Alien plant threatens Nile crocodile (Crocodylus niloticus) breeding in Lake St. Lucia, South Africa
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Published source details
Leslie A.J. & Spotila J.R. (2001) Alien plant threatens Nile crocodile (Crocodylus niloticus) breeding in Lake St. Lucia, South Africa. Biological Conservation, 98, 347-355.
Published source details Leslie A.J. & Spotila J.R. (2001) Alien plant threatens Nile crocodile (Crocodylus niloticus) breeding in Lake St. Lucia, South Africa. Biological Conservation, 98, 347-355.
Actions
This study is summarised as evidence for the following.
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Manage vegetation by hand (selective weeding) Action Link |
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Remove or control non-native/invasive plants Action Link |
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Manage vegetation by hand (selective weeding)
A replicated, controlled, before-and-after study in 1993–1997 in shoreline habitat on a lake in Kwazulu-Natal, South Africa (Leslie & Spotila 2001) found that removing the invasive plant Chromolaena odorata from nesting sites by hand increased Nile crocodile Crocodylus niloticus successful nesting attempts over three breeding seasons. Results were not statistically tested. Known nesting sites where invasive vegetation was removed had 40% (2 out of 5 sites nested), 80% and 60% success over three breeding seasons following removal, compared to 40% nesting success before removal. Newly created nesting sites, where invasive vegetation was completely removed, had 33% (2 out of 6 sites nested), 33% and 67% success over three breeding seasons following removal, compared to 0% success before removal. Nesting success in sites where invasive vegetation was not removed was 100% (5 out of 5 sites nested), 60%, 40% and 40% over four breeding seasons. In 1993, sixteen nest sites were chosen: five known nesting sites where the invasive plant was present and manually removed from 1994; six sites newly created by manually removing all invasive vegetation and root stock (4 x 4 m area); and five where the invasive plant was present and was not removed. In 1994–1997 (three breeding seasons) invasive vegetation clearing was carried out each season. In 1993–1997, all sites were monitored using foot, boat and aerial surveys in mid-December to determine use of nesting sites.
(Summarised by: Maggie Watson)
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Remove or control non-native/invasive plants
A replicated, controlled, before-and-after study in 1993–1997 in shoreline habitat on a lake in Kwazulu-Natal, South Africa (Leslie & Spotila 2001) found that manual removal of the invasive plant Chromolaena odorata from nesting sites increased Nile crocodile Crocodylus niloticus successful nesting attempts over three breeding seasons. Results were not statistically tested. Known nesting sites where invasive vegetation was removed had 40% (2 out of 5 sites nested), 80% and 60% success over three breeding seasons following removal, compared to 40% nesting success before removal. Newly created nesting sites, where invasive vegetation was completely removed, had 33% (2 out of 6 sites nested), 33% and 67% success over three breeding seasons following removal, compared to 0% success before removal. Nesting success in sites where invasive vegetation was not removed was 100% (5 out of 5 sites nested), 60%, 40% and 40% over four breeding seasons. In 1993, sixteen nest sites were chosen: five known nesting sites where the invasive plant was present and manually removed from 1994; six sites newly created by manually clearing of all invasive vegetation and root stock (4 x 4 m area); and five where the invasive plant was present and was left untreated. In 1994–1997 (three breeding seasons) invasive vegetation clearing was carried out each season. In 1993–1997, all sites were monitored using foot, boat and aerial surveys in mid-December to determine use of nesting sites.
(Summarised by: Maggie Watson, William Morgan)
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