Estimating demographic parameters for capture–recapture data in the presence of multiple mark types

Smout, Sophie; King, Ruth; Pomeroy, Patrick P.

doi:10.1007/s10651-010-0135-y

Cited by 29 publications

(45 citation statements)

References 32 publications

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“…In addition, analyses should not assume mark loss is constant over all ages or by sex. If double tags are to be the primary method for identifying individuals, it is important to test the assumption of independent tag loss by employing at least two forms of unique identification on at least a subset of the sampled population (Juillet et al 2011, Smout et al 2011a. No mark types need to be permanent as long as the different types are lost independently of each other.…”

Section: Discussionmentioning

confidence: 99%

The implications of assuming independent tag loss in southern elephant seals

et al. 2012

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Abstract. Survival and reproductive rate estimation requires following uniquely identified individuals through time, and many statistical models assume markings used to identify individuals are permanent. However, survival rates are underestimated when single marks are lost, since the models will effectively score those animals as dead. In order to account for mark loss, some researchers use a double-mark approach, assuming the probability of losing one mark is independent of losing the other one. Therefore, mark loss can be estimated using animals that have lost one mark. Using a 17-year dataset of southern elephant seals (Mirounga leonina) marked with permanent brands and two cattle tags in their hind flippers, we were able to compare tag loss and survival rate estimates with and without the assumption of independent tag loss with respect to age, sex, and wean mass. We demonstrate the assumption of independent tag loss is not valid, showing it is more likely for an animal to lose both tags than just one or the other. The assumption of independent tag loss leads to an underestimate of survival rates which in turn leads to underestimates of population growth rate. In addition, tag loss rates are different by sex and age, with older males more likely to lose tags. Tag loss is also a quadratic function of wean mass through age two, with smaller and larger animals more likely to lose both tags. Such differences are possibly due to differences in behavior, flipper growth, and immune response. Using a Bayesian approach, we will be able to use our tag loss estimates as priors in future analyses for a subset of marked animals that only have flipper tags. With this population, the independent tag loss models are more likely to incorrectly estimate a declining population (growth rate , 1.0), potentially leading to unwarranted management action. To account for non-independent mark loss in survival rate studies, we recommend researchers use at least two forms of marking on at least a subset of animals. However, neither form of marking need be permanent as long as mark loss is independent between the different forms.

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Section: Discussionmentioning

confidence: 99%

The implications of assuming independent tag loss in southern elephant seals

et al. 2012

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“…It is also well known that the MRR based mobility estimates tend to substantially underestimate long distance movements of studied organisms (e.g. Smout et al, 2010;Drag et al, 2011;Pe'Er et al, 2013). We may thus expect that the beetles are able to reach habitat patches kilometers away from an occupied patch as long as no migration barriers such as e.g.…”

Section: Dispersal Optionsmentioning

confidence: 99%

Dispersal of individuals of the flightless grassland ground beetle, Carabus hungaricus (Coleoptera: Carabidae), in three populations and what they tell us about mobility estimates based on mark-recapture

Elek¹,

Drag²,

Pokluda³

et al. 2014

Eur. J. Entomol.

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Abstract. Knowledge of the dispersal ability of endangered species is crucial for developing effective, evidence-based conservation policies. Due to their limited dispersal abilities and specific habitat requirements, insects are among the animals most threatened by habitat fragmentation. We studied three populations of the highly endangered species of ground beetle, Carabus hungaricus, at three sites in Central Europe (Hungary and Czech Republic) using mark-release-recapture (MRR). The total catch of 574 pitfall traps set at the three sites was 6255 individuals. Depending on the site, the percentage recaptured was 13-32%. average and maximum distance moved by individuals of both sexes at each of the sites ranged between 47-132 and 207-1104 m, respectively. The probability of the movements following an inverse power function (IPF) for the two sexes did not differ, but did differ among sites. Probability of dispersing for distances >100 m differed by an order of magnitude between sites, most likely because of differences in how the samples were collected. Despite the fact that individual beetles are able to move over distances in the order of kilometres, the high fragmentation of their habitats is likely to prevent them from colonizing most uninhabited habitat patches. Therefore, the conservation of this threatened ground beetle could be improved by adopting and implementing a policy of assisted dispersal. our results from three study sites also provide an interesting illustration of the variability in the estimates of the probability of dispersal obtained using MRR.* Deceased.

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“…Seal population trajectories are assessed using (manned) synoptic aerial surveys of seals at breeding for gray seals and molt for harbor seals to provide data to inform population models (Lonergan et al 2007;SCOS 2013). In parallel, individual-based studies of life history provide estimates of vital rates for the population models (Smout et al 2011;Cordes and Thompson 2014). Collecting life history information for population parameters requires longterm detailed information on individuals, currently provided by direct observations on animals known from flipper tagging, but also using photo-ID of natural pelage patterns (Hiby et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Assessing use of and reaction to unmanned aerial systems in gray and harbor seals during breeding and molt in the UK

Pomeroy

O’Connor

Davies³

2015

J. Unmanned Veh. Sys.

117

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Wildlife biology applications of unmanned aerial systems (UAS) are extensive. Survey, identification, and measurement using UAS equipped with appropriate sensors can now be added to the suite of techniques available for monitoring animals -here we detail our experiences in using UAS to obtain detailed information from groups of seals, which can be difficult to observe from land. Trial flights to survey gray and harbor seals using a range of different platforms and imaging systems have been carried out with varying success at a number of sites in Scotland over the last two years. The best performing UAS system was determined by site, field situation, and the data required. Our systems routinely allow relative abundance, species, age-class, and individual identity to be obtained from images currently, with measures of body size also obtainable but open to refinement. However, the impacts of UAS on target species can also be variable and should be monitored closely. We found variable responses to UAS flights, possibly related to the animals' experience of previous disturbance.Key words: UAS, wildlife, seals, photo-ID, photogrammetry, behaviour.Résumé : L'utilisation des systèmes aériens sans pilote (UAS) en biologie faunique ne cesse d'augmenter. Les levés, l'identification et les mesures utilisant les UAS munis de capteurs appropriés font maintenant partie de l'ensemble des techniques disponibles pour surveiller les animaux -ici, nous exposons en détail nos expériences d'utilisation des UAS pour obtenir des informations détaillées sur des groupes de phoques, qui peuvent être difficiles à observer à partir de la terre. Des vols d'essais pour faire le levé des phoques gris et communs utilisant une gamme de plateformes et de systèmes d'imagerie ont été réalisés avec un niveau de succès varié à un nombre de sites en Écosse au cours de deux dernières années. On a déterminé l'UAS le plus performant selon le site, la situation sur le terrain et les données requises. Nos systèmes permettent de couramment obtenir l'abondance relative, les espèces, la classe d'âge et l'identité particulière à partir d'images, y compris les mesures de la masse corporelle mais pouvant être perfectionnées. Cependant, les effets des UAS sur les espèces ciblées peuvent varier et doivent être surveillés de près. Nous avons trouvé des réactions variées aux vols d'UAS, probablement lié à l'expérience des animaux suite à des perturbations antérieures.Mots-clés : système aérien sans pilote (UAS), faune, phoques, photo-identificateur, photogrammétrie, comportement.

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Estimating demographic parameters for capture–recapture data in the presence of multiple mark types

Cited by 29 publications

References 32 publications

The implications of assuming independent tag loss in southern elephant seals

The implications of assuming independent tag loss in southern elephant seals

Dispersal of individuals of the flightless grassland ground beetle, Carabus hungaricus (Coleoptera: Carabidae), in three populations and what they tell us about mobility estimates based on mark-recapture

Assessing use of and reaction to unmanned aerial systems in gray and harbor seals during breeding and molt in the UK

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