Causes of change

The recovery of this species coincided with the availability of suitable open ground habitat resulting from the felling of forests planted in the late 1920s and 1930s, the clearance and restocking of areas damaged by storms in the late 1980s and, importantly, the restoration of heathland habitats. Management, protection, restoration and re-creation of key habitats remains critical for maintaining Nightjar numbers.

Further information on causes of change

The historical population decline and contraction of range have been attributed to large-scale losses of heathland to agriculture, construction and afforestation (Conway et al. 2007, Langston et al. 2007b). Recovery has coincided with more suitable open ground becoming available through the felling of forests planted in the late 1920s and 1930s, the clearance and restocking of areas damaged by storms in 1987 and 1990 and the restoration of heathland (Scott et al. 1998, Ravenscroft 1989, Morris et al. 1994, Conway et al. 2007, Langston et al. 2007b). While most recent increase has been consolidation within the existing range, there has been colonisation of conifer plantations at higher altitude in southwest England and on the North York Moors: this might be a density-dependent effect as new habitat becomes available or could be evidence of positive effects of climate change (G.J. Conway pers comm).

Prospects for further recovery may be limited, however, due to a reduction of suitable habitat as newly restocked forests grow and to the effects of human disturbance: studies have found that concentrated human disturbance can affect territory densities (Liley & Clarke 2003; Pouwels et al. 2020) and that nest failure is most likely in areas heavily frequented by walkers and dogs (Langston et al. 2007a). However another study, in Thetford Forest, concluded that recreational disturbance was not a factor in nest failure (Dolman 2010), and a study in Nottinghamshire found that, although territory selection was influenced by disturbance, there appeared to be no concurrent impact on breeding success (Lowe et al. 2014). The Thetford study also observed that all nest predators were mammalian (foxes and badgers), but their impact was unlikely to affect Nightjar population size (Dolman 2010). In Switzerland, a study concluded that denser vegetation regrowth and lower prey abundance hindered reuse of previously occupied sites (Winiger et al. 2018); however this was directly contradicted by a subsequent study in the same area which concluded instead that prey abundance had not changed and that recolonization of apparently suitable sites was prevented by light pollution (Sierro & Erhardt 2019).

Burgess et al. (1990) reported that, at Minsmere, creating more edge habitat and providing abundant nest sites resulted in an increase in the Nightjar population (see also Conservation Actions section, below).

New tracking studies suggest that Nightjars consistently forage in non-forest habitats, such as grasslands and semi-natural habitats, sometimes on farmlands, and that the availability and management of the adjacent landscape could affect Nightjar populations (Evens et al. 2017, 2018, Henderson/Conway, in prep.). A small-scale test study in Thetford Forest found that non-forest habitats have higher moth biomass, which Nightjars exploit, although further structured surveys are needed (Henderson et al. 2017). Tracking also suggests that some individual Nightjars may specialise by foraging within one particular habitat type whilst others follow a more generalist approach, and that habitat heterogeneity may help increase local populations by benefiting both specialists and generalists (Mitchell et al. 2020).

Information about conservation actions

Management, protection, restoration and creation (or re-creation) of key forest and heathland breeding habitats remain critical for the long-term conservation of Nightjar (Ravenscroft 1989; Morris et al. 1994; Scott et al. 1998; Conway et al. 2007). Open spaces including clear-felled areas and young stands within larger forests are important, and wide forest tracks can create additional habitat for Nightjars (Verstraeten et al. 2011). Forest management should include rotational cutting to ensure a mosaic of different aged stands are available, as well as actions such as creating glades in woodland and sculpting woodland margins to increase the area of edge habitat, leaving woodland shelter belts standing and providing abundant potential nesting sites, mainly by clearing small patches of heather from the base of small birch trees, (Burgess et al. 1990). In Thetford Forest, Dolman & Morrison (2012) found that density of Nightjars was highest in areas of restock at pre-thicket stages (6-10 years) and that management of conifer plantations plays an important role in determining the population of Nightjars. Radio-tracking there indicated that a variety of growth stages is important for this species and that grazing of open habitats within and adjacent to the forest will also be of benefit (Sharps, K. et al. 2015). Areas of heath and bare sand should also be created or maintained within the open patches (Verstraeten et al. 2011).

As discussed in the Causes of Change sections, both disturbance and light pollution may possibly affect Nightjar density and therefore actions to reduce them may benefit the species, although further research is needed to confirm that these factors do impact on the population. Distance to car park, distance to road and openness all influence visitor density, and therefore changing the location of car parks can be an effective tool to manage visitor numbers (Pouwels et al. 2020)

Recent tracking studies suggest that Nightjars also forage outside forests in grassland and other semi-natural habitats including farmland (Evens et al. 2017; 2018; Henderson/Conway in prep), so the habitat requirements are not necessarily limited to the woodland area in which the birds are nesting, and a wider landscape scale approach may be needed in addition to local site management.