Causes of change

There is good evidence that the long-term historical decline of the Whinchat may be due to changes in management of grassland and semi-managed meadows, with reduction in habitat quality (invertebrates and structure) and scale, both being common features of existing populations. More ringing or colour-ringing data and more nest record data are necessary to fully establish productivity or survival as drivers of population change; however, recent research suggests that productivity is more likely to be the main driver.

Further information on causes of change

Whinchat is a species historically associated with lowland cultivated grassland and semi-natural meadows (Muller et al. 2005, Britschgi et al. 2006, Broyer 2009) as well as upland hill slopes (Calladine & Bray 2012). Specifically Whinchats have been shown to favour areas of long,structurally diverse tussock rich grassland, with a high density of tussocks and an abundance of perches to forage from (Border et al. 2016). Its historical decline in the lowlands has been linked to losses of suitable habitat and changes in management of grassland (Holloway 1996). Early mowing of grassland habitats generally causes direct losses of nests and even mortality of incubating females and, indirectly, makes the birds more conspicuous to predators (Gruebler et al. 2008). As the predator avoidance strategy of recently fledged young is to sit still and hide, they remain vulnerable to mowing for up to 14 days after they have left the nest, and mowing has been identified as the most important threat to this species by one European study which compared it with other factors affecting breeding productivity including predation and weather (Tome et al. 2020). Grassland intensification reduces invertebrate availability, through direct removal with cut grass, and by reducing vegetation diversity due to the application of fertilisers (Britschgi et al. 2006).

An increasing proportion of the population in Europe is now found in the uplands, where agricultural intensification has been less marked (Muller et al. 2005, Archaux 2007, Broyer 2009), although some upland areas may now be at an early stage of intensification (Strebel et al. 2015). In the UK, Whinchats are now largely considered an 'upland' species because lowland populations are now rare and confined to expansive protected habitats, such as Salisbury Plain (Henderson et al. 2014). Upland margins have become refuges for species that have declined in farmland (Fuller et al. 2006), with upland grassland and moorland now supporting the breeding population of Whinchats (Stillman & Brown 1994, Gillings et al. 2000). However, even here populations have declined in the last 20 years (Henderson et al. 2014). Calladine & Bray (2012) point out that such Whinchat habitat in the uplands is becoming more limited than may at first appear. Certainly, upland margins are vulnerable to long-term changes in grazing pressure, which has been increasing since the mid 1970s (Fuller & Gough 1999, Fuller et al. 2006).

Demographic data are insufficient to investigate whether trends in breeding productivity or survival have influenced population size in the UK, but one intensive study on Salisbury Plain found that while adult return rates were good, first year return rates were low, and did not appear to be sufficient to maintain the observed population trend, perhaps suggesting high natal dispersal even though this population appears to be isolated (Border et al. 2017); At the same time, nest losses to predation were high (Taylor 2015). Sufficient data are available to carry out modelling using survival estimates and Whinchat trends across Europe (Fay et al. 2020) , which concluded that adult mortality does not explain the trends, and that low productivity is most likely to be the main driver of European trends. Meanwhile, a study over three winters at one site in Nigeria show high survival rates of marked Whinchats within and between winters, suggesting that mortality at this site occurs primarily outside the wintering period and probably during migration (Blackburn & Cresswell 2016a, 2016b). Another study found that British breeding Whinchats winter over a wide area in Africa, suggesting that winter factors are unlikely to have driven UK declines unless they operate over a very broad scale (Burgess et al. 2020).

Information about conservation actions

There is good evidence that the decline of this species is related to more intensive habitat management. The conservation and re-creation of semi-natural habitat to maintain and increase the diversity (of both invertebrates and habitat structure) is likely to benefit Whinchats, in particular in upland areas which have become important for this species and which are also now subject to increasing agricultural intensification. These upland margins are vulnerable to long-term changes in grazing pressure.

Where Whinchats are nesting in pasture, the most important conservation action is delaying mowing. Early mowing of grassland causes direct loss of nests and also makes birds more conspicuous and therefore more vulnerable to predators ( Gruebler et al. 2012; Strebel et al. 2015). Furthermore, there are concerns that delaying mowing until after almost all nests have fledged may not be sufficient, as the predator avoidance strategy of recently fledged young is to sit still and hide meaning that they remain vulnerable to mowing for ten to 14 days after they have left the nest (Tome & Denac 2012; Tome et al. 2020). Policies to enable and encourage delayed mowing should therefore ensure that mowing does not take place until the end of this additional period of vulnerability.

As well as early mowing, agricultural intensification also leads to decreases in the availability of invertebrates in grassland habitats, in particular important nestling food (Britschgi et al. 2006). Hence actions and policies such as reducing the application of fertilisers and insecticides, and maintaining or creating a suitable habitat mosaic for Whinchats are also important.

On British moorland, Whinchats are most visible in tall vegetation, such as bracken (Allen 1995) and scrub, but mainly where there is grassy ground cover (Pearce-Higgins & Grant 2006), and vegetation height is more complex instead of uniform (Buchanan et al. 2017). In all its breeding habitats, lowland and upland, common features are perches (tall flower stems, bracken, light scrub, small trees) admixed with structurally varied, insect rich, grassland (to provide food and tussocks for nest sites). Vegetation that does not allow access to ground invertebrates is too dense to suit this species (Thompson et al. 1995), and grazing may help provide suitable mosaic conditions (Murray et al. 2016, Douglas et al. 2017). On the other hand, grazing can reduce tussock density for nest sites and reduce breeding success by exposing nests to increased risk from predation (Taylor 2015).