Nightingale survey shows continuing decline in numbers

As our survey of nightingale numbers across Hampshire and the Isle of Wight concludes, a worrying pattern of decline continues to emerge.

As you may recall, earlier this year we asked for help in conducting surveys as part of our Nightingale Recovery Project. With the help of many dedicated volunteers were able to survey large areas of suitable nightingale habitat across Hampshire and the Isle of Wight throughout the 2018 breeding season. Sadly, the results of these surveys have confirmed a further decline in the numbers of this iconic and beloved species.

Recently published survey data from across the UK has shown a decline in nightingale numbers of 59% between 1995 and 2016*. The results of our 2018 survey have supported these findings: when compared with the last British Trust for Ornithology nightingale survey, which took place in 2012, our data shows a decline of 78% in Hampshire and 33% in the Isle of Wight. You can find a full breakdown of our findings below.

The reasons for this decline are still unclear and could be due to many factors, including loss of habitat on wintering grounds and stopover sites during migration. The Isle of Wight has fared much better than Hampshire; this may be a result of lower grazing pressure due to a lack of deer, which creates the denser shrub layer that is preferred by nightingales. However it is likely that development pressure and loss of suitable habitat in our two counties may also be contributing.

One worrying feature of our results is that in both counties a significant proportion of the respective nightingale populations were recorded in just one locality, making them extremely vulnerable to land use change. Casbrook Common, for example, recently saw the destruction of its nightingale habitat, and this year two males held territory there but did not appear to attract mates.

We previously reported that this spring saw many species of birds arriving late and in lower numbers than usual, so we are hopeful that next year may see a rise in numbers across the board. We were also unable to gain access to some areas which have supported nightingales in the past, and may have done so this year.

We would like to thank all those who gave their time to help with this year’s surveying effort – we could not have gathered this vital data without you, and are extremely grateful for your support. We will continue to work with land owners and partners to ensure that suitable nightingale habitat is present in core areas, and look to expand the available habitat to other priority areas.

Full survey results

The Isle of Wight survey involved 14 surveyors covering 33 tetrads of which eight supported singing male nightingales. A total of 21 singing males were recorded during the survey period, one bird moved on after a couple of days, and therefore was considered to be a migrant, but 20 birds stayed to hold territory, of which 18 were considered to be breeding. Comparison with the 2012 BTO survey shows a decline from 30 territorial males to 20, a decline of 33%.

The Hampshire survey involved 88 surveyors covering 110 tetrads and in addition records submitted to HOS via the going birding website; 17 tetrads supported nightingales. A total of 26 singing males were recorded during the survey period, of which 12 were considered to be migrant and moved on after a couple of days, leaving 14 birds remaining to hold territory. Of those six were confirmed to have bred, and it is probable that four others did also, but unrestricted access was not possible to confirm. Comparison with the 2012 BTO survey shows a decline from 66 territorial males to 14, a decline of 78%.

*Harris, S.J., Massimino, D., Gillings, S., Eaton, M.A., Noble, D.G., Balmer, D.E., Procter, D., Pearce-Higgins, J.W. & Woodcock, P. 2018. The Breeding Bird Survey 2017. BTO Research Report 706 British Trust for Ornithology, Thetford.