The most used methods
To date, the most used method for hare monitoring it was the night count with halogen headlight conducted from a vehicle. A system believed to be able to provide fairly reliable estimates of the density of this lagomorph. Today, however, thermal viewers are available, much more sophisticated and expensive instruments that can find an ideal use in the wildlife field for counting species with crepuscular and nocturnal habits. To verify the usefulness of this tool for counting hares within wildlife and hunting institutes, the FIdC Faunistic and Agro-environmental Studies and Research Office carried out a comparative test between thermal visor and headlight in twenty sample areas of the 'Central Italy. In practice, the same paths were crossed a few minutes apart by an observer with a headlight and another with a visor to evaluate the difference between the two instruments in terms of contactability of the animals.
Sightings and recognitions
The test showed that with the thermal viewer it is possible to identify a greater number of animals (approximately + 35%) largely due to the fact that with this instrument the distance at which the hare can be spotted and recognized increases (even at more of 300 m). As a result, the monitored area increases by approximately 25%. On average, the density estimate increases by approximately 12% in favor of the viewer. The difference in contactability between the two instruments was found to be highly variable depending on the environmental conditions of the terrain. In the case of very low and uniform vegetation, such as in fields sown with winter cereals, the difference depends almost exclusively on the greater observation distance, while where the vegetation rises even a few cm (medicine) or in the presence of scattered vegetation of greater height (typical of annual uncultivated crops) the viewer allows you to identify many more individuals with differences even greater than 50%. In fact, in order to identify a hare with the headlight, the reflection of the eye must be detected, which is not always possible in the case of slightly higher vegetation or where scattered herbaceous or shrubby vegetation projects a shadow that can hide the subject . The thermal viewer on the other hand, since it is based on the detection of body heat, does not have this problem and it is enough to frame a part of the animal to detect its presence.
The problem of vegetation
In summary, the thermal viewer was more precise and effective than the headlight in most of the environmental situations typical of our countryside. It should be kept in mind that even the viewer cannot "see" through the vegetation, so for the hare, a height greater than 30-35 cm remains problematic even for this instrument. The thermal viewer can be used at any time of the year, but the ideal use is during the cold months which make the contrast between the heat of the animal and that of the ground more evident. The possibility of video-recording sightings provided by many instruments on the market represents a further advantage because it allows for a retrospective analysis of the work done. It is essential, however, that the instrument used is of excellent quality and equipped with a rangefinder to measure observation distances, a very useful parameter for calculating density. The lighthouse, however, should not be retired too hastily, in conditions of intensive agriculture, on the plains, with low and uniform vegetation, it provides performance comparable to that of a thermal viewer. Furthermore, it remains a useful tool when we have uncertainties about the identification of the species: the light from the lighthouse can resolve many doubts. In short, it is a tool that is always worth carrying with you during night census operations (Dr. Francesco Santilli – Federcaccia Faunistic and Agro-Environmental Studies and Research Office).