resightings

Resightings refer to the repeated observation of an individual that has been previously seen. In ecology and conservation biology, resighting data are collected when a marked, tagged, or otherwise identifiable animal is seen again during subsequent surveys or encounters. This information complements initial capture or sighting records and is central to understanding life-history traits beyond a single observation.

Resightings are obtained through various methods, including physical tagging (bands, flipper tags, ear tags, PIT tags), active tagging programs, photo-identification of unique markings, and data from automated systems such as camera traps or GPS transmitters. Each resighting provides a data point indicating that the individual is alive and located within a particular area, or following a known movement path.

Analytically, resighting data are used in mark-recapture and mark-resight models to estimate population parameters such as survival rates, population size, and movement or migration patterns. These models separate the probability of detecting an individual from the probability of its presence, allowing researchers to infer life-history processes from imperfectly observed data.

Interpreting resightings requires consideration of potential biases, including misidentification, tag loss, variations in observer effort, and unequal detection across time or space. Resightings can indicate site fidelity and longevity but may also reflect temporary absence or dispersal rather than mortality.

Resightings are widely employed in wildlife research and management to monitor populations, assess conservation status, and evaluate the effectiveness of tagging methods and protection measures. See also mark-recapture, photo-identification, and population dynamics.