Censussing distribution and population of birds along upland rivers using measured ringing effort: A preliminary study

Effects of stream acidity on non‐breeding dippers cinclus cinclus in the south‐central highlands of Scotland

“…However, all results were recorded under low water flows. Fluctuations in stream discharge mean that opportunities for feeding are generally unpredictable for Dippers in winter (Da Prato, 1981) and differences in food availability and hence foraging effort will be more important under less favourable conditions when the efficient Ormerod et a/., , 1988 food collection is at a premium. Consistent with this, data from Wales have shown birds on acid streams to be of lower mass than those in circumneutral waters ) even though they may spend up to 60% more time foraging (O 'Halloran et a(., 1990).…”

“…van Balen, 1980;Jansson et al, 1981;Kallander, 1981;Nilsson, 1987). Census results have suggested that Dipper/pH relationships evident in the breeding season may also be important among non-breeding populations, yet only one previous study has investigated autumn Dipper densities on acid rivers (Ormerod et al, 1988). The results presented here, obtained in an area remote from earlier studies, further support the findings of Ormerod et al 's autumn study, suggesting that acidity relationships noted during breeding may also apply at other times.…”

“…However, all results were recorded under low water flows. Fluctuations in stream discharge mean that opportunities for feeding are generally unpredictable for Dippers in winter (Da Prato, 1981) and differences in food availability and hence foraging effort will be more important under less favourable conditions when the efficient Ormerod et a/., , 1988. Ormerod et at., , 1988Bryant and Tatner, 1988).…”

Birds as indicators of changes in water quality

“…A range of methods involving quantitative bank-side surveys (Ormerod and Tyler, 1987;Vickery, 1991), presence/absence over 1 km plots (Ormerod et al, 1986) and catch per unit effort from ringing (Ormerod et al, 1988a) Ormerod et al , 1988a. ) Other easily measured variables reflecting deteriorating habitat quality at low pH include significantly delayed laying, reduced clutch size, reduced egg mass, reduced brood size, reduced nestling growth and inferior condition in adults, the latter shown by both live mass and condition indices (Table 5.4; Ormerod and Tyler, 1990b;Ormerod et al, 1991).…”

The use of ringing to monitor changes in the numbers and demography of birds

“…A pilot scheme would be needed. A similar scheme should be considered for river birds based on methods that have been developed and tested in Wales (Ormerod et al 1988). …”