Beijing Swift project preliminary results

Action for Swifts is delighted to have been involved in the Beijing Swift project where we attached 31 geolocators to Swifts at the Summer Palace in 2014 (see story). On 24th May 2015 we retrapped 13 of these birds, and downloaded all of the data successfully.

by Dick

Prior to this project, the journey made by these iconic birds - synonymous with Beijing since 1417 when they made their nests in the original city gatehouses, was a matter of speculation. We now know that they arrive in Beijing in April and, after breeding, begin their long journey to Africa in late July, taking a route that first leads them west-northwest into Mongolia, from where they pass north of the Tianshan mountains, then south through Iran and central Arabia into tropical Africa, before spending 3 months of the winter in Namibia and the Western Cape.

They begin the return journey in February, retracing a similar route on the way back, arriving in Beijing in mid-April, a journey that sees them cross about 20 borders. 

For the full story, read the Press release

Also see piece on Birding Beijing
The Guardian
Xinhua article - largest media agency in China
Birdguides webzine
British Birds
Birding Frontiers

One track of 13 geolocators recovered (click map to enlarge)

Lyndon Kearsley releasing a Swift with geolocator Photo Zhang Weimin

Terry Townshend, right, releasing a Swift Photo Zhang Weimin

#beijing

Is 2014 really a good year?

There seems to be a general impression that this is a good year for Swifts in the UK, however, the Reporting Rate recorded by BirdTrack across the UK shows 2014 to be lower than 2013 and 2012, indeed, it seems to be the lowest ever! [Reporting Rate is the percentage of BirdTrack lists that record at least 1 Swift].

Written by Dick

BirdTrack Reporting Rate for Swifts, 2006-2008
(click on graphs to see them larger)

BirdTrack Reporting Rate for Swifts, 2012-2014

(click on graphs to see them larger)

Athough not designed for this purpose, an advantage of BirdTrack for an early indication of trends is that the data is available up to 2 years ahead of BBS. In fact it is available in near realtime!

The graphs, left, include the Reporting Rates for 2006 and for 2014.

The BirdTrack Reporting Rate for 2006 through June to mid-July (the peak season) averages 47.2%. In 2014, the reporting rate for this period averages 37.6%.

This is a decline in reporting rate of 20% in 8 years. Given that changes in BirdTrack Reporting Rate underestimate changes in abundance, this is quite a drop.

[Older graphs than this on the BTO website were calculated incorrectly - so we cannot go back further than 2006]

There could be a number of explanations for the apparent contradiction between numbers at colonies and numbers recorded by BirdTrack:

With the fine weather, it could mean that Swifts are finding plenty of food near their colonies, giving colony watchers an impression of abundance, but, as Swifts do not need to forage further afield, maybe they are seen less frequently by BirdTrack listers.

It could just be that they fly higher in good weather, so are again less likely to be seen.

Alternatively, it could be that those birds that still have their nesting places intact have had a good year, but there may be fewer intact nesting places, so birds recorded away from colonies may appear scarcer.

Another explanation is that birds from destroyed colonies are prospecting those colonies that still exist. This ties in with anecdotes from Poland, where survey data indicates increasing Swift numbers at a time when large numbers of colonies are being lost - the birds may be in the air, and visible, rather than sitting on their nests.

Whatever the explanation, it is a situation that needs watching.

Bird Atlas 2007-11: what does it say about Swifts?

The preface to this monumental work says that this book will set the agenda for bird conservation for the next 20 years. We are therefore interested to see what it says about Swifts, in particular what has happened since the previous Atlases in 1968-72 and 1988-91?
Perhaps the most important takeway is that Swifts have been declining for at least 40 years, something not brought out in more recent datasets.

Click maps to enlarge

The Breeding Distribution Map shows all those 10km squares in which at least 1 pair of Swifts was found possibly, probably or proved breeding. Swifts breed in virtually every square apart from north and west Scotland, and the western part of Ireland. 

If one compared it with the equivalent map for 1988-91, it would appear similar because relatively few squares have completely lost, or gained Swifts in the intervening years. However, the two maps below reveal more clearly what has actually been going on.


 

The Breeding Relative Abundance Change Map gives a graphical representation in the change in occupied tetrads in each 20km square between the two Atlases. Red signifies an increase, blue a decrease: the darker the colour the bigger the change.

This map shows that rather more squares decreased in this measure than increased. 

Though the overall pattern is one of decline, there are some areas of good news, including southern Ireland in a country where overall there have been the most decreases.

The Breeding Distribution Change Map highlights those 10km squares that have completely lost or gained breeding Swifts since the previous two Atlases in 1968-72 and 1988-91. A black triangle means a loss, a red triangle means a gain. A small triangle signifies the change since 1968-72 and a large triangle since 1988-91. 

There are far more losses than gains. It is clear that Swifts have been losing ground for at least the last 40 years, As one might expect, the losses are concentrated in those areas where Swifts are more sparsely distributed, particularly Ireland, parts of Wales and north and western Scotland. 

A low density population is more likely to disappear than a higher one. It is on the edges of a species distribution where change is most obvious. 

So the Atlas is telling the same story as the Breeding Bird Census and the trends in BirdTrack reporting rates. It is helpful that there is no ambiguity in the trends determined by these three BTO datasets, it means conservation decisions can be made with there being little doubt about what the data is telling us.

You can read more about the Atlas, with an excellent promotional video here

Acknowledgements
Thank you to Dawn Balmer and the BTO for permission to publish these maps.

Reference
Balmer, D.E., Gillings, S., Caffrey, B. J., Swann, R. L., Downie, I. S. & Fuller, R. J. 2013. Bird Atlas 2007-11: The breeding and wintering birds of Britain and Ireland. BTO Books, Thetford.

BTO Breeding Bird Survey Report 2012

The BTO/JNCC/RSPB BBS report for 2012 is now published; you can download and read it here. 

by Dick

It is a good read representing the results from 3,430 randomly allocated 1km squares. Each square is surveyed twice, the early surveys, in April to mid May, are likely to record fewer Swifts than the later ones in mid May to late June when the Swift population is at its peak.

Unlike song birds, Swifts recorded in a 1km square, out in the country, are unlikely to be breeding in that square. Indeed, they are almost as likely to be non-breeders as breeders, but one hopes that the frequency of occurrence of Swifts during BBS surveys is a good proxy for the general population level. For Swifts it is more a total population level index than a breeding bird index.

BBS Index for Swift, UK, 1994 - 2012
Index values are scaled so that the smoothed index in 1995 is 100

The results presented for Swift for the whole UK record a decline of 39% between 1995 and 2011, then an increase of 20% between 2011 and 2012.

So the 2011 UK population is estimated at 61% of the 1995 population. Note that this is calculated from the values behind the smoothed red trend line. The years 1994 and 2012 are not used as the smoothed values at the extremes are not considered reliable. Thus we have scaled the graphs so the smoothed index value in 1995 is set to 100.

Although the 2012 annual index is 120% of the 2011 one, it would not be appropriate to multiply the 2011 smoothed value by 120%, as the 120% figure comes from the annual index values

See BBS 2012 report for confidence limits

The numbers are also presented for 3 of the 4 UK countries, there was not enough data for Northern Ireland.

However, all of the numbers in this table have wide confidence limits, so we will have to wait for 2013 and beyond for smoothed index values in 2012.

It is tempting to speculate that the long wet summer of 2012 forced Swifts out into the countryside to feed in areas where there were BBS survey squares. However, this does not explain the situation in Scotland.

Thank you Kate Risely, BBS National Organiser, for providing the data for the graphs.

Nest Recording of Swifts in Boxes with Cameras

The increasing number of people with cameras in Swift nest boxes provides a great opportunity to obtain high quality nest records for the BTO. This could help to reverse the decline in numbers of Nest Record Cards for Swift in recent years

Written by Jake & Dick

The BTO's Nest Record Scheme provides important information about changes in populations over time, based on such factors as average egg laying date, clutch size, incubation and fledging period, and hatching and fledging success rates.

Nest record cards for Swift recorded each year
showing the recent decline (click graph to enlarge)

3 chicks with large primary feathers
(can you spot the 3rd one?)

We know there is an ongoing decline in the population of Swifts in this country, so it is important to collect data on breeding success rates, but no more than a hundred nest records are received each year, and this number has halved since 2010.

Historic data would be extremely valuable in helping to combat the dearth of records in recent years.

Moreover, the information on the cards is generally minimal, possibly no more than the record from a single visit.

Even with multiple visits, The BTO has to make intelligent inferences to determine egg laying, hatching and fledging dates. With cameras in boxes, there is the potential to determine the timing precisely of all of these events without any guesswork.

Example nest record card

Nest recording is not an arduous task, though the more you record, the better. The optimum would be to produce a series of up to 10 dated observations detailing the first sighting of an egg in the nest, the maximum clutch size and when it was first observed, the date of first hatching, the number of chicks present at approximately weekly intervals, together with their stage of development, and the timing of any failures or successful fledging.

In the (real) example shown here, we knew everything from the date the parents arrived, when the eggs were laid, when the eggs hatched, when the chicks fledged, and finally when the parent left for Africa. In this case, one parent went missing on 4th July. [The parent that survived carried a geolocator to Africa in 2011 and has returned since then.]

Note that although the instructions say that further visits should be included on continuation cards, the BTO nest record software cannot deal with more than 10 visits, meaning that all of the most essential information should be squeezed onto the first card.

In this example, we have inserted the last time there were 2 eggs, just before there was 1 chick This helps the BTO's algorithms to pin down the hatching date exactly. Because of the 10 visit restriction, we have not recorded the dates that the parents arrived on the card.

If you know that you will be unable to watch the camera for a period, record the last state of play, including nest contents, primary feather length etc. as well as the position on your return. See this pdf link, also referenced below, for how to describe chicks.

Anyone who would like to contribute can get in touch with the BTO at nrs@bto.org to register as a nest recorder and receive the necessary instructions and blank cards. It is essential that the data is submitted on these cards, as the BTO cannot handle any other format.
[ we understand that there will eventually be a web-based system]

If you already have such information recorded from previous seasons, it is an easy matter to transfer it to Nest Record Cards using the standard BTO codings.

For a fuller description of how to record Swift nest records download this pdf, written by Vince Lea.

We thank Dave Leech, BTO Senior Research Ecologist NRS, CES & RAS, for suggested improvements to this post.

BTO url: http://www.bto.org/volunteer-surveys/nrs/taking-part

Hourly pattern of Swift activity

Contributed by Dick

Here in Landbeach, I have CCTV cameras watching the outside of all 19 of my Swift boxes, so that I can monitor every entry and exit in every box. I also have 2 cameras in boxes.

It is not without its problems, the motion detection sometimes misses events, spiders spinning their webs across the lenses cause much redundant footage, as do shadows dancing around on the boxes from the nearby trees. I have not time to trawl through hours of dancing shadows to see arriving or departing Swifts.

This is not to mention some mysterious creature that occasionally yanks one of the cameras so that it is pointing completely in the wrong direction.

However, I think the data I have gathered is good enough to give a reasonable idea of the pattern of activity throughout the day.

The purpose of this post is to give people monitoring colonies some idea of the best times to stand watching nest sites to see if they are occupied.

Of course on any particular day, the pattern will be affected by local weather conditions. On cold wet days, the birds will venture out later and will arrive back earlier

I will try to keep this chart up to date so that folk can check it out before venturing out to monitor breeding Swifts.

The winter movements of a pair of Swifts (part 3)

Contributed by Lyndon Kearsley

Getting into position. A further look at the winter timing of a pair of Belgian swifts in 2012. This is the third instalment of our story about where the Swifts were in December and February.

March is a difficult month for tracking birds using light level dataloggers. From about 15 days either side of the spring equinox on the 20th, the day length is about the same across all latitudes and so no north / south fix is possible. However the timing of local midday is not affected, so longitude (how far east or west) can be calculated. 

In the following map I've plotted the locations during March (shown in closed or open black dots) by using the longitude combined with a fabricated latitude derived by simply dividing the first and last fix before and after the equinox by the number of days. The February and April positions are also included to show how this ties in before and after the equinox

You can see that the female leaves East Africa crossing rapidly to a position which coincides with her December location on the lower Congo River. She remained there at about that longitude for the last two weeks of the month and then departed towards West Africa at the beginning of April.

The male moved very little in this period probably remaining above the lower Congo River wetlands in the Democratic Republic of Congo.

                   Red dots are female positions in February and in April

                   Black dots are female positions in March

                   Blue dots are male positions in February and in April

                   Open dots are male positions in March
                  [Click map to enlarge]

The April tracks show how this story continues and marries up with this theory. The male indeed remains in the lower Congo until about the 20th of April when he too makes his move out to West Africa (Sierra Leone).

The female had already been in West Africa for quite a while by that time having crossed the Gulf of Guinea in early April, and her positions show her to have been first in Ivory coast, then Liberia, Sierra Leone and Guinea. Bear in mind that geolocator fixes are at best approximate and the tracks shown are smoothed 3 day rolling averages. Never the less at this scale one gets a clear idea of the birds timing and strategy.

On 29th and 30th April both birds are shown to be somewhere in Sierra Leone and closer to each other than they have been all winter, nicely placed for the dash back to Belgium.

Recently a  paper discussing a statistical track estimation solution for the latitude problem during both equinoxes was published by Wahlstrom et al (2012). 

Wahlstrom, N., Gustafsson, F., & Akesson, S. (2012, July). A voyage to Africa by Mr Swift. In Information Fusion (FUSION), 2012 15th International Conference on (pp. 808-815). IEEE.

How many Swifts are there in GB and the UK?

The February 2013 issue of British Birds has a paper titled 'Population estimates of Birds in Great Britain and the United Kingdom' by Andy Musgrove et al. This of course includes estimates for the Swift population. As Swift is such a famously difficult species to census, we thought it worthwhile taking a closer look, as well as coming up with our own "fag-packet" estimate to see how it compares.

Written by Dick

The population estimates are produced by the Avian Population Estimates Panel (APEP), composed of representatives from the BTO, GWCT, RSPB, WWT and JNCC. Their estimate of the population of the Common Swift in 2009 is:

GB: 87,000 pairs (63,000 - 111,000)

UK: 87,000 pairs (64,000 - 111,000)

[Note the UK includes the island of Great Britain and Northern Ireland].

The authors believe this to be an underestimate and that the reliability of the result is 'poor'.

The numbers are rounded to 2 digits (so the nearest 1000), implying that there are less than 1000 pairs in Northern Ireland. This seems low, given, for example, the huge numbers of Swifts sometimes seen feeding over Lough Neagh.

The estimate is based on the results of the Breeding Bird Survey (BBS), a survey designed for monitoring population change, rather than absolute population levels. The method calculates the density of birds within a defined distance of a transect, and then extrapolates across the country.

It is not stated whether account has been made for non-breeders and incubating breeders. Swifts do not breed until about 4 years old, implying that roughly 40% must be non breeders. If haIf the breeders are occupied in a nest site, then only ~70% will be at large at any one time for BBS participants to see them.

The final paragraph of the paper invites people to get involved in gathering data and coming up with their own ideas, so here goes!

Fag-packet estimate

Swifts nest in houses, so one might expect the number of pairs in any area to be proportional to the number of houses. In what follows, we do not always know how many houses there are, but we have found figures for the human population, so we have divided this by 2.5 to get the number of houses. From this we calculate the number of pairs per 1000 houses, then we can extrapolate across the UK.

There are a number of published local estimates of the breeding Swift population (see table below). One of the earlier ones was Perrins estimate in 1971 who thought that there were between  20 and 50 times as many breeding Swifts in Oxford as there were in the museum tower, which numbered 40 pairs at the time. So we have taken his lowest number, 800 pairs in 1971. Likewise for Northants we have used a minimum estimate for the population in 1998 by taking the minimum from the 1978 survey times the maximum percentage decline estimated in 1998 (Richardson 1978 and 1998).

Since 1994, Swifts have been declining at a rate of about 3% per annum (BBS).  So, to estimate the population in 2009, we need to make an adjustment to account for the decline since the survey was made. As there are no figures before BBS, we have used the same rate of decline to adjust numbers obtained before 1994 (i.e. Oxford).

The number of households in the UK is ~25 million in 2009. So, the APEP estimate of 87,000 pairs in 2009 translates into 3.5 pairs of Swifts per 1000 houses. In the table below, most surveys come up with a density larger than this:

Analysis of some Swift survey data.

The minimum (Northants) and maximum (Oxford villages) densities translate into overall breeding population estimates between 78,000 and 265,000 pairs. Note though that the Oxford villages sample size is small.

To calculate an estimated mean density across the UK, we can use either a calculated overall mean sample density, or the mean of the sample densities.

Mean sample density - total pairs / total households:
Total estimated pairs in 2009: 6,580
Total Households: 958,252
Average pairs per 1000 households: 6.87
UK population (25,000,000 households): 171,671 pairs

Mean of sample densities: 
Average of sample densities: 6.28 pairs per 1000 households. 
UK population (25,000,000 households): 156,894 pairs

The first estimate is effectively weighted by sample size and the second is unweighted. The difference is because the largest sample (Cheshire) recorded a relatively high density. 

Based on this latter, lower figure, the estimate for Northern Ireland, with 1.8 million people, would come out at about 4,700 breeding pairs, but we did not use any data from Northern Ireland!

So how many Swifts are there in the UK in total?

Using our lower figure, rounded to 2 figures, of 160,000 as an estimate of UK breeding pairs in 2009, and given that  ~40% are non breeders, then the total number of individual Swifts in the UK during the breeding season in 2009 may have been of the order of 530,000. If each pair of Swifts yields on average 1.5 young, then the number of Swifts leaving the UK in the autumn is 770,000 (minus a small amount of mortality during the breeding season).

Comparison with some other urban species

The paper includes an estimate for House Sparrow of 5,300,000 pairs in the UK, and for Starling the number is 1,900,000 pairs. It is ironic that these two hole-nesting species are red-listed, but Swift, at an official estimate of 87,000, is only amber listed. There must be scope for a huge increase in the Swift population in the UK if we could provide nesting sites for them.

Conclusion

This analysis is a fag packet exercise, and there is scope for more refinement. For example, we could apply the regional BBS changes; we have not accounted for changes in number of households over the years; all of these surveys were in England, and there are not enough of them. Maybe larger samples should be given more weight as should more recent samples. 

With more data from more recent local surveys of this type one could investigate other variances. Wotten et al 2002 showed that houses in rural areas are more likely to hold Swifts than in urban areas; older houses, especially those constructed before 1919 contain more breeding Swifts than houses built since then and there are regional differences in density.

Our result comes within a factor of 2 of the APEP estimate so there could be some mileage in this approach. After all, APEP say that they think that their number is an underestimate, and our estimate is bigger!

Acknowledgements

Thank you to Andy Musgrove and Stuart Newson of the BTO for encouragement to publish this. Thank you to Jake for digging out old papers with much of the data from his Concern for Swifts days and to Chris Mason for providing estimates for 6 Oxford villages.

References

Hornbuckle, J. 1984. Survey of Swifts breeding in the Sheffield area. Magpie 3: 29-33. Sheffield Bird Study Group.

Roberts, Graham C.M. 2001. The 1999-2000 Sussex breeding Swift survey, comparison with the 1968-70 survey and conservation issues The Sussex Bird Report 53

Martin, B. 1998. A survey of summering swifts in Cheshire and Wirral and their conservation status. Cheshire and Wirral Ornithological Society.

Musgrove A., Aebischer N., Eaton M., Hearn R., Newson S., Noble D., Parsons M., Risely K. and Stroud D. 2012.
Population estimates of birds in Great Britain and the United Kingdom. British Birds 106 * February 2013 * 64-100

Perrins, C. 1971. Age of first breeding and adult survival rate in the Swift. Bird Study 18: 61-70.

Richardson P. W. 1979. A Survey of Breeding Swifts (Apus apus) in Northamptonshire in 1978. Northants Bird Report 1979

Richardson P. W. 1998. Swifts in Northamptonshire 1998 - a repeat sample survey. In litt.

Wotton S. R., Field R., Langston R. H. W. and Gibbons D. W. 2002. Homes for birds: the use of houses for nesting by birds in the UK. British Birds 95 * November 2002 * 586-592

The winter movements of a pair of Swifts

It is New Year and our swifts are very very far away. It’s the middle of winter here in the north and of course mid-summer in Southern Africa. Swifts are usually faithful to both nest site and partner, but do they stay together outside the short northern breeding season? Here’s one couple's answer.

Contributed by Lyndon Kearsley

These are maps of one of my geolocator pairs showing movements in December 2011 and January 2012. They nested in a nest box above a busy school playground in Hechtel, Limburg Province, Belgium. The coloured dots are smoothed average 24 hour locations, but remember that swifts keep flying so the accuracy is not great and the light level data weather dependent. Hopefully they are doing well and quite likely in the same regions at the moment. In 2012 they both received new geolocators and with luck we’ll know if they are equally faithful to their preferred wintering grounds come summer.

Click map to enlarge

December 2011

The female is the red track and she spent September, October and November above the Republic of Congo (Congo Brazzaville) and Gabon, leaving there on 6th December to head directly ESE to the lower Zambezi river area in East Africa. This region between Lake Malawi and the Zambezi Delta is an important wetland area with flood plains and coastal mangrove. Two large dam projects higher up-river in Zambia have reduced the impact of the summer rains but it is still a draw for west European Swifts.

The male in blue left west Congo much earlier and was, by this time, already in the south and spent the first half of the month in south east Botswana before heading into South Africa (RSA), close to the Kruger National Park, for Christmas.

As you can see they did not spend their winter together.

Click map to enlarge

January 2012

The lady goes “fly-about”. First up to the SE Tanzanian coast on 5th January where a second Belgian female breeder happened to be wintering, so an interesting area to keep an eye on. Then she flew inland towards the Lower Zambesi National Park in Zambia around 12th January, and finally south towards the Mozambique capital Maputo on 26th January returning to central Mozambique at month’s end.

The male stayed in South Africa (RSA) between Johannesburg and Swaziland in the coastal highlands and remained restricted to a fairly small area in comparison to the female.

In early February they gradually moved north, getting into position for the dash north in early May back to Belgium.

More about that later.

30 year old Swift!

We were surprised to learn that there is a record of a Swift, ringed near Orléans in France at one year old, on 11th June 1967, that was retrapped 28 years, 11 months and 27 days later. So it just about reached the ripe old age of 30 years. This report appears in the French magazine La Hulotte (the Tawny Owl), Number 90 - La Nuit des Methusalem.

Written by Dick

Page from La Hulotte - click image to enlarge

There is no record of this in the Euring longevity pages, but it is not surprising that a small number of Swifts should achieve this age, given their relatively high annual survival. Indeed we predicted it in our piece How long do Swifts live?

This would established the Common Swift as the longest lived 'small bird', at least in Europe, even longer than its larger relative, the Alpine Swift at 26 years.

Swift ringing recoveries and geolocator tracks compared

It is fascinating how 50 years of ringing recoveries had already given us a clue as to where our Swifts spend the winter, but it is also surprising that some important destinations were never detected.

Contributed by Lyndon Kearsley

The BTO recently posted a piece on their Demog Blog about more ringing recovery maps on their Online Ringing Reports. 

When one checks Common Swift, the selection shows totals per country, a general map and a listing of the most interesting movements with full details.

If we look at the country totals for British ringed swifts that have been found abroad and filter this to show either locations due south (France and Iberia) or in Africa, one gets the following:

BTO foreign recoveries of Swifts Apus apus

I put these more or less in a N:S order and split into Europe, N Africa, Central Africa or East and South Africa. There were no recoveries in West Africa at all.

Unfortunately the BTO does not list full details for all recoveries and not for counties with more than a handful of them. The result is a lack of recovery dates for clumps of locations in for instance France, Spain, Morocco, DRC (Congo) and Malawi.

For recoveries where ringing and finding details are listed, I was able to annotate the BTO map as follows:

Foreign locations of birds ringed or recovered in Britain & Ireland

     Purple: ringed in Great Britain & Ireland, recovered here

     Yellow: ringed here, recovered in Great Britain & Ireland

You will note that the finding dates (often many years after initial ringing) are very consistent with the periods that Dick's Landbeach geolocator bird was in that part of Africa. Of note too is that Algerian and Tunisian recoveries are all in May (Spring) and that, although there is a string of recoveries in nearby Malawi, Mozambique only has one recovery where one would expect a great many more. The same goes for West Africa; not one recovery in that part of the continent although we now know that it is so important for a large part of the European population particularly in Spring.

Since all the points on this map are the ringing or finding locations of single individuals recovered over a span of 50 years, it is quite sobering that one tracked swift from Cambridge can join the dots. On the other hand it's just that connection that increases the value of the ringing recoveries. Conversely the ringing recoveries certainly help to confirm the quality of the geolocator results.

What an exciting time we live in. Hopefully we can use this new knowledge to lever a better time for our Swift friends too

Results from the Landbeach Geolocator Swift

by Dick Newell

We previously reported on the behaviour of one of the Landbeach Swifts, Swift 396, in its nest-box on the day that it was fitted with a geolocator, 21st July 2011.  We recorded it again on its last day, 28th July 2011, having successfully raised 2 chicks. We were therefore delighted when it reappeared in the box on 12th May 2012. It settled down to breed and we retrapped it to retrieve the geolocator on 21st June. About a week later, the chicks died, probably through lack of food, but both birds continued to visit the nest-box until 28th July, the same date as the previous year.
Since that time, the BTO has published the results of one of the Fowlmere birds retrapped in 2011, and results from birds fitted with geolocators in Sweden have also been published. So now, we can tell the story of the Landbeach geolocator swift.

click image to enlarge

The route taken by Swift 396. The red line marks its journey south and green the return journey.

The dotted green section is around the spring equinox, when positions are unreliable. 

The bird was in the Congo for the autumn equinox.

The journey followed by Swift 396 resembles quite closely a number of other British Swifts. The following is a paraphrase of Chris Hewson's analysis and account of Swift 396 (thank you Chris):

"The positions (yellow symbols) are averages for day & night positions for three day periods, this smooths the data and also compensates for movement between successive dawn or dusk events.  Points within 20 days  of each equinox are removed, because the determination of latitude cannot be achieved reliably. After 21 April, daily 3-day running averages are shown (i.e. the three day periods overlap by two days) to give a clearer idea of the migration from central through to west Africa. It probably arrived back in Landbeach sometime on 12 May but didn't go back into the box until after dark. The first time one can be sure it was back in the box was 0728 on 13 May but it was probably there in the evening of 12 May. 

It left on 28 July 2011. It then spent about 8 days in southern Spain but still managed to be in the Congo in less than 4 weeks. There is a nice cluster in the western part of the Democratic Republic of Congo, where it spent the time from around 24th August until it left on its winter 'excursion' to Mozambique around 10th December.  After the spring equinox 'blackout', it looks like it is in northern Angola before moving into Gabon then across the Gulf of Guinea to Ivory Coast / Liberia. This bird seems to cross the Gulf of Guinea from near the equator with the first positions in West Africa off Ivory Coast. While at first sight, this may be hard to believe, tracks of other birds also show birds arriving off Liberia from the south-east, which indicates an oversea approach and gives confidence that these birds fly over the Gulf as does the fact that no tracks have been seen with a bird hanging around further east than the Ivory Coast."

As if a 2000km journey across the ocean was not enough, the bird refuelled for a week in Ivory Coast and Liberia until 5th May, and then it was back in its box in Landbeach on 12th May, that is over 5000 km in 7 days!

Geolocator Swift returns to Landbeach

Contributed by Dick

This swift with a geolocator returned to its nestbox on 13th May, following its mate that returned on 11th May. It was fitted with its geolocator on 21st July 2011, and then continued returning to the nest-box until the chicks fledged on 28th July.
The video shows the bird with the geolocator returning first, followed over 20 minutes later by its mate bringing the first feather in of 2012. The initial greeting looks more like a fight, but they soon settle down for a night of mutual preening.