Nightjar

Bird Atlas 2007-11, with its focus on daylight survey work, may not have been designed to collect records of Nightjar but the species maps that will be published next year give a good picture of the distribution of this remarkable bird, with some encouraging gains since the 1988-91 breeding atlas. There is tremendous interest in Nightjars and many people presumably made an effort to add additional visits to likely squares in order to add those important dots for their patches.

Using the not-quite-fully-checked set of data for Britain, and excluding ‘summering’ and ‘present’ reports, Nightjars were recorded as possibly, probably or confirmed as breeding from 327 10-km squares between 2008 and 2011, compared to 274 in 1988-91 and 563 in 1968-72. Similar figures for Ireland are 5, 11 and 93 (with the most recent figure first). Even when taking account of the potential biases caused if there were differing levels of effort in the different surveys, these are large changes. There are far more ‘possibles’ and ‘probables’ this time around, with only one confirmed 10-km square in Ireland and 108 in Britain.

Within regions, across the timescale of the three breeding atlases, there have been significant changes to the availability of habitat, especially linked to the cropping patterns of the afforested areas of southern Scotland and within Wales. Looking at the map that shows the history of change over the forty years there are two over lapping patterns, with a clear shrinkage of core breeding areas, especially between 1968-1972 and 1988-91, overlain with what seems like a more random pattern of departures and arrivals in other parts of Britain.


 

Nightjar historical change map 

This map which shows historical changes. Solid black down-pointing triangles indicate declines since 1988-91 and open black down-pointing triangles losses in the period between 1968-72 and 1988-91. Solid red up-pointing triangles are recent arrivals and open red up-pointing triangles indicate colonisation between 1968-72 and 1988-91. Darker pink areas show breeding locations occupied through the whole period, with lighter pink indicating presence in the first and most recent breeding atlases but absence in 1988-91.
 

So, where do birdwatchers go to see Nightjars?  In Ireland, it's now hard to find the species and in the English Midlands most of the formerly reliable sites have been unoccupied for over twenty years, though Cannock Chase and Sherwood Forest still support birds. In southern England breeding birds are widespread within suitable habitat but more concentrated in key sites, having benefited from heathland and forest management, and East Anglia has seen some recent re- colonisation outside the traditional strongholds. Within plantations, as in northern England, Scotland and particularly Wales, Nightjars move territory to areas of young growth within the forest production cycle. Annual studies by keen ornithologists in several of these forest areas help to explain patterns which may look random on the twenty year scale of atlas projects but can be explained by changes to management patterns when looked at as part of a continuous study.

In a summer such as this, when the effects of weather patterns in the UK have less than subtle effects on breeding performance, it is easy to understand that population levels and distributions of Nightjars within the UK are influenced by the conditions available to Nightjars in the breeding season. However, this is not the whole picture. The tagging project featured in the July/August BTO (PDF, 116.85 KB) News illustrates just how many different areas of both Europe and Africa are important to a single Nightjar.

Nightjar LB12420 Route Map

Migration tracking of Nightjar LB12420. Orange ellipses indicate autumn
migration locations, blue indicates winter locations and yellow indicates spring
locations. Solid lines show actual routes of movement. Broken lines indicate
likely routes of movement.

Some of the Nightjar hot-spots are very similar to those emerging for Cuckoos and Swifts. Not only do these tracking projects reveal amazing information about the lives of once-mysterious birds, they also make connections to the habitats available within the vast continent of Africa. Geography comes alive, as we consider the key crops of individual countries, the pressures of growing human populations and the variability of annual weather patterns.

Personally speaking, as a birdwatcher who started to really develop my passion for birds in the seventies, I have a strong memory that the weather patterns in the Sahel, the area south of the Sahara, are important to species such as Sand Martin, Whitethroat and Sedge Warbler. This understanding – together with the variability in arctic productivity that we see when waders return each autumn – has helped to create in me the realisation that the effects of climate and habitat change cross continents. I wonder if the new generation of teenage birdwatchers will develop similar feelings about the forests of the Congo and spring migration staging areas in western Africa as the deep-seated ones I have about the Sahel?

By Graham Appleton