3.3 Presence/Not Detected

Recommended method(s): See Tables 2 and 3 for species-specific recommendations.

All that is required for presence/not detected is that birds be detected and identified therefore most detection techniques can be used. Consequently, data can be accumulated gradually over time from a variety of sources.

Observation Stations - Presence/Not detected for all stages of life cycles (see Tables 2 and 3). It is the preferred method for counting breeding pairs, and broods for all but the most conspicuous species (e.g., swans and geese).

Helicopter Surveys - Presence/Not detected for detecting breeding pairs, broods, or incubating adults for the most conspicuous species (e.g., swans, geese, Sandhill Cranes), or breeding pairs or broods of low density species (e.g., loons).

Boat Transects at sea - Presence/Not detected for detecting non-breeding birds on the ocean and in large wetlands (e.g., lakes or rivers) or along shorelines. Boat transects are suitable for surveying flocks of moulting and wintering sea birds in defined areas (Savard 1982).

Aerial Transects - Presence/Not detected for breeding birds (swans, geese and Sandhill Crane), brooding ducks, and non-breeding bird counts.

Aerial transects are suitable for reconnaissance surveys to gain information for planning more intensive surveys, and to locate distribution (presence/not detected) at all times of the year. For difficult to see species (sea ducks) or for recording the presence of specific breeding stages (pairs, broods), a helicopter may be more effective than a fixed-wing aircraft.

Ground Transects - Presence/Not detected for detecting breeding pairs and broods of Sandhill Cranes, and for detecting non-breeding bird counts through wetlands (travelled by foot).

Call Playbacks - Presence/Not detected for breeding Pied-billed Grebes, and likely for other secretive waterbirds vocalizing during the breeding season. Other vocal and secretive, or at least sometimes hard to detect, waterfowl and allied species for which call playback might work include loons, Canada geese, coots, and Sandhill Cranes.

3.3.1 Protocol

*For details see the Relative Abundance Section. The notes below are specific to Presence/Not Detected Surveys.

Sampling Effort

It may be difficult to detect birds at low densities. More effort may be needed to sample birds at low densities (i.e., increase the size of the area sampled and the time spent sampling per unit of area).

Field Procedures

• Observation / Call Playback Stations - All birds are recorded that can be identified from a station (unlimited radius).
• Transects - All birds are recorded that can be identified while travelling along a transect (even those found outside the fixed-width).

Data Analysis

• List the species present in the study areas surveyed.
• Plot the occurrence of a species using some map-based units. The size of the map unit depends on whether the habitat is coarse or fine grained with respect to the species' distributions. All map units should be surveyed at a consistent level.
• The analysis with presence/not detected data depends on the objective of the inventory effort. The table below highlights suggested analysis methods for the given RIC objectives.

Table 6. RIC objectives and analysis methods for presence/not detected data.

RIC Objective	Analysis methods	Program
Document species range	Analysis to ensure adequate effort Negative binomial estimate1	See RIC manual No.1, Section 5.2
Determine habitat associations	Logistic regression	Generic statistical analysis software
Detect change in distribution over time	Use relative abundance methods and regression techniques	Generic statistical analysis software

¹ See RIC manual No.1, Section 5, for more details on negative binomial methods.

Quantifying probability of detection: The main purpose of these methods is to document species geographic ranges. From a statistical point of view it is important to attempt to quantify the detection probability (as a function of population density, population spatial distribution, detection probability, sampling effort, and other covariates) for a species to allow a general estimate of the optimal amount of effort needed for surveys. Also, if an attempt is made to quantify probabilities of detection, a more statistically conclusive statement can be made about possible reasons for not detecting a species as opposed to a simple "none were found" conclusion. A simple way to estimate probability of detection is through the use of the negative binomial distribution with data from relative abundance surveys. This procedure is detailed in RIC manual No.1, Section 5.

Documenting changes in species distributions: If the objective is to detect changes in geographic distributions over time, a more intensive survey regime using relative abundance methods is recommended. This will allow a probability level to be associated with changes in distribution or apparent local extinction. A conclusion that species have become extinct in an area using presence/not detected methods will be difficult given that no estimate of survey precision is possible using current methods. More exactly, it will be difficult to determine if a species is not detected is due to lack of sample efficiency or actual demographic extinction.

Documenting habitat associations: If determining habitat associations is an objective, it will be important to document habitat types at the scale of waterfowl home ranges.