Photo‐Identification of Sea Otters Using Nose Scars

Abstract

We evaluated the use of naturally occurring nose scars to identify individual sea otters (Enhydra lutris) in Simpson Bay, Prince William Sound, Alaska, USA. We spent 520 hours over 103 days conducting photo‐identification surveys from June to August 2002 and 2003. Altogether, we identified 114 individuals. The number of sightings per individual ranged from 1 to 26, with an average of 3.3. The maximum number of sightings of an individual within a single year was 19. We saw 54 otters (47%)on >1 day, with an average of 8.1 sightings per individual for those seen more than once. We identified 8 individuals (19% of those identified in 2002) in both years. Males and otters of undetermined sex that we first sighted in June had the highest re‐sighting rates. We considered 45% of all individuals encountered identifiable from nose scars. Nose scars were present in 63% (n = 19) of males, 45% (n = 45) of females, and 40% (n = 49) of otters of undetermined sex. Our results are similar to the results of photo‐identification studies of other marine mammals, suggesting that this technique may be a useful tool for the individual identification of sea otters as well.

Sex-Specific Patterns in Abundance, Temporary Emigration and Survival of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in Coastal and Estuarine Waters

“…The results derived from datasets using 3 years (2007( -2009( , Smith et al, 2013 . Variations in abundance among seasons and years could be a reflection of both intrinsic (dolphin biology and social dynamics) and extrinsic factors (environmental factors and prey availability).…”

“…Capture-recapture techniques for estimating various population parameters include physical tagging (Baker, 2004), genetic tagging (Palsbøll et al, 1997) or photographic identification (photo-ID) of individuals through their natural markings (Würsig and Jefferson, 1990;Hammond, 2009), including pigmentation patterns (Arzoumanian et al, 2005), pelage marks (Hastings et al, 2008), scars (Gilkinson et al, 2007), and whisker patterns (Anderson et al, 2010). Photo-ID has been widely used across taxonomic groups, such as terrestrial and marine mammals (Kelly, 2001;Langtimm et al, 2004), reptiles (Schofield et al, 2008;Gardiner et al, 2014) and fish (Couturier et al, 2014;Kanive et al, 2015).…”

Estima de la población de nutria en las Tablas de Daimiel mediante captura-recaptura espacial y muestreo de distancias

“…Asimismo se ha descrito la metodología del fototrampeo para la detección de la especie (Jones & Raphael 1993). Aunque se ha descrito una metodología de identificación individual para la nutria marina (Enhydra lutris Linnaeus, 1758) basada en marcas nasales (Gilkinson et al 2007), en el caso que nos ocupa era muy difícil abordar la captura-recaptura mediante fototrampeo con identificación individual por la práctica ausencia de marcas naturales fácilmente reconocibles en las fotografías, como han puesto de manifiesto Macdonald & Harrington (2012).…”

Field identification of individual White-headed VulturesTrigonoceps occipitalisusing plumage patterns - an information theoretic approach

“…These methods often utilize variation in natural markings on the animal such as skin patterns, scars and fur or plumage patterns (Pennycuick & Rudnai 1970, Bretagnolle et al 1994, Arroyo & Bretagnolle 1999, Anderson et al 2007, Gilkinson et al 2007) as well as vocalizations (Blumstein & Munos 2005, Pollard et al 2010. Natural markings are used less frequently because not all species have suitable features, or there is insufficient feature variation between individuals for the purposes of accurate identification.…”