It is rare for me to have two papers come out in two weeks and much more rare that they have so contrasting scales of extent. One of them deals with changes in 1500+ species of moths and beetles on the rooftop of the Natural History Museum of Denmark with the data collected by no more than two people at any point in time. The other deals with changes in abundance of merely 50 European breeding bird species but spans 18 countries and has data collected by a rough estimate of 50.000 birdwatchers.
One thing the two studies do have in common is their 20 year time scale. Both looked at changes from during the 1990's and the first decade of the 21st century.
Another shared characteristic are two general conclusions. (1) One supporting the notion hat specialist species in one or the other way are more sensitive to environmental change. (2) The other adding to the many studies showing that occurrences and abundances of species are shifting north with increasing temperatures.
Besides these shared insights many conclusions can better be summarized separately, so here are two short summaries:
The rooftop view
The main aim of the study was to investigate the changes in community composition, abundance and phenology across the 1500+ species of moths and beetles in relation to temperature and dietary specialization.
1. The community temperature index increased for both dietary specialized moths and beetles and not for the generalists during the period of warming.
2. Specialist were the only group that showed a net loss of cold-adapted and a net gain of warm-adapted species going from the 1990's to the 2000's.
3. Abundances of cold-adapted moths declined while it increased for warm adapted moths between the two decades.
4. Cold- and warm-adapted species exhibited divergent phenological changes such that the phenology of the leading edge of the abundance distribution advanced for cold-adapted species and the lagging edge of the abundance distribution was delayed for warm-adapted species .
5. Advances in phenology for cold-adapted species were larger than delays for warm-adapted species.
6. Specialist cold-adapted species showed the largest advancement in phenology.
The continent view
The main aim was to improve the empirical basis on which we attribute climate and land use change effects on wildlife populations by using both the short-term and long-term information available in large-scale census time series.
1. The seasonal manifestation of climate change is likely to affect the relative abundance of resident and migrant species.
2. Thus, populations belonging to three migratory strategies were influenced by changing weather conditions in three separate seasons of the year.
3. We found some of the first multi-year evidence at the annual time scale that warm-distributed species benefit more from warmer winters and early spring growing seasons than cold-distributed species.
4. On the decadal time scale, land use change may interact with climate change to cause larger declines of long-distance migrants in countries with more intensive agriculture.
5. Farmland specialist species have declined more than non-specialists over the past two decades, but it is hard to document the process behind these declines at the annual time scale.
I will leave it at that for now, and hope that these short summaries will at least be of some use and that the two studies will help us better understand and prepare for the coming biological consequences of ongoing climate change.
If nothing else, the two studies serve to show the value of both local and large-scale climate change studies.
PS: I am writing way too few posts than I would like at the moment. So here is a new self-imposed rule to get me writing - write a post on an impression every week. The posts should preferably be written in less time than it takes to watch an episode of Homeland or House of Cards - the faster the better. Now let's see if I can live up to those two goals.