Sightability as a Factor in Aerial Survey of Bird Species and Communities

In: Wildlife Research, Band 12, Heft 1, S. 57

Abstract

Experimental aerial and ground censuses of waterbirds were conducted on three small, isolated bodies
of water on the New England tablelands of New South Wales. The flying height at which sightability was
optimized for the most common species was 30 m. Aerial and ground counts were significantly
correlated for most species on the three watar bodies. Black swan, swamphen, coots, musk ducks and
maned ducks were counted in equivalent or greater numbers from the air than from the ground on at
least one water body. Other species were counted in lower numbers from the air than from the ground. A
fairly high precision in the aerial-ground relationship for the most abundant species indicates that aerial
survey can be a useful procedure for obtaining indices or estimates of the population sizes of these
species. However, differences in sightability between species and between types of water body indicate
that indices should be used and interpreted with caution. Other bird species from a variety of habitat
types which are also amenable to aerial survey are discussed, and some recommendations for aerial
surveys of birds are provided.