3.2 Inventory Surveys

The table below outlines the type of surveys that are used for inventorying woodpeckers for the various survey intensities. These survey methods have been recommended by wildlife biologists and approved by the Resources Inventory Committee.

Table 2. Types of inventory surveys, the data forms needed, and the level of intensity of the survey.

Survey Type	Data Forms Needed	Intensity
Woodpecker Call Playback	Wildlife Inventory Project Description Form Wildlife Inventory Survey Description Form - General Animal Observations Form- Woodpecker Call Playback	PN RA
Woodpecker Wildlife tree/sign surveys	Wildlife Inventory Project Description Form Wildlife Inventory Survey Description Form - General Animal Observations Form- Woodpecker Encounter Transect	PN RA
Woodpecker Spot-mapping	Wildlife Inventory Project Description Form Wildlife Inventory Survey Description Form - General Animal Observations Form- Woodpecker Spot Mapping	AA
Sampling Methods	Consult with the Regional RIC Inventory Authority and with a biostatistician.	AA
All Surveys	Nest Site Description Form This is filled out only when a nest is located during the survey. It is included in the Species Inventory Fundamentals [Forms]	All

* PN = presence/not detected (possible); RA = relative abundance; AA = absolute abundance

With the exception of the Pileated Woodpecker, there is not enough information on the logistics of surveying particular woodpecker species to recommend species-specific methods. Therefore, the above methods may be used for surveying multiple species at one time or for surveying a single species. However, call playback and wildlife tree/sign surveys are relatively new inventory methods for woodpeckers and it is not known how successful these methods will be for each species. Thus, it is important to consider differences among various woodpecker species and develop inventory strategies accordingly.

3.3 Presence/not detected (possible)

Recommended method(s):

Call playback/drumming imitation surveys are recommended as the most efficient survey method during the breeding season, especially for those species that are known to respond to call playback, occupy relatively large home ranges and/or are otherwise difficult to detect (refer to Section 2).

During the non-breeding season when birds are less conspicuous, wildlife tree and indirect sign surveys for woodpecker feeding, roosting and nesting excavations are recommended as indicators of woodpecker presence.

General considerations: While call playback surveys or encounter transects for sign of woodpecker activity can be used to determine presence/not detected status, their uses should be carefully considered because they may be inefficient uses of resources for determination of simple presence/not detected surveys. In some situations this method may be necessary as the only possible method to locate secretive woodpeckers, or they may be done with little cost, but there is a great statistical problem in specifying the probability of absence. The asymmetry between recording a species (= know it is there) and not recording a species (could be there but not enough effort to find it) is a serious statistical problem with both call playback and encounter transects. See the Species Inventory Fundamentals manual for a discussion of survey effort needed to detect species which exhibit low population levels.

Sampling Design and Sampling Effort: The number of sample sites and the number of times each site is re-visited will vary with the rarity of the species and variability of the habitat. Adequate sampling effort is required to ensure that data collected is representative of the surveyed area. For presence/not detected surveys, a graph of species detected as a function of call playback points or distance travelled will approximate optimal search effort to detect woodpecker species (refer to RIC Species Inventory Fundamentals manual, Chapter 5, section 5.2). Unfortunately, since the diversity of woodpecker species is expected to be smaller than 10 species in any given study area in the province, these graphs may be ineffective. Therefore, they should be used only as a general guideline. Also, these results will only be applicable to the season and area in which the survey was conducted. Other factors such as weather, observer experience and habitat types will also affect the number of species detected. Therefore optimal sample effort for presence/not detected surveys will have to be determined on a study specific basis.

The Project Biologist must stratify the study area according to the objectives and hypotheses of the study. Typical habitat for many woodpeckers includes open, mature forest with an abundance of dead or dying trees suitable for foraging. However, the habitat descriptions for each species as described above should be consulted to determine habitat strata. Some example categories include:

• general habitat types (e.g., seral and structural stages, tree species composition, riparian zones; abundance of dead or dying trees);
• biogeoclimatic units (subzone, variant, site series; see Meidinger Pojar 1991) or ecoregion classification (ecoregions, ecosections; see Demarchi 1995, 1996);
• silviculture systems or land allocation (harvesting regimes, silviculture practices, wildlife tree retention areas, ecological reserves, etc.); and
• natural disturbance history (fire, insects, disease).

Biologists should focus their efforts on strata which have the highest potential population levels if presence/not detected is the principal objective of survey efforts.