The footprint identification technique was developed for the purpose of monitoring individual endangered species. However, it has wider potential application; it can be used to establish a species inventory for biodiversity monitoring, and as a consequence, also in the field of environmental impact assessment.
The ability to identify which individual made a footprint may allow FIT application in forensic science and law-enforcement. It can also be of value in the natural sciences for the identification and classification of natural forms, and in other scientific disciplines (eg archaeology) and security areas where object identification and classification is used.
Individual species monitoring.
FIT can be used to census, that is to estimate numbers of individuals in a population, or sub-population of unknown size. This can be done by developing a footprint collection protocol (using an established method of sampling) specific for the area in which the census is to be undertaken.
Within this scenario, individual animals can also be linked to their individual footprints, by actually sighting the animal and making that link once. Once this has been achieved, and a library of footprints developed for the population, FIT can be used at regular intervals, to continue to monitor the population. If FIT is used in conjunction with anti-poaching routines, or alongside another monitoring method (for example in conjunction with camera-traps ) it can often be implemented at very low cost and with little extra effort.
In addition to identifying individuals within species, FIT can be used to identify at the species level. We have used it to identify between similar sympatric species, such as the black and the white rhino and the Baird’s and the Lowland tapir. It could also be used as a tool in wider biodiversity monitoring, to identify any species which leave footprints. FIT is species specific; because the technique works on the identification of geometric differences in the footprint structure, this species algorithm must be defined initially. Once a library of footprints from known animals of each species is established, the technique could be ready for field implementation for biodiversity monitoring.
Our new project, FITbase, aims to establish an endangered species database so that the necessary species algorithms can be pre-established and ready for fieldwork. The plan is to develop the database as an open-access source for non-invasive monitoring research and field-implementation.
FIT and Mark-Recapture
To census or monitor individuals in a small population, a comprehensive collection of footprints can be undertaken to ensure that prints are collected from all animals. However, research/study areas are often too large for this to be practicable, and footprints must then be collected by sampling of a subset of the area rather than a comprehensive collection over the whole area. Mark-recapture studies are often used alongside camera-trapping, where the image of the animal acts as a mark.
Footprint identification can also be employed as a recognition technique in mark-recapture studies and as such provides an opportunity to study species with identifiable tracks that are reclusive, nocturnal, or otherwise difficult to observe directly. Footprint identification also offers the considerable advantage of not requiring handling or marking of study subjects and reduces interference with their behaviour and at the same time can provide important information on population distribution and ranging of individuals.
Collection of footprints must satisfy the protocols required for the intended mark-recapture study, e.g., partitioning footprint collection effort into discrete time sets that can be interpreted as capture events, duration of the study and the intensity of sampling relative to data needs. These considerations will depend on the nature of the subject animal and the terrain they inhabit.
The important question of reliability of the identification is not unique to footprint identification but is equally relevant to any technique of recognition, e.g., camera traps, but has received the most attention in the literature in the context of recognition by genetic techniques. No doubt, the development of mark-recapture theory with an estimated error rate for identification will continue to develop. We have successfully employed mark-recapture in a short-term study of a closed population of white rhino; even with a low rate of error, further studies will help clarify the kind of misidentifications footprint identification is likely to produce and their impact on mark-recapture estimates.
Potential Forensic applications.
Footprints are basically cryptic ground evidence, part of a field of interest in security, forensic and military field. FIT is able to identify individual animal footprints from their geometry, and the same technique might be applied to assist in the automation of certain forensic procedures which currently require ‘expert’ opinion to classify at the final decision boundary. Human fingerprinting, ballistics work, and trace evidences could all be investigated further using an adapted FIT.
Environmental Impact Assessments (EIA)
The EIA is a necessary prologue to any large-scale construction project which might negatively impact on a natural ecosystem. The identification of species which leave footprints in this environment can provide data on individuals and populations before, during and after the project.