Preservation of America's Wildlife

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  • WILD HORSE POPULATION GROWTH

    Kathleen Gregg Environmental Researcher

    Lisa LeBlanc Environmental Researcher

    Jesica Johnston Environmental Scientist

    April 25, 2014

    INTRODUCTION

    The recent National Academy of Science (NAS) report on the Wild Horse and Burro Program determined that the Bureau of Land Management (BLM) has no evidence of excess wild horses and burros; because the BLM has failed to use scientifically sound methods to estimate the populations (NAS, 2013). The NAS cited two chief criticisms of the Wild Horse and Burro Program: unsubstantiated population estimates in herd management areas (HMA), and management decisions that are not based in science (NAS, 2013). 

    Effective wild horse and burro management is dependent on accurate population counts and defensible assumptions. The Bureau of Land Management (BLM) routinely uses the assumption that wild horse and burro herds increase annually at an average rate of 20%.  However, our review of available scientific literature combined with an analysis of BLM data for 5,859 wild horses found that approximately 50% of the foals survived to the age of 1 year, which indicates a 10% population growth rate based on yearling survival rates.

    METHODS AND DATA

    The data and analysis is based on the BLM’s wild horse and burro removal and processing documents acquired under the Freedom of Information Act. The data sets were evaluated separately, and then combined to total 5,859 wild horses, captured, aged, and branded by BLM.  This data is the basis for the analysis in this report and the accompanying chart in table 1 below.

    Burro data was also calculated for foal and yearling survival. That data indicated a 7% population growth rate for burros based on yearling survival, but that data is not included here as burros are not present in all of the HMAs.

    The data was collected from 4 herds captured by BLM in Nevada and California in 2010 and 2011. The data below in table 1 shows the individual herds and accumulated age structure data which supports the overall conclusion. Wild horse foals and yearlings were tallied for population increases and in all four samples, recorded a combined foaling rate of less than 20%, but only half or 50% survived to the age of 1 year (see table 1 below).

    Table 1 Age Structure Yearling Survival Rate

    DISCUSSION

    This research does not include or reflect the additional adult mortality rates due to the complexity of population dynamics, but does raise serious questions about the validity of the BLM’s assumed 20% annual herd population growth rate. Furthermore, the BLMs assumption fails to consider that wild horse populations are dynamic due to isolation and have varied rates of reproduction and survival due to changing climates, forage, competition, disturbance and environmental conditions.  All these are factors that can lead to varied herd growth rates and each herd should be evaluated separately.

    This research paper is supported by previous studies using age structure data completed by Michael L. Wolfe, Jr. in 1980 titled “Feral Horse Demography: A Preliminary Report”. Mr. Wolfe cited observations in 12 HMAs, over a period of 2 to 5 years, and covered a much broader range over six Western states. He questioned the annual rate increase of 20%, and found that first-year survival rates to range between 50% and 70% (Wolfe, 1980).

    Other supporting research includes The National Academy of Science National Wild and Free-Roaming Horse and Burro report of 1982, which states, “…several biases in the (BLM) census data, cited or calculated rates of increase based on a number of published values for reproduction and survival rates, as well as sex and age ratios, and concluded annual rates of increase of ten percent or less” (NAS, 1982).

    The NAS 2013 report also used age structure data to estimate population growth. However, the report used foaling rates to draw conclusions about the population growth; rather than first year survival rates (NAS, pg.51-52 2013). This and other studies challenge the assumption that the 20% foaling rate provides an adequate measure of population growth.

    The BLM bases their management decisions on environmental assessments that cite inflated population estimates. As shown in this study and previous research, the BLM’s assumption of a 20% annual wild horse population growth rate is not based in science; leading to unsubstantiated population estimates with no evidence of excess wild horses.

    REFERENCES

    National Academy of Science 2013, “Using Science to Improve the BLM Wild Horse and Burro Program – A Way Forward”

    http://www.nap.edu/openbook.php?record_id=13511&page=R1

    Johnston, J. (2011). California’s, Wild Horses and Burros: Twin Peaks HMA.

    http://csusdspace.calstate.edu/xmlui/bitstream/handle/10211.9/1492/WHB_Thesis_Final%2011.30.11.pdf?sequence=1

    “Feral Horse Demography: A Preliminary Report”, Michael L. Wolfe, Jr.

    http://www.jstor.org/discover/10.2307/3897882?uid=3739560&uid=2&uid=4&uid=3739256&sid=21103688884451

    National Academy of Science 1982, “Wild and Free-Roaming Horses and Burros”

    http://books.google.com/books?id=Q2IrAAAAYAAJ&printsec=frontcover#v=onepage&q&f=false

    U.S. Department of the Interior, Bureau of Land Management Freedom Of Information Act (2012). FOIA BLM FY12-011 1278.

    U.S. Department of the Interior, Bureau of Land Management Freedom Of Information Act (2012). FOIA BLM-2012-00934.

    U.S. Department of the Interior, Bureau of Land Management Freedom Of Information Act (2012). FOIA BLM 2012-01046.

    U.S. Department of the Interior, Bureau of Land Management Freedom Of Information Act (2012). FOIA  BLM 2012-00250.

  • BLM AGAIN Releases Fraudulent Population Statistics for Wild Horses and Burros

    Kathleen Gregg, Environmental Researcher and
    Michele Anderson, Environmental Researcher

    “BLM states biologically impossible annual
    wild horse population rates…”

    Photo by Jesica Johnston

    The Bureau of Land Management (BLM) recently posted their annual Wild Horse and Burro Herd Statistics. As in previous years, BLM’s report is full of obviously false, biologically impossible population growth data.

    WHY is it important to expose this fraud? Because BLM uses the phony figures to convince everyone (but especially, the Congress) that an overpopulation crisis exists.  Given the “crisis,” BLM requests millions of dollars in funding to capture and remove thousands of wild horses and burros from the range or, alternatively, to sterilize them.  The fraudulent figures reflect BLM’s corruption.  Yet, the Agency is granted deference, as if it were providing true data.

    BLM’s falsified population figures affect not only specific herds (by triggering unwarranted, excessive roundups) but also misrepresent the total wild horse and burro population.  The astronomically high numbers for certain herds significantly inflate the summary data, making it seem as if all herds grow at a high rate.

    Here are just a few of the many false figures that BLM is alleging for the reporting-year beginning March 1st, 2022, and ending February 29th, 2023:

    WARM SPRINGS Herd Management Area (HMA) a 497% increase in ONE year (per BLM, a herd of 30 horses produced 149 successful foals in one year which would require that every single horse – including the stallions! – have more than four surviving foals in one year. Biologically impossible

    TOBIN RANGE Herd Management Area (HMA) a 377% increase in ONE year (pe BLM a herd of 30 horses produced 113 successful foals in one year which would require that every single horse – including the stallions! – have more than three surviving foals in one year. Biologically impossible

    HARDTRIGGER Herd Management Area (HMA) a 371% increase in ONE year (per BLM a herd of 14 horses produced 52 successful foals in one year which would require that every single horse – including the stallions! – have more than three surviving foals in one year. Biologically impossible

    SNOWSTORM Mts. Herd Management Area (HMA) a 252% increase in ONE year (per BLM a herd of 90 horses produced 227 successful foals in one year which would require that every single horse – including the stallions! – have more than two surviving foals in one year. Biologically impossible

    DIAMOND HILLS SOUTH Herd Management Area (HMA) a 187% increase in ONE year (per BLM a herd of 216 horses produced 404 successful foals in one year which would require that every single horse – including the stallions! – have more than one surviving foal in one year. Biologically impossible

    DIAMOND HILLS NORTH Herd Management Area (HMA) a 129% increase in ONE year (per BLM a herd of 271 horses produced 349 successful foals in one year which would require that every single horse – including the stallions! – have more than one surviving foal in one year. Biologically impossible

    Not only are these false statements misleading to Congress and to the public but the perpetrators (BLM) of these fraudulent population increases are in violation of Title 18 (18 U.S.C. § 1001).Making false statements (18 U.S.C. § 1001) is the common name for the United States federal CRIME laid out in Section 1001 of Title 18 of the United States Code, which prohibits making false or fraudulent statements, in “any matter within the jurisdiction” of the federal government of the United States, 18 U.S. Code § 1519. Whoever, in any matter within the jurisdiction of the executive, legislative, or judicial branch of the Government of the United States, violates this federal crime shall be fined under this title, imprisoned not more than 5 years.

    Horses and burros have an approximate 11-month gestation period but as shown above and in their statistics, BLM continually gives biologically impossible annual herd increases. A recent study of 5,859 wild horses showed that although the average annual birth rate was about 20%, the survival to the age of yearling was only half of those – therefore a maximum herd increase of only 10%. In addition, adult mortality must be factored which therefore reduces the average herd increase to less than 10% annually.

    The National Academy of Science report cited two chief criticisms of the Wild Horse and Burro Program: unsubstantiated population estimates in herd management areas (HMA), and management decisions that are not based in science (NAS, 2013).  The BLM’s biologically impossible and scientifically indefensible population-growth rates constitute dishonest and distorted data, which the BLM uses to mislead Congress and the American people

    WHY is this so important? Because these are the statistics that BLM gives to Congress when requesting funding for wild horse and burro capture and management plans, including the recent BLM $1-Billion Wild Horse Disaster Plan that pushes for massive roundups and the destruction of wild horse social behaviors through surgical and chemical sterilization for both mares and stallions. . These false population statements are a federal crime punishable by prison and a fraudulent action against the American public in addition to being a travesty against our wild horses and burros.