Read the LAMP report - SOUTHERN AFRICAN BIRD ATLAS PROJECT

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Read the LAMP report - SOUTHERN AFRICAN BIRD ATLAS PROJECT Powered By Docstoc
					           SOUTHERN AFRICAN BIRD ATLAS PROJECT

       REPORT ON THE LONG AUTUMN MIGRATION PROJECT

                                        (LAMP2009)

What were we trying to achieve?

From 1 March to 31 May 2009 all atlasers contributed to LAMP, the Long Autumn Migration
Project a mini-project within the South African Bird Atlas Project. The objective of LAMP was
to document the timing of bird migration from South Africa, Lesotho and Swaziland in
autumn 2009.

Why did we do LAMP?

The importance of a project like this is that the timing of migration is predicted to be one
aspect of the annual cycle of birds that is impacted by global climate change. With springs
shifting earlier in Eurasia, we anticipate that migrants to Eurasia need to leave southern
Africa progressively earlier in order that the timing of peak demand for food by growing
nestlings coincides with the maximum flush of food availability early in the northern summer.
If they do not adjust their timing of migration, it follows that they will arrive on the breeding
grounds at the same time, but spring will be so far advanced that they might still be
incubating eggs when the big food flush occurs, and breeding success will be poor.

What did LAMP actually achieve?

This is a brief report on LAMP, based on data that had been submitted by the end of June
2009. This is not a final report, because, in the nature of things, it takes many months for all
checklists for a period to be submitted.

The number of registered atlasers who participated in LAMP was 425. At the end of May, the
total number of participants in SABAP2 since it started in July 2007 was 522. In other words
81% of SABAP2 atlasers were active during the three-month LAMP period.

The total number of checklists submitted to LAMP was 3722. This means that, on average,
each LAMP atlaser submitted 8.8 checklists. The numbers of checklists submitted in March,
April and May were 1305, 1249 and 1168 respectively, 35%, 34% and 31% in each month.
Given that May is the month for which most late submission will be for, the final spread of
checklists between months will be almost even.

The number of different pentads visited during LAMP was 1757. This means that 39% of all
pentads that had ever been visited up to 31 May were revisited during LAMP. 652 pentads
were visited for the first time. So 17% of the checklists made during LAMP were to new
pentads, indicating the extent to which observers heeded the call to go “deep” during LAMP.

69% of pentads visited during LAMP received repeat visits during the project. 137 pentads
received five or more visits, 57 received 10 or more visits, 27 received 15 or more visits, and
10 received 20 or more visits. We had (somewhat vaguely) set ourselves a target of 200
pentads with five or more visits, and fell short of the target getting 137. The target for 10 or
more visits was set at 50, and we exceeded it getting 57. The target for 15 or more visits was
set at 10, and we got nearly three times this number, 27. Pentads with large numbers of lists
represent especially valuable data for monitoring the pattern of departure. Incredibly, two
pentads got 31 visits, one got 35 and one got 36. These four pentads are close together, in
Gauteng.

The numbers of species seen in each month decreased, as anticipated during the migration
departure period: 646 species in March, 636 in April and 596 in May. The average length of
checklists also decreased: 54.7 species/checklist in March, 50.7 in April, and 47.0 in May.
May lists averaged 85% of the length of March lists. Even the March checklists were shorter
than the midsummer lists; from November 2008 to February 2009 the average length of a
checklist was 58.9 species. The 2010 edition of LAMP should probably start in February.

So what? Are there any interesting first results?

The easiest species to look at is the Barn Swallow Hirundo rustica. The histogram showing
the timing of departure in 2009 (Fig. 1) is far smoother than the histogram for 2008 (Fig. 2).
This is because the sample sizes per pentade in 2009 are on average much larger than in
2008 (3722 checklists in March, April and May 2009, compared with 1472 in the same period
in 2008).

What is clear from Figs 1 and 2 is that the timing of departure of Barn Swallows between the
two years hardly differed. In both years the reporting rate dropped below 50% for the first
time in pentade 20 (6–10 April), and few swallows were recorded after pentade 23 (21–25
April). If we carry on doing LAMP for several years, we will effectively monitor the timing of
departure. It is also striking that departure took place over a shorter period than arrival did in
2008. This is thought to be due to the fact that swallows need to be at the breeding grounds
at the start of the breeding season; latecomers will miss out of nest sites and the short
period of abundant food for growing young.




Figure 1. The timing of the departure of Barn Swallows from the SABAP2 region in 2009




Figure 2. The timing of the departure (and arrival) of Barn Swallows from the SABAP2 region in 2008

Similar results are available for other species (eg Steppe Buzzard).
Is there going to be LAMP in 2010? How should it differ from LAMP in 2009?

This kind of data becomes incredibly valuable if data collection is maintained on an annual
basis. The SABAP2 protocol represents an excellent fieldwork approach to collecting data
on the timing of migration on a national scale. Because we are able to measure when the
reporting rate (or any other statistic) reaches 50%, it represents a far sharper tool than
simply using the last dates on which a species was observed at a sample of sites. These last
dates are strongly influenced by outliers, single birds that were late to migrate, and are not
representative of the population as a whole.

As hinted above, the project team at the ADU will recommend that LAMP2010 be held as a
mini-project within SABAP2. Because departure of some species starts before March, we
will propose that it start in February and continue until the end of May.

                                                                                Les Underhill

				
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