Fauna surveys

Fauna surveys

Big mammals

The methods listed below allow the determination of ecological parameters of the populations in question (e.g. density, population structure, relative density, population distribution, habitat use).

  • Extensive census by observation unit (block count) (target: large ungulates): daytime, with fixed and/or moving operators in Reference Sectors (RS) and Detection Units (DU), to be counted on subsequent days. Annual frequency, to be carried out in favourable periods (e.g. wintering).

  • Extensive census or spring night sampling with flashlight (target: carnivores, large ungulates, lagomorphs), driven by vehicle, aimed at an overall quantification of the presence along routes or in open areas. Annual frequency, from April to June.

  • Extensive census or bellowing sample (target: deer): night-time acoustic detection of bellowing adult males. Annual frequency, during the reproductive period (autumn).

  • Presence index detection (target: large carnivores, mustelids, ungulates, lagomorphs) for an estimate of abundance (e.g. scrubs, tracks, burnings, markings with feces) in relation to an area or transect (strip transect). Frequency: potentially achievable throughout the year.

  • Counting of active lairs (target: large carnivores, mustelids) in a properly patrolled area for the calculation of an index of the abundance of the resident population. Annual frequency (springtime).

Small mammals

The methods listed below for monitoring microteriofauna (moles, shrews, voles, dormice, mice, rats) usually do not allow to obtain an estimation of population density, since it is often impossible to refer to a given surface measure; however, the counting and identification of captured individuals provide an index of population abundance as well as a representation of biodiversity.

  • Wads analyses: collection and dissection of wads, undigested fragments of prey (bones, teeth, hair), compacted in a characteristic way, regularly regurgitated by some birds of prey (especially nocturnal Strigiformes); this operation allows the identification of micro-mammals’ species that have constituted the predator’s meal, thus being able to infer its presence.

  • Live traps: sampling based on the arrangement of non-lethal traps of different types, at regular intervals, along a transect or in such a way as to form a “catch grid“; in the second case an estimation of population density can be obtained, since the number of samples taken can be traced back to the sampling area. Catches shall be taken for at least three consecutive nights; the release of captured specimens is always foreseen.

Reptiles and amphibians

Data on the Italian herpetofauna are collected within the project “Atlas of Italian Amphibians and Reptiles”, by the Italian Herpetological Society, of which we adopted some sampling methods:

  • Direct observation: research and counting of specimens along transects or within representative areas of the territory. The method allows to obtain qualitative or semi-quantitative data (as the sampling effort increases).

  • Manual capture: research and capture of specimens after research in typical micro-habitats or using special equipment (falling or floating traps, loops, nets). By increasing the sampling effort, it is possible to proceed with the determination of ecological parameters that allows to obtain mainly qualitative results, such as the Petersen Index, obtainable by recapturing the specimens previously caught and marked (“method of subsequent catches”).

  • Acoustic lures: counting the males’ lures at the point counts (only possible for singing amphibians and limited to the breeding season).

  • Other methods can also be applied to support the previous ones, such as the night transects carried out on a vehicle (night driving, useful for monitoring night amphibians) and / or the collection and identification of specimens killed on the roads (roadkill analysis).

All the proposed methods are applicable only to periods in which the fauna component is active (spring-autumn). Whatever the adopted technique, the release and safety of the captured specimens is guaranteed.

Birds

The birdlife census is a reference point for biodiversity monitoring, comparison of habitats, pre- and post-treatment surveys.
Considering the importance that wild birds also have in community or international contexts (Directive 79/409/EEC “Birds”; Ramsar Convention, relating to fauna of humid environments), the correct monitoring of natural populations is particularly important with a view to sustainable land management and/or infrastructure design.

  • Relief through point counts: identification of nesting species by listening to birdsongs from an adequate number of points; this qualitative method is particularly suitable for woodland environments and/or difficult to observe species.

  • Relief on linear transects: contacts’ recording (visuals or auditory) obtained by an observer during the time taken to complete a predetermined length transept; species, number of individuals, activity, substrate and distance from the transept of observed birds are therefore reported. The method is basically qualitative; however, by increasing the sampling effort (35-40 recordings, monthly sampling repetition), it is possible to obtain semi-quantitative information and proceed with the calculation of fauna indexes (e.g. species richness, abundance, diversity) and density estimates.

  • Particularly elusive or rare species (e.g. raptors) may also require the application of special methods, such as listening at particular times of the day (e.g. at sunset for strigiforms), search for nests or signs of presence, singing response induction (census at playback).

  • Colonial species (e.g. Laridae, herons) also require specific techniques to estimate the density of identified colonies. No censuses are carried out using ringing techniques.