Bird Ecology and Conservation A Handbook of Techniques

(see Chapter 1), then set the boundaries of the survey to those shown by the atlas—but be aware of any limitations to the origin ...

It is possible to mix sample and census approaches within the same survey. Thus, in some areas or habitats a census of all birds ...

interchangeable in common use. It is extremely important to understand these terms at the outset and to use them appropriately w ...

Multiple counts can be obtained by counting the same study site repeatedly in the same season, or by counting multiple study sit ...

similar numbers in different sampling units (as in Habitat B in Figure 2.4), then counts from different squares are likely to be ...

2.2 Sampling strategies We saw in the previous section that, if we are to obtain an unbiased measure of bird abundance (e.g. an ...

28 |Bird census and survey techniques (a) (b) (d) (c) Most birds Fewest birds Fig. 2.5Choosing the right sampling units to count ...

Sampling strategies| 29 is not—squares toward the center of the map would be more likely to be selected than those around the ed ...

the area of interest is broken down into different sub-areas, known as strata (singularstratum). Two simple examples of stratifi ...

what we know about the ecology of birds, it will often make sense to stratify our sample by obvious factors, such as habitat and ...

population lives in forest, then 60% of our sample should be in that habitat. Of course, there is an element of circularity in t ...

birds. A more pragmatic approach is semi-randomsampling, where sampling units are randomly selected within a predefined area. If ...

or every stratum, contains a fixed number of sampling units (Figure 2.8(b)). An alternative to random sampling that gets around ...

Stratification can be used alongside regular sampling too. For example, we could take every seventh square from a stratum where ...

field methods influence and alter each other, and they will in turn influence and potentially alter the survey objectives (Figur ...

An essential component of this method is the use of activity codes to describe bird behavior in the field. These allow observers ...

studied and probably provides relatively accurate estimates of population size (although precision, and especially accuracy, are ...

in the habitat concerned and allows species-by-species density estimation (seeDetection probabilities). It is always preferable ...

permissions, might all limit access, so that the actual routes counted will differ to some degree from the ideal routes—but such ...

counts one needs to decide on a settling time once the counting station is reached, and on the duration of the count itself. For ...