to help interpret changes in bird numbers. This can be done by taking measure-
ments of sward height against the graduated side of a Wellington boot as you
walk across the field or by using a sward stick (see Chapter 11).
Three types of domestic animal are commonly used to graze grasslands: cattle,
equines (horses, ponies, and donkeys), and sheep. Cattle feed by ripping off tufts
of vegetation and are the first choice for producing fine-scale variation in sward
structure and patches of bare ground. Equines and sheep nibble the vegetation
and are more selective in the plants they remove. If they like the vegetation, they
nibble it uniformly short, but if they do not, they will ignore it. They therefore
produce little fine-scale variation in the sward, but at moderate grazing densities
can create coarse-scale variation comprising short, uniform lawns and dense,
rank areas. Judicious grazing, particularly by cattle, is therefore better than cut-
ting or burning in providing suitable conditions for birds requiring a close juxta-
position of suitable nest-sites and ranges of feeding conditions. Grazing
influences vegetation composition by encouraging unpalatable and low growing
plants that can tolerate repeated defoliation, particularly grasses and rosette-
forming species.
14.5.4Minimizing nest and chick loss during management
If done during the breeding season, cutting and burning destroy nests and chicks
(Kruk et al. 1997). Grazing animals can trample nests (Beintema and Müskens
1987; Green 1988). Vegetation removal should therefore ideally be undertaken
only outside the breeding season. This may be impractical on grasslands where
management is driven primarily by agricultural requirements and it may allow
the sward to grow too tall for chick rearing, for example, by Lapwings Vanellus
vanellus. One option is to graze or cut fields adjacent to those with nesting birds,
so that adults can take their chicks to feed in these fields. Another is to graze fields
with nesting birds at low stocking densities, with the aim of offsetting any
decrease in nest survival caused by trampling, with an increase in chick survival
due to better chick-rearing conditions. The type and age of stock also influence
the proportion of nests trampled (Beintema and Müskens 1987). Alternatively,
entry of stock or cutting can be delayed at least long enough to increase nest
survival to levels sufficient to maintain the population (e.g. Kruk et al. 1996).
For species whose nests can be easily located, such as Lapwings and Black-tailed
Godwits Limosa limosa, nest survival can be monitored to determine the propor-
tion lost to trampling. This information can be used to fine tune grazing regimes.
Nests of these species can also be protected from trampling using nest protectors
(raised metal grilles placed over the nest), or from mowing by marking nests and
mowing around them (Guldemond et al. 1993). A novel technique is to deter
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