The project

Our knowledge of ecology of migrants in their wintering grounds is extremely poor and severely hampers our ability to explain these declines and conserve this group of species. We lack even basic information about when birds arrive, the habitats they use and how they move around Africa.

The aim is to understand how Palearctic-African migrants use and move around the different vegetation zones found in West Africa, ranging from the semi-desert Sahelian region in Burkina Faso to the lush tropical rainforest in southern Ghana, and whether habitat change may impact them on their wintering grounds.

During the temperate winter of 2009/2010, using point count methodology and mist-netting, we recorded migrants along a degradation gradient at five different stations on a north-south transect. In 2010/2011 we plan to re-visit these sites as well as roving further afield to get a broader picture of migrant habitat use.

Saturday-Saturday 24th-31st March: The season ends, and the birds disperse?

The very last period of tracking of the season, and Rog and Japheth kept up with our wood warblers for much of the period. They did report however that the birds’ movements were becoming more erratic, seemingly roving over a wider area. Eventually, one by one from around the 28th to 30th the tags failed, or the birds disappeared – at this late stage we may never know which! Certainly there’s no time left available to cold-search for any colour-ringed birds. Roger tells me he felt that on the 31st, as they were finishing off some habitat surveys, they encountered far fewer wood warblers than we might have expected at the peak. Do fewer vocalisations mean they have just gone quiet, or have they genuinely moved on? Roger says he’s erring on the side of the latter!

Friday 23rd March: Landing in the UK

This morning I arrived back at Heathrow, and as regards the biological samples and all of that paperwork, in Accra no-one wanted to see anything, and in London, there wasn’t even anyone at the airport to declare anything to!

Meanwhile back in Ghana, Oppong has driven Japheth and Roger back to the study site to continue with tracking our three birds. The latest news is that the three birds have been tracked down once more – fabulous work guys!

Thursday 22nd March: Preparing to leave

Returned to Accra last night, and with my flight back to the UK this evening today has been the usual last-minute panic of making sure all lose ends are tied up – although this time I’m leaving Japheth and Roger to continue tracking until the 31st, as we think the tags will last until then. The main worry has been getting the paperwork sorted for the export from Ghana and then import to the UK of our biological samples (a few feathers etc). Japheth patiently spent hours at the Wildlife Division offices waiting for a simple signature on the export permit. Even 2 hrs before the airport check in, back at the hotel Roger and I were labelling the samples appropriately for transit, according to the terms of the import licence! Eventually job done, and I can now relax when I get to the airport!!

Monday-Wednesday 19th-21st March: My final days in the field

Much of this time spent in the “office” sadly! Japheth returned to Accra on the Monday and so Roger and Nick teamed up for the last few tracking sessions. I tried to make sense of all the tracking data so far, and catalogued as far as possible the rapidly growing library of canopy and leaf pictures. We hope at some stage to identify most of the commoner tree species either used by, or closely associated with the wood warblers (and indeed those species not being used that we record at the control habitat spots).

Saturday-Sunday 17th-18th March: The wood warblers grouping together

No tracking problems over the weekend, and exciting news is that at one point bird 7 and bird 3 were seen with bird 9, and even bird 10 was close to the same spot. It looks like the birds are coalescing a bit more, compared to their apparent solitary existence whilst moulting for much of the winter.

Friday 16th March: Finding the 3 new birds

Whilst Nick and I headed off to get stuck into some habitat mapping, Roger and Japheth set about tracking the 3 new birds. Unfortunately, Nick’s bird, number 8, proved very difficult. The signal was there but the bird seemed very mobile, so was not seen after early morning and mid-day attempts. Not such a problem with birds 9 and 10, and in fact a big bonus was spotting recently-lost bird 7 with bird 9. Perhaps even better still was that Roger and Japheth caught up with bird 5, for the first time since it was ringed on the 15th Jan!! A pretty good morning all told. In the evening Nick and I had a go looking for “his” bird #8, and we found it within about 10 minutes, teaching Japheth and Roger a lesson in tracking! (Just kidding guys! We got lucky, and the tag frequency had changed a bit).

Thursday 15th March: Some unexpected but welcome good fortune!

With just one bird left to track, and its traceable days numbered, and also nearing the end of the habitat mapping, it was beginning to look like we’d have to bring Roger’s flight forward substantially from the 12th April, as there’d be little possible fieldwork left for him to do! Well we needn’t have worried.

This morning, it was Japheth’s turn to decide where we should set the net for catching, and he and Roger put up two net’s on “bird 3 path”. Meanwhile Nick and I went after bird 7, but not a peep was heard from the bird’s tag. That was it then, the last of the tagged birds was off the radar. After over an hour of searching, a call came through from Roger – at last, they’d caught another wood warbler! Bird number 8 was due to be ringed by Nick, so we marched back in time to find the ringing station set up by Japheth. Nick was smiling from ear to ear as he processed “his” bird. With all measurements recorded, colour-rings added, and various samples taken, we attached the 6th radio tag of the season. With a predicted radio-tag life-span of 13 days, this bird will need to be tracked well after my 22nd March departure, and will give Roger some quality data to record once I’m gone!

Roger volunteered to take the wood warbler back to the area around the net where it had been caught, and to check the nets again. A few minutes later, and quite incredibly he returned with a second wood warbler. The London bus theory instantly sprang to mind – no wood warblers for weeks, then 2 come along at once.

This time Roger processed the bird, and chose the colours of Newcastle United FC for its colour-rings, black on the left, white on the right. Once done, I attached the tag with Nick’s help, whilst Roger and Japheth went to turn off the tapes and close the nets. Moments later they returned with a third wood warbler, and our 10th of the season. It was at this point that we really knew that the team would be very busy for the next couple of weeks (and confirmed the London bus thing too!!). An amazing morning, with 3 newly tagged wood warblers!! Another quick attempt to track bird 7, and another fail, but we’re not down-hearted with 3 birds to look forward to tracking tomorrow...

Monday-Wednesday 12th – 14th March: A missing radio-tag antenna

It seems that (thankfully) bird 7 is fairly settled, otherwise the faint signal would have made it tricky to find. It turns out that after the storm, for whatever reason, the antenna of the tag must have snapped off. Japheth noticed from a good close up view of the bird that the antenna wasn’t visible beyond the end of the tail. In the meantime, bird 6 is no longer traceable. After 15 full days the tag has finally failed over Sunday night, so on Monday morning there was no sign, even in its favoured tree.

A final full survey of the site on Monday was reasonably productive, although there weren’t quite the larger numbers of vocal and detectable individuals that I’d expected.

Monday- Sunday 5th – 11th March: The wood warblers start to sing

On their return from the field on Saturday, Roger and Japheth reported that during their trapping efforts the playback induced the first snippets of song from a couple of wood warblers, but unfortunately the birds just didn’t want to play ball, and avoided dropping close to the net. Whilst heading out to track bird 7 on the morning of the 6th, the first bird encountered was in fact bird 3, seen for the first time since 13th December, and in a small tree right next to where it was caught back on the 29th November.

Over the next few days we continued with the tracking of our two tagged birds and a short spell each morning with unsuccessful netting efforts. The rest of the time we embarked on the mammoth task of mapping the habitat of the study site, walking the boundaries of all fields and blocks of fallow, scrub and forest, and noted the alarming extent to which new fields were being cleared in readiness for the rainy season. Some of these plots are formerly-farmed fallow, but others have been untouched for years judging by the age of the trees being felled. We hope to discover the exact extent of newly-active farmland in relation to forest and wooded fallow when the habitat map is complete.

Tracking was rendered a little difficult on a couple of occasions due to a string of late afternoon downpours, with Nick, Japheth and Roger having to abandon one session in order to save the tracking equipment, and to avoid the obvious hazards of carrying a metal radio antenna in a thunderstorm. The guys got a good drenching but we otherwise fine! After some torrential rain on the evening of the 9th, we thought that bird 7’s tag had failed. On the morning of the 10th there was no signal from it from well within range of where the bird had been. Eventually a very faint “blip” in the headphones indicated that the tag was still active, but it transpired that we were directly below the bird. Somehow the signal had dropped right off, and we thought that the tag probably wouldn’t last much longer. However, the signal was clear enough for us to find it again twice that same day, and 3 times the next.

Sat 3rd March: From the "office"

Currently compiling all the data from the point-count transects done during the last few weeks, so that the team back in the UK can refine the presence-absence model. Also, am sifting through GPS data for last year’s tracked birds 1-3, as we need to revisit these spots to get the same habitat data as for the new birds. And we need to do it soon, as the villagers are starting to head to their farms en masse now that the first rains have arrived. Bit by bit, shrubby fallows are being cleared, and larger wood warbler-friendly trees are felled for timber, firewood and charcoal, and to create new arable spaces.

Having claimed since January (and I still do!) that the birds will be easier to entice to the net once they finish their moult and start vocalising, I recently started to doubt my memory of when the calling and singing started last spring. I thought last year we were hearing the first faint “pews” from around the 21st February, but this year as yet, the birds here (or indeed last week in the Volta region) have remained silent. A quick check of the data, and our records show that at every site where we saw wood warblers from the 23rd February, there were birds (though not all) calling or singing. Now almost 10 days later than that, the birds are still silent. Add to this the fact that we know some birds are still finishing moult, could it be that last year they finished sooner? Did they arrive on the final wintering grounds later this year than last? Certainly the numbers seen in the Sudan savannahs of Burkina well into October may hint that wetter than normal (and perhaps therefore more favourable?) conditions to the North could have held the birds for longer than last year. With no comparative arrival-date information, we can but guess for the moment. Next season we will have a better idea, but for now I remain confident that they will call and sing, and we will catch the 3 more that we have radio-tags for. Oh dear, famous last words!

Sat 25th Feb - Fri 2nd March: More resightings than ever

Our newly tagged bird has proved delightfully easy to find each time of asking. We started with two attempts per day on Saturday and Sunday (whilst of course continuing to try to catch more). It seemed to have settled in one of two trees, making refinding the next time quite simple, so from Monday we tried 3 tracking efforts. Still remaining easy to find, the bird did on 3 occasions during the week end up some 300m away, but each time on the next relocation it was back in its favourite patch. Very curious behaviour! Lots of data is being collected on the habitat choice when we do manage to find the bird, and also on some randomly selected patches where the bird isn’t being seen.

Meanwhile, Tuesday late morning, whilst Nick and I were walking towards bird 6 to track it for the second time that day, we spotted colour-ringed bird 4, some 350m from where it was caught and last seen, 83 days now known to be on site. A new record – for now!

Brilliant news on Wednesday morning, as the crew managed to catch a 7th bird. Roger had set the nets along “Bird 2 path” (an area frequently used by bird 2 last December), and within the hour witnessed the new bird throw itself at the net. This time yet to complete its tail moult, it nonetheless had new central feathers to which we could fix a tag. Japheth expertly carried out the process, and again the bird was soon transmitting its location from the treetops. It has since proved a little trickier to find than bird 6, but it has still been seen 6 times over Thursday and Friday. Not quite so tree-faithful, it is hanging around the zone where birds 2 and 3 from December overlapped their home-ranges. In fact, quite amazingly, on Thursday pm, it was easily relocated, but not before bird 2 was spotted in the same tree! This means that bird 2 has now been on site for 97 days, longer than many wood warblers remain in their breeding woodlands in Europe!!