Wednesday, 22 October 2014

Bird Ringing Summary, Titchfield Haven - October 2014

With the autumn migration season at the Haven gradually drawing to a close, and the first Redwings and Bramblings of the autumn returning, I have been playing around with some of the species ringing totals. But rather than just focus on the last five years, I have looked back to 1998 at a selection of species. As well as looking at the capture totals between 1998 and 2014, it has also allowed me to look at the general trend of each species over that period. Initially I have looked at those species that we are unlikely to catch again this year but as the season progresses I will add other species. The table below provides information on a selection of passerines, including those that are regular and others that are more uncommon.

The table above looks at the ringing totals between 1998 and 2014 for a selection of passerines.
The totals in red are record years, the total figure is the total number of birds ringed in that year,
not just the total of the species shown.

As I have stated previously the total of 270 birds for Willow Warbler was a record for the site by a good number, as illustrated above. Between 1998 and 2014 the previous highest total was 158, and we have come close to catching 150 birds on three other occasions. Looking at the trend for the last 16 years there is a steady increase. It is difficult to interpret what this means but certainly the number of birds being caught each year is showing a gradual increase.

The Grasshopper Warbler total ended with a total of 340 birds, which is the fifth highest total ever for the species. Once again there is a strong upward trend for the species but that is likely to be slightly skewed by the amazing total of 950 birds in 2011.

The total of 151 Common Whitethroats is the second highest total for the species and once again the trend for the capture totals is a strong upward one. Looking at the totals it is evident that three of the last four years have produced the first, second and third highest totals which could suggest that the species has been having productive breeding seasons recently.

Another species showing a strong upward trend is Garden Warbler and this year's total of 67 was the third highest ever. It is interesting to note just how few birds are ringed annually, in comparison to other species such as Common Whitethroat and Blackcap. Could this indicate the smaller numbers of birds that breed in the British Isles or do Garden Warblers not migrate through the Haven in high numbers?

A species that we get asked about every year when we carry out public ringing events is the Aquatic Warbler. It is a species that is on most Hampshire birders wish list and a species that I have been fortunate to get to grips with on many occasions. Since 1972 only 16 Aquatic Warblers have been ringed at the Haven; the first was in 1977 but 15 have been between 1998 and 2009. We have had several years with multiple captures with the peak being 2006 when four birds were ringed.

Aquatic Warbler - Titchfield Haven 2009

Since 2009 we have not caught an Aquatic Warbler at Titchfield Haven and subsequently there is a strong downward trend for the species at the Haven. Aquatic Warbler is classified as Vulnerable and has declined rapidly in previous years due to the destruction of its habitat. Its decline has been stopped in some areas due to intensive management but in countries like Hungary the species has been quoted as declining to extinction. The decline in the species may be reflected in the lack of birds being caught at the Haven in recent years.

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