With breeding season in full swing, I've been busy carrying out all the surveying to help us find out just what species are breeding here, how many of each there are, and how well they do at fledging young. So, how do we go about this?
First we need to decide which species to survey each year; these are all chosen in advance and set out in our five year Management Plan, and we tend to survey the priority species (ones which are declining nationally, or for which our reserve is particularly important) most often. It's not just birds though - we also have a timetable for surveying our priority butterflies, moths, mammals, fungi, spiders and plants too (although for some of these we need specialists to help us, as they can be a little tricky to identify reliably). Here at Conwy, we survey all our breeding waterbirds and water rail annually, and all the songbirds are monitored every five years.
The method we then use to work out how many of each are breeding depends on the species. The major conservation organisations got together years ago to decide on standardised methods for all the species so that (hopefully!) we all follow the same method, and can then share meaningful results. This also means that we can reliably compare results from year to year and make sure that we are seeing genuine increases or decreases in populations, not just changes in methods. For songbirds, we map where we hear males singing on dawn visits, and if we do this a number of times over the spring and summer, we can work out where the regular territories are, and how many of them we have on the reserve. With some birds, we end up with quite complicated maps!
Map of sedge warbler territories in 2012
Surveying waders, such as lapwing and oystercatcher, involves walking round the reserve once a week early in the morning between 1 April and 30 June and mapping all the nests I see with a telescope. At the end of the season, the total number of breeding birds for the reserve is calculated as the peak number of nests seen at any one time. We also follow the outcome of each brood of chicks to see whether they fledge (this is known as productivity), as the most important part is ensuring that the young survive to adulthood. With ducks, which nest deep in the reeds here, it's impossible to find the nests without causing disturbance, so we count the number of birds seen out on the water on each visit instead, and we can then convert these into number of pairs thought to have nested.
The trickiest of all to survey are the water rails - anyone who's spent hours patiently waiting to catch a glimpse of them knows just how elusive they can be. Not only is finding a nest practically impossible, just seeing the bird is unlikely! So instead we trick them into giving their presence away by playing them a recording of another water rail - if they're breeding, they respond indignantly to another "bird" invading their territory and call back, and we can then note that down as a breeding record. It's sneaky, but it works!
So at this time of year if you see me out and about armed with a CD player or a clipboard full of maps early in the morning, you'll know what I'm up to now....
As we move towards summer now, all our migrants have returned, but we still have plenty of birds passing through on their way further north. Up to 7 whimbrel and 6 wheatears have been seen daily, white wagtails are still moving through, the swifts returned on 1 May, there was a whinchat on 28 April, and a yellow wagtail on 29 April. There are plenty of goslings around too, and the first lapwing brood hatched on 3 May, always a joy to see.