Population 

modeling of 

endangered 

species

Valery E. Forbes

School of Biological 

Sciences

EMPM Meeting

October 28, 2014
 NAS Report advocates population 

modeling for T&E species

 Provides little/no specific guidance

 EU has been moving forward in the use 

of population modeling for ERA

 Workshops (Pellston-DK, LEMTOX, 

RUC09, Modelink)

 Research Programs (CREAM)

 Scientific Opinions (EFSA, 

SCHER/SCENIHR/SCCS)

CropLife America 2014 Science Forum–

Why?
*Total US T&E: 1560 & 

going up!

• Plants: 886

• Fish: 164

• Birds: 99

• Mammals: 93

• Clams: 88

• Insects: 72

• Snails: 46

• Reptiles: 37

• Amphibians: 36

*As of 15 Oct 2014

How big is the problem?
 How do we decide which species to 

model?

 How do we decide which models to use?

 What do we do if we’re missing critical 

data?

 How to address uncertainties in model 

outputs?

 How do the models fit into the decisionmaking framework?

We can’t model every single species!
 Overall Aim: Gain better understanding of 

population models and how they can be used in 

T&E species assessments for pesticides in US.

 Main Outputs: Set of recommendations to be 

published in a peer-reviewed journal; SETAC 

Vancouver Session

CropLife America Science Forum
• Valery Forbes, Univ of Nebraska (chair)

• Richard Brain, Syngenta

• Dan Edwards, BASF

• Nika Galic, Univ of Nebraska

• Tilghman Hall, Bayer CropScience

• Joy Honegger, Monsanto

• Carolyn Meyer, ARCADIS

• Dwayne Moore, Intrinsik Environmental Sciences

• Diane Nacci, US EPA

• Rob Pastorok, Integral Consulting

• Thomas Preuss, Bayer CropScience

• Steve Railsback, Humboldt State University

• Chris Salice, Towson Univ

• Richard Sibly, Univ of Reading

• Brigitte Tenhumberg, Univ of Nebraska

• Pernille Thorbek, Syngenta

• Magnus Wang, WSC Scientific

Expert Panel Members
 Individual-Level Models

 Toxicokinetic/toxicodynamic

 Energy budget

 Population-Level Models

 Scalar

 Matrix

 Metapopulation

 Individual-based

The Modeling Toolbox
 Provide quantitative risk estimates 

 Incorporate realistic variability in 

environmental and demographic factors 

 Integrate complex patterns of exposure and 

effects

 Include present factors that have caused the 

species to be listed (e.g., habitat loss, 

invasive species) or resulted in positive 

management action as baseline 

We conclude that models for T&E RA 

should:
We advocate for:

• A multipartite advisory committee to guide model 

implementation and use

• More systematic collection, digitization, and 

dissemination of data for listed species 

• Good Modeling Practice 

• Review of existing population models and their 

applicability

• Case studies to demonstrate proof of concept
Priorities for Research:

• Quantitative analysis of causes of species 

listings to guide model development 

• Systematic assessment of the relative role of 

toxicity versus other factors in driving pesticide 

risk 

• Study how interactions between density

dependence and pesticides influence risk

• Pragmatic approaches for assessing indirect 

effects of pesticides on listed species
• Peer-reviewed publication of the workshop 

outputs –under review in IEAM

• SETAC Vancouver Session: Population modeling

to assess pesticide risks to representative, 

threatened and endangered species: State-of-theart and future directions; Chairs: Forbes, 

Thorbek, Pastorok; Tue a.m.

• Literature review of available models –

in progress; preliminary results to

be presented in Vancouver

Next Steps
Structure of the Literature Review

• Level of organization

• Model type

• Family/Species

• Species status

• Stressors studied

• Processes modeled

• Model outputs

• Risk estimate

• Degree of readiness

• Sensitivity analysis

• Density dependence

• Time horizon

• Spatial scale

• Validation
Contact Info: vforbes3@unl.edu