked to spring temperatures and how rare events (volcanic eruptions) can have a short term effect on producitvity.
Breeding phenology of waders
By finding nests of waders and applying standard flotation techniques to eggs we can estimate timing of laying for a range of common species. Timing of laying is a critical event in the annual cycle of birds, varies with migratory strategy within and between wader species and is very sensitive to weather. These measurements help us to better understand the links between phenology and demography and to assess the reproductive consequences of climate change across a range of migratory strategies.
Variation in food abundance
Common invertebrates form the stable food source for most waders. Temporal and spatial variation in food supplies is sensitive to weather and hence climate change and can have a pivotal effect on the demography of migratory waders in the future. To assess annual and temporal variation in food abundance we run window traps which collect flying invertebrates and these are emptied weekly . This variation can be explored in context with phenology of breeding and reproductive output across species.
Window trap for monitoring of variation in invertebrate abundance and timing of emergence.
Points where counts of breeding birds are carried out in June each year.