[MARMAM] New publication: Population consequences of disturbance on income-breeding mammals

Elizabeth McHuron emchuron at ucsc.edu
Wed Aug 1 11:48:59 PDT 2018

Dear colleagues,

My co-authors and I are pleased to announce the publication of our new
paper describing the use of a state-dependent model for quantifying the
population consequences of disturbance on income-breeding mammals.

EA McHuron, LK Schwarz, DP Costa, and M Mangel. 2018.   "A state-dependent
model for assessing the population consequences of disturbance on
income-breeding mammals. Ecological Modelling 385: 133-144

*Abstract:* Human activities continue to expand in marine and terrestrial
environments, leading to increased interactions with wildlife that can have
negative impacts on population dynamics. Approaches for quantifying how
these interactions translate to population-level effects are therefore
crucial for effective management practices and balancing human-wildlife
tradeoffs. We developed a method using state-dependent behavioral theory
implemented via Stochastic Dynamic Programming (SDP) for predicting the
population consequences of disturbance on the physiology and reproductive
behavior of an income-breeding mammal, using California sea lions (*Zalophus
californianus*) as a motivating species. Emergent properties of the model
included reproductive characteristics associated with long-lived species,
such as variation in the age at first reproduction, early termination of
pregnancy, and skipped breeding. In undisturbed model simulations,
reproductive rates and the average wean date were consistent with
empirically-derived estimates from sea lions and other marine mammals,
highlighting the utility of this model for quantifying fecundity estimates
of data-deficient species and addressing fundamental ecological processes.
In disturbed model simulations, exposure to prolonged, repetitive
disturbances negatively impacted population growth; in addition, short,
infrequent disturbances had the potential for adverse effects depending on
the behavioral response of sea lions and the probability of being
disturbed. The adverse effect of disturbance on population dynamics was due
to a combination of reduced pup recruitment (survival to age one) resulting
from a lower wean mass and increased abortion rates that led to skipped
reproductive years, both of which have been documented for marine mammal
populations experiencing natural fluctuations in prey availability. The
derivation of state- and time-dependent reproductive decisions using an SDP
model is an effective approach that links behavioral and energetic effects
at the individual level to changes at the population level, and one that
serves a dual purpose in the ability to quantify basic biological
parameters and address ecological questions irrespective of disturbance.
A link to the paper with free access can be found here

Please don't hesitate to contact me if you would like a pdf of the article
and do not have access to the journal (emchuron at ucsc.edu).


Liz McHuron
Elizabeth McHuron, Ph.D.
Research Scientist
University of Washington JISAO
115 McAllister Way
Santa Cruz, CA 95060
emchuron at uw.edu <emchuron at ucsc.edu>
emchuron at ucsc.edu
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