A model of seasonal variation in somatic growth rates applied to two temperate turtle species

Matthew G. Keevil, Doug P. Armstrong, Ronald J. Brooks and Jacqueline D. Litzgus

Ecological Modelling, 2021, vol. 443, issue C

Abstract: Modeling somatic growth of animals whose growth rates are seasonally variable is a challenge. Seasonal variation in growth reduces model fit and precision if not accounted for, and ad hoc adjustments to growth models may be biased or biologically unrealistic. We developed a growth phenology model (GPM) that uses a logistic function to model the cumulative proportion of total annual growth. We applied this model using two different approaches to datasets from temperate-climate populations of two freshwater turtle species that experience extended winter dormancy during which no growth occurs. The first dataset consisted of repeated intra-annual observations of sub-adult snapping turtles (Chelydra serpentina) tracked by radio telemetry, which we analyzed in a Bayesian context, focusing on growth over a single season. We then demonstrated a post hoc combination of the fitted GPM with a separate overall growth model. For the second application, we fully integrated the GPM into a hierarchical von Bertalanffy growth model, which we applied to a dataset of primarily inter-annual observations of juvenile midland painted turtles (Chrysemys picta marginata). Specifying informative priors allowed us to fit the model despite the sparseness of intra-annual information in the data. We also demonstrate using the beta cumulative distribution function as an alternative to the logistic function in the GPM. We discuss incorporating prior knowledge about seasonal foraging and activity periods into growth models via a GPM as a transparent alternative to deterministic, implicit, a priori constructs.

Keywords: Von Bertalanffy; Phenology; Bayesian; Bayes; Snapping turtle; Painted turtle; Chelydra; Chrysemys (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations:

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0304380021000272
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:ecomod:v:443:y:2021:i:c:s0304380021000272

DOI: 10.1016/j.ecolmodel.2021.109454

Access Statistics for this article

Ecological Modelling is currently edited by Brian D. Fath

More articles in Ecological Modelling from Elsevier
Bibliographic data for series maintained by Catherine Liu ().