Ringing recoveries confirm higher wader mortality in severe winters

Abstract

Periods of severe weather can result in significant mortality in bird populations. In Britain there is a system of voluntary, followed by official, bans on wildfowl hunting in coastal areas during periods of severely cold weather, in order to minimise disturbance to bird populations during these periods of energetic stress. The effectiveness of such hunting bans will be influenced by the spatial variation in severe weather and consequent mortality. Reports of dead ringed birds (recoveries) clearly show that the number of recoveries of waders increases in severe weather periods. The distribution of this mortality in severe weather varies between species and both temporally and spatially. It is suggested that the numbers of recoveries received in severely cold weather could be monitored and used to confirm that increased mortality is occurring.

Weather conditions and conspecific density influence survival of overwintering DunlinCalidris alpinain North Wales

“…McCulloch & Clark (1992) found that Dunlin selected estuaries with higher minimum temperatures, as well as more westerly sites. Clark (2004) found increased mortality rates with severe freezing weather, but primarily on the east coast of the UK, particularly on the Wash. This increase in mortality was not nearly as strong on the west coast, even in smaller birds such as Dunlin.…”

“…Wader mortality has been shown to substantially increase during periods of very cold weather (Dugan et al 1981, Davidson & Evans 1982, Davidson & Clark 1985, Clark 2004, 2009). The freezing temperatures affect the birds directly, by increasing metabolic stress (Dugan et al 1981, McCulloch & Clark 1992, Thompson & Hale 1993, Burton & Evans 1997, Warnock et al 1997, Kelly et al 2002 and indirectly, by affecting the behaviour of their prey (Goss-Custard 1969, Davidson 1981, as well as occasionally freezing the surface of the upper tidal mudflats (Thompson & Hale 1993).…”

“…It is widely acknowledged that severe weather events can have detrimental consequences on wading bird populations (Evans 1991, Yalden & Pearce-Higgins 1997, Conroy et al 2002, Clark 2004, Altwegg et al 2006) and these effects have been studied in depth in several species (Dugan et al 1981, Peach et al 1994, Insley et al 1997, Burton et al 2006, Duriez et al 2009). For example, Common Redshank Tringa totanus and Dunlin Calidris alpina have been shown to be susceptible to periods of cold winter weather, when mortality increases significantly (Clark 2004).…”

Survival of Afro‐Palaearctic passerine migrants in western Europe and the impacts of seasonal weather variables

“…Weather may affect survival directly, for instance through increased metabolic requirements in cold weather (e.g. Clark , Pendlebury et al . ) or strong winds during migration (e.g.…”

Selective mortality of waders during severe weather

“…Birds may be killed or forced to move by severe weather (Dobinson & Richards 1964, Davidson & Evans 1982, Ridgill & Fox 1990, Mitchell et al 2000, Clark 2004), sometimes directly, but generally because they are unable to obtain sufficient food, particularly if energetic demands increase due to a fall in temperature or increase in wind speed. For example, short-term behavioural responses by animal prey to changing weather may change prey availability, making it more difficult for birds to find food.…”