Ontogenetic shifts in the nesting behaviour of female crocodiles

Cameron J. Baker, Craig E. Franklin, Hamish A. Campbell, Terri R. Irwin, Ross G. Dwyer

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Body size and age are crucial factors influencing reproductive capacity and success. As females grow, their reproductive investment and success often increase due to improved overall physiological condition and experience gained through successive reproductive events. While much of this work has been conducted on birds and mammals, surprisingly little is known on how body size affects nesting decisions in other long-lived vertebrates. We monitored the movements and nesting behaviour of 57 wild female estuarine crocodiles Crocodylus porosus over a 10-year period (and across consecutive nesting seasons) using externally mounted satellite tags, implanted acoustic transmitters and a network of submerged acoustic receivers. Applying Hidden Markov models to the telemetry-derived location data revealed that female nesting behaviours could be split into three distinct states: (i) ranging movements within home ranges and at nesting sites; (ii) migrations to and from nesting sites; (iii) and nesting/nest guarding. We found that during migration events, larger females migrated further and remained away from dry season territories for longer periods than smaller individuals. Furthermore, not only were migratory movements stimulated by increases in rainfall, larger females migrated to nest sites at lower rainfall thresholds than smaller females. We provide some of the first evidence of body size influencing nesting decisions in an ectothermic vertebrate, with shifts likely resulting from an increased willingness to invest in nest protection among larger and more experienced females.

Original languageEnglish
Pages (from-to)891-904
Number of pages14
JournalOecologia
Volume189
Issue number4
Early online date13 Mar 2019
DOIs
Publication statusPublished - Apr 2019

Fingerprint

nesting behavior
crocodiles
body size
Crocodylus porosus
nesting sites
vertebrate
acoustics
nest guarding
female behavior
vertebrates
nests
rainfall
rain
nest site
telemetry
home range
crocodile
dry season
nest
mammal

Cite this

Baker, C. J., Franklin, C. E., Campbell, H. A., Irwin, T. R., & Dwyer, R. G. (2019). Ontogenetic shifts in the nesting behaviour of female crocodiles. Oecologia, 189(4), 891-904. https://doi.org/10.1007/s00442-019-04382-4
Baker, Cameron J. ; Franklin, Craig E. ; Campbell, Hamish A. ; Irwin, Terri R. ; Dwyer, Ross G. / Ontogenetic shifts in the nesting behaviour of female crocodiles. In: Oecologia. 2019 ; Vol. 189, No. 4. pp. 891-904.
@article{8e455da6ed5b48ccb48cdd3cce7daaaa,
title = "Ontogenetic shifts in the nesting behaviour of female crocodiles",
abstract = "Body size and age are crucial factors influencing reproductive capacity and success. As females grow, their reproductive investment and success often increase due to improved overall physiological condition and experience gained through successive reproductive events. While much of this work has been conducted on birds and mammals, surprisingly little is known on how body size affects nesting decisions in other long-lived vertebrates. We monitored the movements and nesting behaviour of 57 wild female estuarine crocodiles Crocodylus porosus over a 10-year period (and across consecutive nesting seasons) using externally mounted satellite tags, implanted acoustic transmitters and a network of submerged acoustic receivers. Applying Hidden Markov models to the telemetry-derived location data revealed that female nesting behaviours could be split into three distinct states: (i) ranging movements within home ranges and at nesting sites; (ii) migrations to and from nesting sites; (iii) and nesting/nest guarding. We found that during migration events, larger females migrated further and remained away from dry season territories for longer periods than smaller individuals. Furthermore, not only were migratory movements stimulated by increases in rainfall, larger females migrated to nest sites at lower rainfall thresholds than smaller females. We provide some of the first evidence of body size influencing nesting decisions in an ectothermic vertebrate, with shifts likely resulting from an increased willingness to invest in nest protection among larger and more experienced females.",
keywords = "Estuarine crocodile, Hidden Markov modelling, Nest-site selection, Parental investment, Telemetry",
author = "Baker, {Cameron J.} and Franklin, {Craig E.} and Campbell, {Hamish A.} and Irwin, {Terri R.} and Dwyer, {Ross G.}",
year = "2019",
month = "4",
doi = "10.1007/s00442-019-04382-4",
language = "English",
volume = "189",
pages = "891--904",
journal = "Oecologia",
issn = "0029-8549",
publisher = "Springer-Verlag London Ltd.",
number = "4",

}

Baker, CJ, Franklin, CE, Campbell, HA, Irwin, TR & Dwyer, RG 2019, 'Ontogenetic shifts in the nesting behaviour of female crocodiles', Oecologia, vol. 189, no. 4, pp. 891-904. https://doi.org/10.1007/s00442-019-04382-4

Ontogenetic shifts in the nesting behaviour of female crocodiles. / Baker, Cameron J.; Franklin, Craig E.; Campbell, Hamish A.; Irwin, Terri R.; Dwyer, Ross G.

In: Oecologia, Vol. 189, No. 4, 04.2019, p. 891-904.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Ontogenetic shifts in the nesting behaviour of female crocodiles

AU - Baker, Cameron J.

AU - Franklin, Craig E.

AU - Campbell, Hamish A.

AU - Irwin, Terri R.

AU - Dwyer, Ross G.

PY - 2019/4

Y1 - 2019/4

N2 - Body size and age are crucial factors influencing reproductive capacity and success. As females grow, their reproductive investment and success often increase due to improved overall physiological condition and experience gained through successive reproductive events. While much of this work has been conducted on birds and mammals, surprisingly little is known on how body size affects nesting decisions in other long-lived vertebrates. We monitored the movements and nesting behaviour of 57 wild female estuarine crocodiles Crocodylus porosus over a 10-year period (and across consecutive nesting seasons) using externally mounted satellite tags, implanted acoustic transmitters and a network of submerged acoustic receivers. Applying Hidden Markov models to the telemetry-derived location data revealed that female nesting behaviours could be split into three distinct states: (i) ranging movements within home ranges and at nesting sites; (ii) migrations to and from nesting sites; (iii) and nesting/nest guarding. We found that during migration events, larger females migrated further and remained away from dry season territories for longer periods than smaller individuals. Furthermore, not only were migratory movements stimulated by increases in rainfall, larger females migrated to nest sites at lower rainfall thresholds than smaller females. We provide some of the first evidence of body size influencing nesting decisions in an ectothermic vertebrate, with shifts likely resulting from an increased willingness to invest in nest protection among larger and more experienced females.

AB - Body size and age are crucial factors influencing reproductive capacity and success. As females grow, their reproductive investment and success often increase due to improved overall physiological condition and experience gained through successive reproductive events. While much of this work has been conducted on birds and mammals, surprisingly little is known on how body size affects nesting decisions in other long-lived vertebrates. We monitored the movements and nesting behaviour of 57 wild female estuarine crocodiles Crocodylus porosus over a 10-year period (and across consecutive nesting seasons) using externally mounted satellite tags, implanted acoustic transmitters and a network of submerged acoustic receivers. Applying Hidden Markov models to the telemetry-derived location data revealed that female nesting behaviours could be split into three distinct states: (i) ranging movements within home ranges and at nesting sites; (ii) migrations to and from nesting sites; (iii) and nesting/nest guarding. We found that during migration events, larger females migrated further and remained away from dry season territories for longer periods than smaller individuals. Furthermore, not only were migratory movements stimulated by increases in rainfall, larger females migrated to nest sites at lower rainfall thresholds than smaller females. We provide some of the first evidence of body size influencing nesting decisions in an ectothermic vertebrate, with shifts likely resulting from an increased willingness to invest in nest protection among larger and more experienced females.

KW - Estuarine crocodile

KW - Hidden Markov modelling

KW - Nest-site selection

KW - Parental investment

KW - Telemetry

UR - http://www.scopus.com/inward/record.url?scp=85062992976&partnerID=8YFLogxK

U2 - 10.1007/s00442-019-04382-4

DO - 10.1007/s00442-019-04382-4

M3 - Article

VL - 189

SP - 891

EP - 904

JO - Oecologia

JF - Oecologia

SN - 0029-8549

IS - 4

ER -