The Kenya Bird Map has been running for around three years and we are getting some really interesting early results from it now. Because of its neatly tight protocol that is simple to follow (and with the excellent smartphone app, BirdLasser, that makes it easier still), the data generated are wonderfully analysable with relative ease (you don't need a super-computer!).

We've generated some plots of the phenology (seasonality / change over time) of some species of interest and I thought to share a few with you here in the hope that it will stimulate further interest in both contributing records to the atlas (the more data, the better the results and more useful for bird conservation in Kenya) and in using the data (it is open source, freely available to all with the purpose of benefiting research and conservation).

The following graphs show the reporting rate of a species across the year. I'll try and explain it a little! Along the Y-axis of the graph (the vertical line) we have 'reporting rate' - i.e. the percentage of all Full Protocol cards submitted which had the species in question reported on them. The X-axis (horizontal along the bottom) shows the progression of time through the year by 'pentade' - confusingly similar but not to be confused with a 'pentad'. A pentade (pronounced 'pent-aid') is a period of FIVE DAYS (in the same way that a week is a period of 7 days). A pentad is the atlas square measuring 5 x 5 minutes. There are 73 pentades in a year because 365/5=73. The first pentade on this graph runs from 1 to 5 January, the second from 6 to 10 January etc. no 73 is 27-31 December - and there are therefore about six pentades per month.

Each 'X' on the plot represents the reporting rate in each pentade. The red line is the smoothed average reporting rate through the year. The smoothed line is not a formal model, it is simply designed to lead the eye through the data - but it is a sophisticated smoother (thanks to Les Underhill who in fact produced these plots for us).

Starting with a common species which gives an idea just how the data will show what would be an expected pattern - the Common Bulbul, a common resident. Here, the reporting rate is high (65-70% of cards have the bulbul reported on them) and is consistent throughout the year - i.e. it is resident, numbers don't fluctuate - just as you would have thought!

A similar pattern is shown by the Woodland Kingfisher - but here the reporting rate is much lower (2-3%) as it is a far less common species than the bulbul:

Looking at well-known migrants, here is a not very surprising overall pattern for a common Palearctic species, the Willow Warbler, but with some very sweet detail within it:

What this immediately tells us is that this is a migrant that during the middle part of the year (June-Sept) it is entirely absent from Kenya, that there is a rapid arrival in Oct to late November with a slight peak in numbers in early December. During the heart of the northern winter, Willow Warblers are not too hard to find (c.20% reporting rate) but there is a clear arrival from the second half of February, presumably of migrants from the south, when they then become definitely more common in the northward migration in March / early April before a rapid departure with all gone by the end of May (and the steepness of the slope tells us the departure is more rapid than the arrival in October - i.e. the birds disappear in a shorter period than they arrive).

These are awesome results showing in hard figures that Willow Warblers are most numerous during the northward migration - something any of us who've done any serious brrding in Kenya will know... but to have hard data showing it is superb. This suggests that on their way south a number must either overfly Kenya without stopping or migrate farther west - as is known to happen strongly in other species such as Red-backed Shrike. An area for more study...

Another really interesting pattern of a migrant, this time an Afrotropical species, is for the Red-capped Robin Chat:

This is the opposite pattern to the Willow Warbler as it migrates south to breed during our summer - December-March - when you can see it is absent. One or two start to appear in March but there is a rapid arrival in May and apparently a second arrival in July - or, given it comes to a sharp peak towards the end of August, this would appear as a passage of birds since the reporting rate then drops off steadily through to the end of the year. An awesome picture of this species' seasonality, no? It raises interesting questions for further research - e.g. if there is a passage of birds, where are they on passage from?

Some may know that there are, in fact, resident populations of Red-capped Robin Chat as well, mostly inland - which has not been picked up by the data. This is because they are far commoner on the coast where they are a clear migrant and so these are the ones that have been reported so far. For the inland resident populations you have to go looking hard to find the species and so we need more observations, more records to show this - i.e. more birders out there joining in on what is definitely going to be the key bird conservation project of the next 10 to 20 years for Kenya.

These results have been produced from what are actually relatively very small amounts of data - which shows the huge strength of the bird atlas protocol - simple, yet tight, producing very analysable data. The protocol is simply: within a single atlas square, min of 2 hours focussed birding over a five day period (a pentade...) and record all species in the order you encounter them noting the total seen after each hour of birding.

The potential for digging out a wide range of extremely relevant and important patterns for bird conservation is enormous - with sufficient data you can produce the same plots as above but annually to see any changes in migration pattern over time (possibly caused by climate change, for e.g.); species that are under threat - e.g. vultures - will show over time an overall decrease in reporting rate, proving beyond doubt that there IS a problem..., when government takes action and they start to recover (here's hoping!), then the atlas data will pick this up and show it.

These plots are taking data from the whole of Kenya - with sufficient data, you can do the same analysis for a given area (e.g. a ranch, a conservation area), even just a single pentad and see local patterns of phenology (e.g. dry season movements).

The possibilities go on and on. If you are at all interested in birds and their conservation in Kenya, please do join us in this exciting project. The protocol is simple and actually a heck of a lot of fun to do, it hones your birding skills even further and gets to be quite addictive (perhaps there should be a warning put on it?!).

Write to Sidney at kenyabirdmap@naturekenya.org to register or for more information.

And THANK you to all those who have contributed so far for being a part of this awesome project!

Colin

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Colin Jackson
A Rocha Kenya
Kenya Bird Map Management Team

Cell: 
+254 (0)722 842366
      
http://www.arocha.org
http://www.assets-kenya.org
http://kenyabirdmap.adu.org.za