An Equal Opportunity Provider and Employer

March 1, 2019

Adam Carlesco, Staff Counsel 

Public Employees for Environmental Responsibility 

962 Wayne Ave, Suite 610 

Silver Spring, MD 20910 

Tel: 202.265.7337 

Fax: 202.265.4192 

Email: acarlesco@peer.org

Dear Mr. Carlesco,

We have reviewed your Information Quality Compliant requesting that APHIS 

retract the University of California, Coop. Ext. Serv. Bulletin 1872 publication, 

Connolly, G.E. and W.M. Longhurst, 1975, The Effects of Control on Coyote 

Populations: A simulation Model (“Connolly and Longhurst”). APHIS 

assembled an ad hoc panel to review your Request for Reconsideration and 

assess whether or not our review of your request was conducted with due 

diligence. The review panel was comprised of members of our science

leadership. APHIS Wildlife Services excluded themselves from the panel. The 

panelists independently reviewed the Request for Reconsideration and concluded 

that our response in July 2018 was objective and accurate. 

In your Request for Reconsideration, you cited the age of the Connolly and 

Longhurst’s Bulletin, henceforth referred to in this letter as the ‘C-L Model.’ 

PEER deems this work obsolete due to the age of the publication. The age of 

this study does not necessarily render the work obsolete. The work of the C-L 

Model was based on a study previously done by Frederik F. Knowlton in 1972. 

The C-L Model has foundations in a deer simulation model from the same 

geographical and ecological area (Mendocino County, CA) as the coyote study, 

where concrete coyote data from the county was compared in parallel with the 

simulation, and the local population seemed to actually increase under control 

pressure. This does not support an extermination bias and lack of real-world 

correlations of the model.

Connolly and Longhurst considered the existing literature at the time, stating that 

coyote population numbers cannot be truly controlled by harvesting them. They 

concluded that very high levels of population control are needed to have an 

effect. They determined that 70 percent control is sustainable, and 75 percent is 

at the upper limit of what can be withstood, but even at that extreme, a half 

century must pass at that level to result in any approximation of extermination.

The originators of the C-L Model do consider public perception and the 

acceptability of various control methods, and tout birth control as the best way. 

Preventing animals from being born is presented as preferred control method

over harvesting animals. Connelly and Longhurst repeatedly declare that the 

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rebound rate is dramatic, and there is little concern of endangered designations. The goal 

is to find a balance to decrease depredation versus indescriminate erasure. APHIS 

considers multiple approaches to prevent predation.

A final observation is related to the nature of risk characterization and risk management. 

The intent of risk assessment is for APHIS to determine whether the preponderance of 

evidence support a given program. In addressing coyote management, the Agency has 

used evidence that began with Connolly and Longhurst and has continued to explore 

whether the fundamental findings in that document are backed up by more recent 

modeling research,actual experience, and actual observations. The preponderance of 

evidence, as well as recent modeling tools, show that coyote populations at the landscape 

level are not harmed by local management programs. 

 

APHIS acknowledges the variety of research that shows the limitations inherent in any 

program, and recognizes the value of both lethal and non-lethal approaches. APHIS 

engages in a continuous exploration for new scientific methods and tools and maintains 

cadres of scientists to help inform and advance its mission. We are committed to sharing 

the scientific references that inform our programs. Importantly, the value of population 

management efforts at the local level is substantiated by the continued need expressed by 

landowners and ranchers. Risk management is a compromise between the difficulties 

presented by the management practice and the benefits society enjoys from its 

application. Risk analysis is thus a balance between the nature of risks and the 

effectiveness of risk management measures. The risk associated with coyotes in 

managed lands is documented and current evidence supports that the management of 

local coyote populations advances the needs of landowners and ranchers.. 

The APHIS review panel concluded that the Connelly and Longhurst’s Bulletin has 

generous and appropriate assumptions and conclusions, and responsibly reports the data. 

APHIS believes that the Bulletin remains relevant and timely as a part of a 

comprehensive reference cache for development of predator control programs and overall 

ecosystem management systems in the United States.

Sincerely,

Mary Connie Williams

Information Quality Officer

USDA APHIS