Research & Data

Knowledge Gaps

Documented gaps in the public record — data that does not exist, questions that have not been studied, and transparency that has not been required.

A research depository is defined as much by what it cannot find as by what it contains. The sources in this library are the best available evidence on wild horse management. But the evidence base has structural gaps — things that have not been studied, data that has not been collected, analyses that have not been done — that shape and distort the public debate in ways that rarely get named.

Most of these gaps are not accidents. They reflect the absence of any institution with both the resources and the incentive to fill them. Federal agencies are constrained by mandate and budget. Advocacy organizations on both sides have no interest in generating data that might complicate their position. Academic researchers depend on access and funding that is politically sensitive. The result is a debate conducted with great conviction on the basis of a remarkably incomplete picture.

This page names the gaps as precisely as we can. Where partial data exists, we say so. Where the gap reflects a genuine absence of research, we say that too. If you have knowledge that belongs here — field experience, unpublished data, firsthand observation — we want to hear from you.

Category 01 Population & Identity
01
Critical Gap
No National Population Count
Federal land only — tribal, state, and private land excluded
The BLM's figure of 73,130 horses covers only federal HMA land. Horses on tribal land, state land, and private land — including feral populations that have expanded well beyond HMA boundaries — are not counted in any unified national dataset. Some tribal nations have conducted their own estimates, but coverage is inconsistent and not aggregated. The true national feral horse population is unknown, and the public debate proceeds as though the BLM figure is complete.
Why it hasn't been doneNo federal agency has jurisdiction over non-federal land horse populations. Tribal governments manage their own lands independently. State agencies have no mandate or funding to conduct counts. Nobody owns the problem in full.
What it would takeA multiagency intergovernmental study — BLM, USFS, tribal governments, and state wildlife agencies — with agreed survey methodology and shared reporting standards. Politically complex; no precedent.
02
Significant Gap
No Count of Branded Horses in Feral Populations
The line between feral and escaped domestic is unmeasured
A meaningful but unknown proportion of horses living in feral conditions on non-HMA land — particularly on private and tribal land — are branded, meaning they are legally owned domestic animals that have escaped or been released. No systematic survey has quantified what share of any feral population outside BLM HMAs consists of branded animals versus horses born in the wild. This matters for legal status, liability, management authority, and welfare responsibility — all of which differ depending on whether an animal is legally owned.
Why it hasn't been doneAerial surveys don't reliably capture brand markings. Ground surveys at scale are expensive. No agency has claimed authority over the question, so no agency has funded an answer.
What it would takeTargeted ground surveys in known feral population areas outside HMAs, with brand inspection involvement. A modest study; the gap reflects a lack of interest more than a lack of feasibility.
03
Significant Gap
No Comprehensive Genetic Origin Mapping
Existing testing is partial, focused on diversity — not origins
BLM has conducted genetic sampling in approximately 75% of its HMAs since the early 1990s, focused primarily on diversity metrics and inbreeding risk within managed herds. This is not a national origin map. Testing covers only BLM-managed populations — excluding tribal, state, and private land herds entirely. The 25% of BLM's own HMAs that remain untested represent a further gap. Existing data suggests most herds descended from escaped or released domestic horses rather than pre-Columbian populations, but the picture is herd-by-herd and incomplete. No standardized national origin analysis exists that would allow comparison across jurisdictions or inform reintroduction or management decisions at a population level.
Why it hasn't been doneBLM's genetic program is focused on managing within-herd diversity, not on origin science. Funding is limited. Non-federal populations are not within BLM's mandate to study.
What it would takeExpanded USGS research mandate and funding, with non-invasive sampling methods (hair and dung DNA) that don't require gather operations to collect samples across non-federal populations.
04
Significant Gap
No Standardized Survey Methodology Across Jurisdictions
BLM, USFS, tribal, and state agencies count differently
The BLM has used peer-reviewed aerial survey methods across its HMAs since 2013, but the NAS 2013 report found these direct count methods underestimate populations by 20–30% by failing to account for undetected animals. USFS, tribal governments, and state agencies use different or no standardized methods. There is no common reporting framework, no shared correction factor, and no interagency database. Any aggregate national figure drawn from these sources combines incompatible methodologies — making trend analysis across jurisdictions unreliable.
Why it hasn't been doneInteragency coordination on methodology requires sustained political will and shared funding. Each agency's survey practices reflect its own mandate and budget constraints. There is no lead agency for cross-jurisdictional horse data.
What it would takeA federal interagency working group — likely convened through Interior — with a mandate to develop shared survey standards and a common reporting database. The NAS 2013 report recommended this; it has not been implemented.
Category 02 Economics & Fiscal Impact
05
Critical Gap
No Monetized Damage Estimate
Rangeland degradation has no dollar figure attached to it
The ecological damage caused by horse overpopulation — degraded watersheds, loss of native plant communities, displacement of wildlife, erosion, damage to riparian areas — has never been translated into a comprehensive economic estimate. Ranchers and land managers describe real and significant losses, but there is no peer-reviewed quantification of total damage costs attributable to wild horses at either the herd or national level. In the absence of this figure, advocates can dismiss ecological harm as speculative, and policymakers have no basis for cost-benefit comparisons between management options. The fiscal case for management is made almost entirely on BLM program costs, not on the costs the unmanaged population imposes on the land and on other users.
Why it hasn't been doneValuing rangeland ecosystem services is methodologically complex. Federal agencies have no incentive to publish a figure that would escalate political pressure. Academic researchers need access to BLM lands and funding that is politically sensitive.
What it would takeAn independent study — modeled on ecosystem services valuation methodologies used in other rangeland contexts — covering a representative sample of overpopulated HMAs and adjacent private land. Could be conducted by a land-grant university with existing rangeland economics capacity.
06
Critical Gap
No Cost-Benefit Analysis of Domestic Processing
The comparison that's never been done
The policy debate compares "roundup and hold" against "leave on range" — two options that are both fiscally and ecologically unsustainable at scale. The option that is almost never analyzed is domestic processing: what it would cost, what it would save in holding and program costs, what the economic activity would generate in rural communities, and how it compares on animal welfare grounds to the current export pipeline to Mexico and Canada. No peer-reviewed analysis of domestic processing as an economic and welfare alternative to the status quo exists. The debate proceeds without the one comparison that might most change it.
Why it hasn't been donePolitically untouchable for federal agencies. Academic researchers risk grant funding and access by engaging with it. Advocacy organizations on both sides have strong incentives to keep the comparison off the table.
What it would takeAn independent economic analysis — ideally from a land-grant university or policy institute without a stake in the outcome — comparing per-horse costs and welfare outcomes across the full range of options: holding, adoption, fertility control, export, and domestic processing.
07
Significant Gap
No Full Lifecycle Cost Accounting Per Horse
BLM tracks holding costs — not the full picture
BLM reports per-animal holding costs ($2.35/day in long-term pasture, $6/day in short-term corrals) and lifetime care estimates ($15,000 in 2025). These figures exclude gather costs, transport, veterinary preparation, fertility control treatment, adoption marketing, and program administration allocated per animal. A true per-horse lifecycle cost — from gather to final disposition — has not been published. Without it, the cost of adoption versus holding versus processing cannot be accurately compared, and program efficiency claims cannot be independently verified.
Why it hasn't been doneBLM accounting separates program cost categories in ways that make per-animal lifecycle calculation difficult. GAO has flagged cost accounting gaps in prior audits. No corrective action has been taken.
What it would takeA GAO audit specifically focused on per-animal lifecycle costs with a mandate to account for all cost categories. The existing GAO-09-77 audit identified this gap; an updated audit with this specific scope would be valuable.
08
Significant Gap
No Quantification of Grazing Permittee Losses
Rancher harm is described but not measured
Ranchers and grazing permittees on BLM and USFS allotments consistently describe significant economic losses from horse overpopulation — reduced forage availability, damage to water infrastructure, fence damage, and reductions in permitted animal unit months. These losses are real and documented anecdotally but have not been quantified in a peer-reviewed study at any scale. The absence of a dollar figure allows the losses to be dismissed as industry complaint rather than measured harm, and prevents their inclusion in any cost-benefit framework for management decisions.
Why it hasn't been doneRanchers are reluctant to share financial data publicly. Academic access to private ranch records requires trust that takes time to build. Federal agencies don't collect permittee economic impact data systematically.
What it would takeA cooperative study through an agricultural extension program — Wyoming, Nevada, or Utah land-grant universities are natural candidates — with confidential data collection and aggregated reporting to protect individual producers.
Category 03 Animal Welfare
09
Critical Gap
No Transparency in the Slaughter Pipeline
What happens after sale is largely undocumented
USDA tracks horse export shipments to Canada and Mexico by number. What it does not track is how many of those animals were BLM-sourced, what welfare conditions they experienced in transit and at slaughter facilities, or what proportion of BLM Sale Authority horses enter the export pipeline within days of title transfer. The Adoption Incentive Program was shut down in 2025 after documentation showed horses entering kill pens immediately after title transfer — but the Sale Authority program that replaced it has no post-transfer tracking. The slaughter pipeline is functionally invisible once an animal leaves federal custody.
Why it hasn't been doneBLM's legal obligation ends at title transfer. USDA's export tracking is by volume, not by origin. Slaughter facilities in Mexico and Canada operate outside US inspection jurisdiction. No agency has claimed responsibility for post-transfer outcomes.
What it would takeA USDA-BLM data-sharing agreement to track BLM-issued freeze brands through export manifests. Combined with independent welfare audits at receiving facilities — which would require diplomatic cooperation with Canada and Mexico.
10
Critical Gap
No Comparative Welfare Analysis Across Disposition Options
The welfare argument is made loudly by all sides with almost no data
Anti-processing advocates argue that any processing is inhumane. Pro-management advocates argue that starvation on an overpopulated range, long-distance export to Mexican slaughter facilities, and indefinite confinement in holding corrals are all more harmful than domestic processing. Both positions are argued with conviction. Neither is supported by a rigorous comparative welfare analysis across all options: overpopulated range, long-term holding, export to Canada, export to Mexico, and domestic processing under USDA inspection. The welfare debate is almost entirely definitional — about what counts as humane — rather than empirical.
Why it hasn't been donePolitically untouchable. Any researcher publishing a welfare comparison that shows domestic processing favorably against export alternatives risks funding, access, and professional reputation. The AVMA has position statements but no comparative analysis.
What it would takeAn independent veterinary science study — ideally multi-institutional — using established animal welfare assessment frameworks (Five Domains, Five Freedoms) applied consistently across all disposition scenarios. Would require cooperation from facilities across multiple countries.
11
Significant Gap
No Independent Audit of Long-Term Holding Facilities
BLM self-reports welfare outcomes — no third-party framework
Approximately 64,000 horses are currently held in BLM long-term holding facilities, more than live free on any range. BLM reports on these facilities internally. No independent third-party audit framework exists for evaluating welfare conditions at scale across the corral and pasture system. The advocacy community photographs and visits individual facilities but produces advocacy materials, not systematic welfare assessments. There is no agreed methodology, no baseline standard, and no independent body charged with applying one.
Why it hasn't been doneBLM has resisted independent oversight of holding facilities. Advocacy organizations lack the scientific credibility and systematic methodology to conduct audits that would be accepted by all parties. No neutral body has been tasked with this.
What it would takeCongressional direction — likely through appropriations language — requiring BLM to establish an independent welfare audit program for long-term holding facilities, similar to USDA's existing livestock inspection framework.
12
Significant Gap
No Post-Adoption Welfare Tracking
Title transfers — animals disappear from any dataset
Once a wild horse or burro is adopted or sold and title is transferred, federal tracking ends. There is no follow-up welfare assessment, no mandatory reporting of animal disposition, and no way to distinguish horses in good private homes from horses in kill pens. BLM's adoption success metrics count placements — not outcomes. The Adoption Incentive Program collapse demonstrated that placement without outcome tracking is not a welfare policy. The Sale Authority program that replaced it has the same blind spot.
Why it hasn't been donePost-transfer tracking would require a registration system, ongoing data collection, and enforcement capacity that BLM does not currently have. It would also reveal uncomfortable data about placement outcomes that the program has political incentives to avoid documenting.
What it would takeA freeze-brand-based registration and follow-up system, similar to livestock brand registries, with required reporting at 6 and 18 months post-transfer. Would require legislative authority and program funding beyond BLM's current mandate.
Category 04 Ecology & Range Science
13
Significant Gap
No Longitudinal Rangeland Recovery Data
We know overpopulation causes damage — not how long recovery takes
The scientific literature documents the damage wild horse overpopulation causes to rangeland — vegetation loss, soil compaction, riparian degradation, water point damage. What the literature does not contain is a systematic longitudinal study of how long rangeland recovery takes after herd reduction or removal, under what conditions recovery occurs, and whether some damage is effectively permanent at the site level. Without this data, the long-term cost of inaction cannot be accurately estimated, and the ecological case for management is weaker than it should be.
Why it hasn't been doneLongitudinal studies require sustained funding and access over many years. BLM's research budget is concentrated on fertility control and population estimation. Recovery monitoring after gathers is not systematically conducted or published.
What it would takeA paired study design — monitoring vegetation, soil, and wildlife indicators in matched sites before and after herd reduction — sustained over 5–10 years. USGS and university range science departments have the capacity; the gap is funding and mandate.
14
Emerging Gap
No Systematic Wildlife Competition Studies
Sage-grouse, pronghorn, and native ungulates — interaction data is thin
Wild horses share rangeland with sage-grouse, pronghorn, mule deer, and native ungulates — all of which are affected by the same vegetation and water resources. BLM has conducted some studies on horse-sage-grouse habitat overlap, but systematic species-level competition studies across multiple HMAs and species groups do not exist. The ecological argument for management is strongest when it can point to specific wildlife impacts, but the evidence for those impacts is currently thinner than the range degradation evidence, and therefore easier to challenge.
Why it hasn't been doneMulti-species interaction studies require simultaneous monitoring of multiple species across large landscapes — logistically complex and expensive. Wildlife research funding is siloed by species, not by interaction.
What it would takeCollaborative research between BLM, USFWS (for sage-grouse), state wildlife agencies, and university wildlife science programs, coordinated across a representative selection of HMAs with varying population densities.
Help Fill the Gaps

Know Something We Don't?

If you have field experience, unpublished data, agency knowledge, or firsthand observation that bears on any of these gaps — or if you know of research we've missed that partially addresses one — we want to hear from you. Anonymous contact is welcome.

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