An 11-digit identification system for individual Nile crocodiles using natural markings
Research and conservation of wild crocodiles and husbandry of captive crocodiles requires the reliable identification of individuals. We present a method using the individual colour markings on the first 10 single-crest scutes on the tails of Nile crocodiles (Crocodylus niloticus). The scutes are sc...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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AOSIS
2016-05-01
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| Series: | Koedoe: African Protected Area Conservation and Science |
| Subjects: | |
| Online Access: | https://koedoe.co.za/index.php/koedoe/article/view/1351 |
| _version_ | 1818893841194811392 |
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| author | Hindrik Bouwman Enrico Cronje |
| author_facet | Hindrik Bouwman Enrico Cronje |
| author_sort | Hindrik Bouwman |
| collection | DOAJ |
| description | Research and conservation of wild crocodiles and husbandry of captive crocodiles requires the reliable identification of individuals. We present a method using the individual colour markings on the first 10 single-crest scutes on the tails of Nile crocodiles (Crocodylus niloticus). The scutes are scored by number for colour, with a prefix for left or right providing a binary 11-digit identification number (identification numbers [IDs]; e.g. 12232232242 and 22333233232) per crocodile. A survey of 359 captive Nile crocodiles showed no duplication. However, 42% had asymmetrical scute markings requiring a binary approach. There does not seem to be a change in patterns with age, except that the number of missing scutes increased. A small trial showed that this method can be applied in the field, although more work is needed to determine observer bias and establish parameters for observability in the field. It is unlikely that both left and right IDs would be obtainable for each individual, but other distinctive markings such as scute shape and damage can be used to register the two IDs to one individual. Having two independent IDs for each crocodile provides the possibility of two independent population estimates for equal effort without having to link left and right IDs to individuals. Our proposed method would be useful in conservation, individual tracking and husbandry.
Conservation implications: A non-invasive marking and recapture method for Nile crocodile is presented whereby the first 10 single-crest scutes are scored for colour, allowing conservation practitioners to count and monitor crocodile populations and individuals. This method provides two equal-effort estimations of population size, as left and right hand sides are scored independently.
Keywords: Crocodylus niloticus; identification; mark - recapture; mark - resight |
| first_indexed | 2024-12-19T18:19:00Z |
| format | Article |
| id | doaj.art-8e2768c0a0a64c6f93293a1824cd5005 |
| institution | Directory Open Access Journal |
| issn | 0075-6458 2071-0771 |
| language | English |
| last_indexed | 2024-12-19T18:19:00Z |
| publishDate | 2016-05-01 |
| publisher | AOSIS |
| record_format | Article |
| series | Koedoe: African Protected Area Conservation and Science |
| spelling | doaj.art-8e2768c0a0a64c6f93293a1824cd50052022-12-21T20:11:02ZengAOSISKoedoe: African Protected Area Conservation and Science0075-64582071-07712016-05-01581e1e610.4102/koedoe.v58i1.13511127An 11-digit identification system for individual Nile crocodiles using natural markingsHindrik Bouwman0Enrico Cronje1Unit for Environmental Sciences and Management, North-West University, Potchefstroom CampusUnit for Environmental Sciences and Management, North-West University, Potchefstroom CampusResearch and conservation of wild crocodiles and husbandry of captive crocodiles requires the reliable identification of individuals. We present a method using the individual colour markings on the first 10 single-crest scutes on the tails of Nile crocodiles (Crocodylus niloticus). The scutes are scored by number for colour, with a prefix for left or right providing a binary 11-digit identification number (identification numbers [IDs]; e.g. 12232232242 and 22333233232) per crocodile. A survey of 359 captive Nile crocodiles showed no duplication. However, 42% had asymmetrical scute markings requiring a binary approach. There does not seem to be a change in patterns with age, except that the number of missing scutes increased. A small trial showed that this method can be applied in the field, although more work is needed to determine observer bias and establish parameters for observability in the field. It is unlikely that both left and right IDs would be obtainable for each individual, but other distinctive markings such as scute shape and damage can be used to register the two IDs to one individual. Having two independent IDs for each crocodile provides the possibility of two independent population estimates for equal effort without having to link left and right IDs to individuals. Our proposed method would be useful in conservation, individual tracking and husbandry. Conservation implications: A non-invasive marking and recapture method for Nile crocodile is presented whereby the first 10 single-crest scutes are scored for colour, allowing conservation practitioners to count and monitor crocodile populations and individuals. This method provides two equal-effort estimations of population size, as left and right hand sides are scored independently. Keywords: Crocodylus niloticus; identification; mark - recapture; mark - resighthttps://koedoe.co.za/index.php/koedoe/article/view/1351Crocodylus niloticusidentificationmark - recapturemark - resight |
| spellingShingle | Hindrik Bouwman Enrico Cronje An 11-digit identification system for individual Nile crocodiles using natural markings Koedoe: African Protected Area Conservation and Science Crocodylus niloticus identification mark - recapture mark - resight |
| title | An 11-digit identification system for individual Nile crocodiles using natural markings |
| title_full | An 11-digit identification system for individual Nile crocodiles using natural markings |
| title_fullStr | An 11-digit identification system for individual Nile crocodiles using natural markings |
| title_full_unstemmed | An 11-digit identification system for individual Nile crocodiles using natural markings |
| title_short | An 11-digit identification system for individual Nile crocodiles using natural markings |
| title_sort | 11 digit identification system for individual nile crocodiles using natural markings |
| topic | Crocodylus niloticus identification mark - recapture mark - resight |
| url | https://koedoe.co.za/index.php/koedoe/article/view/1351 |
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