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Spatial and Temporal Variation in Reproduction of a Generalist Crocodilian, Caiman crocodilus yacare, in a Seasonally Flooded Wetland.

Campos Z, Mourão G, Coutinho M, Magnusson WE, Soriano BM - PLoS ONE (2015)

Bottom Line: Most of the variation in number of nests could not be predicted by the environmental variables, but could be represented mathematically by a sine wave.Presently, ranches are used as management units under the legislation for ranching Pantanal caimans.However, although some breeding females were recaptured in the area after periods of up to 21 years, most were not recaptured near nests or in general surveys of the area, suggesting that females are not strongly philopatric and that ranches do not represent isolated demographic units.

View Article: PubMed Central - PubMed

Affiliation: Embrapa Pantanal, Corumbá, Mato Grosso do Sul, Brazil.

ABSTRACT
We monitored the number of caiman (Caiman crocodilus yacare) nests in two ranches in the Brazilian Pantanal that cover an area of about 50.000 ha for 28 years (1987-2014). The number of nests was related to combinations of rainfall, water level, and number of days with temperature below 20°C, depending on the area. Most of the variation in number of nests could not be predicted by the environmental variables, but could be represented mathematically by a sine wave. We were not able to identify any external driver and suspect that the regular fluctuations may have resulted from an intrinsic population process. Presently, ranches are used as management units under the legislation for ranching Pantanal caimans. However, although some breeding females were recaptured in the area after periods of up to 21 years, most were not recaptured near nests or in general surveys of the area, suggesting that females are not strongly philopatric and that ranches do not represent isolated demographic units.

No MeSH data available.


Related in: MedlinePlus

Autocorrelation in number of nests of Caiman crocodilus yacare on Nhumirim Ranch for lag intervals up to 20 years.
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pone.0129368.g004: Autocorrelation in number of nests of Caiman crocodilus yacare on Nhumirim Ranch for lag intervals up to 20 years.

Mentions: All variables measured showed autocorrelation at some lag interval (Permutation test for Moran´s I: P<0.05 in all cases). The lagged autocorrelations of number of nests on Nhumirim Ranch were not serially random (Serial Randomness test: C20 = 0.71, P = 0.0005), but there was no significant deviation from serial randomness for lagged autocorrelations of number of nests on Campo Dora Ranch (Serial Randomness test: C20<0.001, P>0.25). The pattern of autocorrelation for number of nests on Nhumirim Ranch indicated a probable cyclical pattern with a periodicity of about 9 years (Fig 4). Based on this result, the process causing the autocorrelation was modeled using a sine wave with periodicity of 9 years, and this model closely mirrored the major fluctuations in the number of nests on Nhumirim Ranch (Fig 3A).


Spatial and Temporal Variation in Reproduction of a Generalist Crocodilian, Caiman crocodilus yacare, in a Seasonally Flooded Wetland.

Campos Z, Mourão G, Coutinho M, Magnusson WE, Soriano BM - PLoS ONE (2015)

Autocorrelation in number of nests of Caiman crocodilus yacare on Nhumirim Ranch for lag intervals up to 20 years.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4481102&req=5

pone.0129368.g004: Autocorrelation in number of nests of Caiman crocodilus yacare on Nhumirim Ranch for lag intervals up to 20 years.
Mentions: All variables measured showed autocorrelation at some lag interval (Permutation test for Moran´s I: P<0.05 in all cases). The lagged autocorrelations of number of nests on Nhumirim Ranch were not serially random (Serial Randomness test: C20 = 0.71, P = 0.0005), but there was no significant deviation from serial randomness for lagged autocorrelations of number of nests on Campo Dora Ranch (Serial Randomness test: C20<0.001, P>0.25). The pattern of autocorrelation for number of nests on Nhumirim Ranch indicated a probable cyclical pattern with a periodicity of about 9 years (Fig 4). Based on this result, the process causing the autocorrelation was modeled using a sine wave with periodicity of 9 years, and this model closely mirrored the major fluctuations in the number of nests on Nhumirim Ranch (Fig 3A).

Bottom Line: Most of the variation in number of nests could not be predicted by the environmental variables, but could be represented mathematically by a sine wave.Presently, ranches are used as management units under the legislation for ranching Pantanal caimans.However, although some breeding females were recaptured in the area after periods of up to 21 years, most were not recaptured near nests or in general surveys of the area, suggesting that females are not strongly philopatric and that ranches do not represent isolated demographic units.

View Article: PubMed Central - PubMed

Affiliation: Embrapa Pantanal, Corumbá, Mato Grosso do Sul, Brazil.

ABSTRACT
We monitored the number of caiman (Caiman crocodilus yacare) nests in two ranches in the Brazilian Pantanal that cover an area of about 50.000 ha for 28 years (1987-2014). The number of nests was related to combinations of rainfall, water level, and number of days with temperature below 20°C, depending on the area. Most of the variation in number of nests could not be predicted by the environmental variables, but could be represented mathematically by a sine wave. We were not able to identify any external driver and suspect that the regular fluctuations may have resulted from an intrinsic population process. Presently, ranches are used as management units under the legislation for ranching Pantanal caimans. However, although some breeding females were recaptured in the area after periods of up to 21 years, most were not recaptured near nests or in general surveys of the area, suggesting that females are not strongly philopatric and that ranches do not represent isolated demographic units.

No MeSH data available.


Related in: MedlinePlus