Monday, 21 March 2011

Which are the most important breeding species in Lincs: Insights from BBS

The Breeding Bird Survey (BBS) is an annual survey which monitors changes in bird populations from year to year and trends over longer periods. It started in 1994 and took over from the Common Bird Census. Its big virtue is that it is based on randomly selected 1 km squares across all counties of the UK. It therefore provides a more accurate estimate of populations. The BBS is used for important conservation purposes such as determining red, amber or green conservation status. In 2009 volunteers surveyed a total of 3,243 squares across the UK of which 51 were in Lincolnshire.

All the data is available to anyone who wants to access it by country, region or county at this link:

There are 2 sets of data: first the number of squares each species has been recorded in, by year in each geographic area, second, the total numbers of each species counted by year in each geographic area. You can copy and paste the data into excel and analyse it as you wish.
So I've been messing about with the data to answer the question above. From the conservation point of view; which are the relatively most important species of conservation concern in Lincolnshire compared to the rest of the UK? I took the data and computed the rate of occurrence for all species I believe have bred or probably bred in Lincolnshire in the last 10 years and expressed that as a percentage of the rate of occurrence across the UK as a whole. Species occurring at a rate of 50%greater than the rest of the UK were designated as important in Lincolnshire. The conservation status (red or amber) of each species was noted from the RSPB Birds of Conservation Concern 2010 Report (available on their website).

Birds of conservation concern status is determined by the rate of fall of populations as measured by BBS and the atlas from the early 70s to 2009. So some relatively abundant birds like Skylark and House Sparrow are red because they are much less abundant than they used to be because of pressures arising from our industrial civilisation. Here is the list of species generated from this analysis.

The general UK trend of population change is also shown. It is possible that if we had a larger sample of BBS squares in Lincolnshire there could well be more rarer species on the list.
But the point is these birds are the jewels in our crown and we can make a better contribution to the overall UK conservation of these species by our efforts in Lincolnshire.
How can we do that. First by making sure that we record these species as confirmed breeders in as many squares as possible in the final season of the breeding atlas. Second by contributing to BBS and helping monitor annual changes in the populations of these birds. Third by supporting and lobbying for measures that contribute to the breeding success of these species through schemes like habitat management on Lincolnshire nature reserves and in the wider countryside, and the provision of nest boxes for those species which use them.
If you'd like take part in BBS which is primarily conducted in April and May have a look at and the more atlas roving records you can submit that confirm breeding for the above species, where they've not been confirmed so far, the better.
Look out for more posts about these individual species over the next few months.

Thursday, 10 March 2011

Some musings on "citizen science" and rarities

Reading Wikipedia today I discovered that the BTO is regarded as one of the worlds leading "citizen science" organisations. I was looking at definitions of birder, twitcher and ornithologist and it came as a surprise to me to find a new label. I started out as a science student so it feels good to be involved in massive projects like the atlas and BBS which have direct benefits for UK bird populations. Not sure about the citizen scientist description though; I prefer birder.

As it was a cold windy day I decided to do a bit of citizen science on my laptop. Two data sets available on the net have grabbed my attention recently. The first is the BBS data from Lincs available at showing how common breeding bird numbers have changed since 1990. Its fascinating. The second is the Birdguides Online UK Rarity archive of current defined BBRC rarities. Since the latter is only available by subscription I thought I would share it first. I copied and pasted all Lincs rarity records into a spreadsheet, sorted it by date order and then assigned every record from 1960 to 2008 to its 10 km square. For those interested a total of 251 records averaging about 5 a year, with a max of 14 in 1990 which was a Parrot Crossbill invasion year. I then mapped the results onto this 10km square schematic map of Lincs.

This produces lots of questions and as in stock markets past performance is not always a good guide for the future. For instance that 16 in the bottom right hand corner is Wisbech Sewage Farm which hasn't had a BBRC bird since 1983. Two squares above it with 4 is Frampton Marsh, shaping up to be one of our top hotspots. What are the chances of a Black Winged Pratincole there in 2011, what a hat trick that would be.

No one will be shocked that Gib is the best spot, though Donna Nook/Rimac run it close and the whole coast from Cleethorpes to Gib is good. I always wonder to what extent observer coverage, local weather variations, habitat, length of coast and funneling effects affect where birds are turned up. My dream is an experiment which would involve a series of days in which randomly selected 1 km squares on the coast and inland could be simultaneously covered in timed visits by a big team of observers to try and get a handle on why migrants turn up where they do. It would have to be repeated a number of times to generate sufficient data to get meaningful results. Perhaps there will be a chance to discuss the value/feasibility of this with BTO's professional scientists at our local conference at Riseholme on 16 April. If you haven't booked yet get a move on you don't want to miss out.
Finally where is the best place to live if you want to go for/find rarities in Lincs?
The picture left takes the data above and looking at each 10km square in Lincs shows the number of rarities accessible in a 5 x 5 grid centred on that square. The best place to live with a score of 139 is TF57. The village of Huttoft in that square is half way between Gib and Donna Nook and a couple of miles from the sea. Interestingly no BTO member or other serious birder lives in TF57 but George Rutter in Sloothby (TF47) is closest to the ideal position. Ed Mackrill in Welton le Marsh in TF46 is pretty close to it too, perhaps partly explaining why he has the biggest Lincs green list. Half of the Lincs top 10 listers live in just 2 squares TF38 and TF48 which are at the top of the triangle that runs from Louth to Theddlethorpe to Gunby Corner.
By the way if anyone would like the spreadsheet of the raw data (which runs from 1800) email me and I'll send you it.
I'll do the Lincs BBS data next time.