A new approach to estimate fecundity rate from inter-birth intervals

Mònica Arso Civil; Barbara Cheney; Nicola J. Quick; Paul M. Thompson; Philip S. Hammond

doi:10.1002/ecs2.1796

A new approach to estimate fecundity rate from inter-birth intervals

Mònica Arso Civil (Corresponding Author), Barbara Cheney, Nicola J. Quick, Paul M. Thompson, Philip S. Hammond

University of St Andrews

Research output: Contribution to journal › Article › peer-review

21 Citations (Scopus)

15 Downloads (Pure)

Abstract

Accurate estimates of fecundity rate are key to population assessments and effectively direct conservation efforts. We present a new approach to estimate fecundity rate based on the probability of a female giving birth, conditional on a previous birth t years ago, from which an expected inter-birth interval (IBI) can be estimated. We use generalized linear mixed-effects models to account for individual and temporal variability and apply the approach to individual reproductive histories of bottlenose dolphins (Tursiops truncatus) from the east coast of Scotland. We estimate a fecundity rate of 0.222 (95% CI = 0.218–0.253) and an expected IBI of 4.49 yr (95% CI = 3.94–4.93 yr). We use simulated data samples to show that the approach produces estimates with a minimum bias of <3%. Simulations are also used to investigate the effect of the most common data-driven biases in the estimates of birth intervals and fecundity rate; we recommend longitudinal studies of at least 10 yr and capture probabilities of at least 0.3 when using this methodology. The approach may be modified to incorporate other parameters of interest and should be applicable to any population with comprehensive data on birth intervals.

Original language	English
Article number	e01796
Journal	Ecosphere
Volume	8
Issue number	4
Early online date	18 Apr 2017
DOIs	https://doi.org/10.1002/ecs2.1796
Publication status	Published - Apr 2017

Bibliographical note

Funded by
Department of Energy and Climate Change (UK), BES, ASAB, Greenpeace, Environmental Trust, Scottish Natural Heritage, Scottish Government, Whale and Dolphin Conservation, Talisman Energy (UK) Ltd., DECC, Chevron, Natural Environment Research Council

Acknowledgments
Funding for this work was provided by the Department of Energy and Climate Change (UK). Photo-identification data were collected during a series of grants and contracts from the BES, ASAB, Greenpeace Environmental Trust, Scottish Natural Heritage, Scottish Government, Whale and Dolphin Conservation, Talisman Energy (UK) Ltd., DECC, Chevron, and the Natural Environment Research Council. All survey work was carried out under Scottish Natural Heritage Animal Scientific Licences. The authors have no conflict of interest to declare. We thank Mark Bravington for his helpful advice at the early stages of this work and two anonymous reviewers for their useful comments on the manuscript.

Keywords

birth interval
birth probability
bottlenose dolphin
cetaceans
fecundity
generalized linear mixed models
mark-recapture data

Access to Document

10.1002/ecs2.1796Licence: CC BY

A new approach to estimate fecundity rate from inter-birth intervals
© 2017 Arso Civil et al. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. https://creativecommons.org/licenses/by/4.0/
Final published version, 714 KBLicence: CC BY

Cite this

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abstract = "Accurate estimates of fecundity rate are key to population assessments and effectively direct conservation efforts. We present a new approach to estimate fecundity rate based on the probability of a female giving birth, conditional on a previous birth t years ago, from which an expected inter-birth interval (IBI) can be estimated. We use generalized linear mixed-effects models to account for individual and temporal variability and apply the approach to individual reproductive histories of bottlenose dolphins (Tursiops truncatus) from the east coast of Scotland. We estimate a fecundity rate of 0.222 (95% CI = 0.218–0.253) and an expected IBI of 4.49 yr (95% CI = 3.94–4.93 yr). We use simulated data samples to show that the approach produces estimates with a minimum bias of <3%. Simulations are also used to investigate the effect of the most common data-driven biases in the estimates of birth intervals and fecundity rate; we recommend longitudinal studies of at least 10 yr and capture probabilities of at least 0.3 when using this methodology. The approach may be modified to incorporate other parameters of interest and should be applicable to any population with comprehensive data on birth intervals.",

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note = "Funded by Department of Energy and Climate Change (UK), BES, ASAB, Greenpeace, Environmental Trust, Scottish Natural Heritage, Scottish Government, Whale and Dolphin Conservation, Talisman Energy (UK) Ltd., DECC, Chevron, Natural Environment Research Council Acknowledgments Funding for this work was provided by the Department of Energy and Climate Change (UK). Photo-identification data were collected during a series of grants and contracts from the BES, ASAB, Greenpeace Environmental Trust, Scottish Natural Heritage, Scottish Government, Whale and Dolphin Conservation, Talisman Energy (UK) Ltd., DECC, Chevron, and the Natural Environment Research Council. All survey work was carried out under Scottish Natural Heritage Animal Scientific Licences. The authors have no conflict of interest to declare. We thank Mark Bravington for his helpful advice at the early stages of this work and two anonymous reviewers for their useful comments on the manuscript.",

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N1 - Funded by Department of Energy and Climate Change (UK), BES, ASAB, Greenpeace, Environmental Trust, Scottish Natural Heritage, Scottish Government, Whale and Dolphin Conservation, Talisman Energy (UK) Ltd., DECC, Chevron, Natural Environment Research Council Acknowledgments Funding for this work was provided by the Department of Energy and Climate Change (UK). Photo-identification data were collected during a series of grants and contracts from the BES, ASAB, Greenpeace Environmental Trust, Scottish Natural Heritage, Scottish Government, Whale and Dolphin Conservation, Talisman Energy (UK) Ltd., DECC, Chevron, and the Natural Environment Research Council. All survey work was carried out under Scottish Natural Heritage Animal Scientific Licences. The authors have no conflict of interest to declare. We thank Mark Bravington for his helpful advice at the early stages of this work and two anonymous reviewers for their useful comments on the manuscript.

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N2 - Accurate estimates of fecundity rate are key to population assessments and effectively direct conservation efforts. We present a new approach to estimate fecundity rate based on the probability of a female giving birth, conditional on a previous birth t years ago, from which an expected inter-birth interval (IBI) can be estimated. We use generalized linear mixed-effects models to account for individual and temporal variability and apply the approach to individual reproductive histories of bottlenose dolphins (Tursiops truncatus) from the east coast of Scotland. We estimate a fecundity rate of 0.222 (95% CI = 0.218–0.253) and an expected IBI of 4.49 yr (95% CI = 3.94–4.93 yr). We use simulated data samples to show that the approach produces estimates with a minimum bias of <3%. Simulations are also used to investigate the effect of the most common data-driven biases in the estimates of birth intervals and fecundity rate; we recommend longitudinal studies of at least 10 yr and capture probabilities of at least 0.3 when using this methodology. The approach may be modified to incorporate other parameters of interest and should be applicable to any population with comprehensive data on birth intervals.

AB - Accurate estimates of fecundity rate are key to population assessments and effectively direct conservation efforts. We present a new approach to estimate fecundity rate based on the probability of a female giving birth, conditional on a previous birth t years ago, from which an expected inter-birth interval (IBI) can be estimated. We use generalized linear mixed-effects models to account for individual and temporal variability and apply the approach to individual reproductive histories of bottlenose dolphins (Tursiops truncatus) from the east coast of Scotland. We estimate a fecundity rate of 0.222 (95% CI = 0.218–0.253) and an expected IBI of 4.49 yr (95% CI = 3.94–4.93 yr). We use simulated data samples to show that the approach produces estimates with a minimum bias of <3%. Simulations are also used to investigate the effect of the most common data-driven biases in the estimates of birth intervals and fecundity rate; we recommend longitudinal studies of at least 10 yr and capture probabilities of at least 0.3 when using this methodology. The approach may be modified to incorporate other parameters of interest and should be applicable to any population with comprehensive data on birth intervals.

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KW - birth probability

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KW - generalized linear mixed models

KW - mark-recapture data

U2 - 10.1002/ecs2.1796

DO - 10.1002/ecs2.1796

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SN - 2150-8925

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JO - Ecosphere

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M1 - e01796

ER -

A new approach to estimate fecundity rate from inter-birth intervals

Abstract

Bibliographical note

Keywords

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