About

H. Resit Akcakaya is a Professor in the Department of Ecology & Evolution at Stony Brook University. He holds a Ph.D. from Stony Brook University obtained in 1989. His research focuses on developing and applying quantitative methods to address questions in conservation biology and environmental risk assessment. His work includes developing methods to link climate change models, species distribution or habitat suitability models, and metapopulation models with dynamic spatial structures to predict the vulnerability of species to global climate change. He is also interested in methods to quantify and analyze the threat status and trends of biodiversity, including estimating spatial and temporal uncertainties in threatened species assessments based on the IUCN Red List Categories and Criteria. Additionally, his research involves using habitat-based metapopulation models to estimate extinction risks and evaluate conservation strategies, developing new methods for modeling population dynamics, and assessing ecological impacts of pollutants at the population and species levels. His contributions aim to enhance understanding and management of biodiversity conservation challenges through quantitative modeling and analysis.

Research topics

• Computer Science
• Biology
• Computer Security
• Ecology
• Environmental resource management
• Demography
• Geography
• Environmental science
• Business

Selected publications

• Multi-species modelling to improve conservation decision-making for understudied taxonomic groups

  Biological Conservation · 2026-04-22

  articleOpen access

  The rapid and ongoing loss of global biodiversity has led to more species in need of legal protection, and an increasing emphasis on evaluating extinction risk. International and national conservation agencies, such as the International Union on the Conservation of Nature or the Committee on the Status of Wildlife in Canada, are often tasked with assessing extinction risk in species. They rely on very specific and quantitative criteria. However, in understudied taxonomic groups where traditional monitoring efforts are rare and/or unfeasible, many species have historically lacked sufficient data to evaluate these criteria. As a result, they often go unassessed or if they are assessed, they are evaluated as data-deficient. We outline how occupancy models could be harnessed in these understudied groups to help assess species (and potentially avoid a data-deficient assessment) by integrating increasingly important data sources, such as participatory science and remote sensing data. Further, whereas single-species occupancy models (SSOMs) are data-hungry, multi-species occupancy models (MSOMs) (which are also data hungry) pool information across species, allowing data-scarce species to “borrow strength” from data-rich species, thus alleviating some data volume constraints. Using a case study of Canadian butterflies, we compared occupancy trends using an MSOM approach to a SSOM approach. We found that trend estimates converged on a stable value for all species using an MSOM, but SSOM estimates did not converge for many species. We also obtained more precise estimates of trends when using MSOMs compared to SSOMs. These trends obtained from MSOMs would allow the assessment of species that would otherwise be excluded. We discuss strengths, outstanding considerations and current limitations for this modelling approach. Finally, we explore at which stages of the Red List assessment MSOMs will be most beneficial. We argue that using MSOMs as a tool in regional, national, and global species conservation status assessments would allow for more precise estimates of risk in data-scarce species. • Single-species occupancy models are data-hungry and struggle to converge. • This is particularly problematic in data-poor species. • Multi-species models (using the same data) overcome these challenges. • They yielded robust and more precise estimates than single-species models. • This could enable more extinction assessments in understudied taxonomic groups.

  PublisherDOI

• Identifying and ranking species that need urgent management action to achieve Target 4 of the Global Biodiversity Framework

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-04-14

  article1st authorCorresponding

  Abstract Target 4 of the Kunming–Montreal Global Biodiversity Framework (KMGBF) calls for urgent management actions to halt human⍰induced extinctions and enable species recovery. However, most Parties face substantial challenges in determining which species require urgent management actions. Here, we present a transparent, standardised protocol that identifies and ranks species most likely to need urgent management actions at the national level, using globally available data from the IUCN Red List of Threatened Species. The protocol integrates four criteria aligned with Target 4: global extinction risk, rate of decline, population or range restriction, and endemism, to generate a national ranked list of species. Species scoring highly on these four criteria, and therefore most in need of urgent management action, are ranked most highly. We applied this method to all 250 countries and territories listed in the IUCN Red List and pilot⍰tested national rankings with participants from eight diverse countries. Across pilots, participants reported that the ranked lists were scientifically robust, time⍰saving, and valuable starting points for national priority⍰setting, while stating the importance of national context, and the need for additional technical and financial support for implementation. Our results demonstrate that a science⍰based approach can meaningfully support Parties in identifying species requiring urgent action under Target 4, in a standardised way. With 2030 approaching rapidly, this protocol provides an immediate, practical tool to accelerate progress toward halting extinctions and advancing species recovery.

  PublisherDOI

• A global indicator of species recovery

  Conservation Biology · 2025-06-09 · 3 citations

  articleOpen access1st authorCorresponding

  Monitoring progress toward meeting global biodiversity goals involves several indicators, including, at the species level, the International Union for Conservation of Nature (IUCN) Red List Index (RLI) and the Living Planet Index (LPI). However, at present, there is no indicator specifically for tracking species recovery, despite this being enshrined in the mission of the Convention on Biological Diversity's Kunming-Montreal Global Biodiversity Framework (GBF). The IUCN recently adopted the Green Status of Species (GSS), a global standard for measuring species recovery and for assessing the role played by conservation in species recovery. An index based on GSS has been adopted as an indicator for multiple elements of GBF. However, a methodology underpinning the index itself has not previously been published or elaborated. We have therefore developed the Green Status Index of Species Recovery (GSI) for use as a global indicator of progress toward species recovery. We devised GSI to reflect the uncertainties of the underlying GSS assessments and developed methods to disaggregate its global value to reflect the contribution of each country to the recovery of the species within its borders. Overall, we designed the GSI to exhibit key attributes of an effective global indicator, including an explicit objective aligned with global biodiversity goals and a sound methodological basis. The GSI complements existing indicators, such as RLI and LPI, because it fills an important niche in measuring biodiversity trends, going beyond extinction risk and population abundance. As a test, we applied the GSI to a set of species and found that these species were less than halfway to full recovery and moved farther away from full recovery since the mid-20th century. Although the deployment of GSI for complete taxonomic groups will require a considerable scaling up of effort, a sampled approach is feasible and can be operational by 2030.

  PublisherOA PDFDOI

• Ecological Risk–Benefit Analysis for Assisted Colonization

  Global Change Biology · 2025-11-01 · 1 citations

  articleOpen accessSenior authorCorresponding

  Assisted colonization (AC), translocating a species outside its indigenous range to avoid its extinction, is one of the few conservation options for some species. It is also controversial because of the history of ecological impacts of invasive species, including the extinction of native species as a result of novel ecological interactions resulting from the introduction. Although several national and international organizations have issued guidelines related to AC, none allow case-specific decision-making based on risks and benefits to biodiversity. We propose a two-pronged approach to fill this gap. The first step aims to separate clear-cut cases of AC from those that require an in-depth risk analysis. We propose a set of seven qualitative criteria to identify AC projects that are clearly low-risk and high-benefit, and therefore should not be controversial, and those that are clearly high-risk or low-benefit and therefore should not be attempted. This identifies only the most obvious cases, leaving out many cases to be determined through a quantitative analysis to estimate the probabilities of extirpation of the resident species because of AC, which is the second step of our approach. We propose a roadmap for developing such a system based on community ecology theory, and a framework for considering the estimated probabilities in a global context. Our framework recommends an AC project only if it would result in a larger number of globally extant species than a scenario of no action. We propose large-scale testing of the clear-cut approach, further development of the quantitative approach, and wide consultation for adopting international guidelines for risk assessment of AC projects.

  PublisherOA PDFDOI

• Evaluating past and future contributions of conservation programs to species recovery

  Conservation Biology · 2025-11-25 · 1 citations

  articleOpen access

  Impact evaluation of conservation actions is a crucial step in global efforts to curb the biodiversity crisis. Through robust impact evaluation, practitioners can assess the effectiveness of conservation strategies and optimize the use of limited resources. Despite a proliferation of methods and tools for evaluating conservation impact, no standardized method exists to assess and compare the impact, and global contribution, of species recovery programs. To address this gap, we devised an evaluation framework, based on the International Union for Conservation of Nature (IUCN) Green Status of Species (GSS), a global standard for measuring species recovery. We sought to provide a way for conservation program delivery partners to evaluate the effectiveness of their programs in contributing to global species recovery. We adapted 2 scenarios used in GSS assessments to estimate the impact of worldwide conservation actions on a species (the counterfactual current scenario and the future without conservation scenario), in order to propose a new assessment: the program GSS, a method allowing conservation practitioners to estimate the past and potential future impacts of a conservation program relative to the global impact. To identify the strengths and limitations of applying the GSS method at the program level and to gather proof of concept for our adaptation, we tested the proposed method on 16 species recovery programs. The program GSS approach identified past or future impacts of program actions on species status in 9 of the programs assessed. The detectability of program impact and the relative impact of the program compared with global impact were influenced by time since program establishment and program scope (i.e., proportion of a species' population or distribution included in the program). Our framework for program GSS assessments can provide practitioners with a standard, straightforward, and cost-effective way to communicate conservation successes and expected future impacts. Results from our program GSS framework can be compared with the global recovery of a species (conservation legacy and conservation impact) and thus indicate a program's contribution to the recovery of the entire species.

  PublisherOA PDFDOI

• Measuring trends in extinction risk: a review of two decades of development and application of the Red List Index

  Philosophical Transactions of the Royal Society B Biological Sciences · 2025-01-09 · 26 citations

  reviewOpen access

  The Red List Index (RLI) is an indicator of the average extinction risk of groups of species and reflects trends in this through time. It is calculated from the number of species in each category on the IUCN Red List of Threatened Species, with trends influenced by the number moving between categories when reassessed owing to genuine improvement or deterioration in status. The global RLI is aggregated across multiple taxonomic groups and can be disaggregated to show trends for subsets of species (e.g. migratory species), or driven by particular factors (e.g. international trade). National RLIs have been generated through either repeated assessments of national extinction risk in each country or through disaggregating the global index and weighting each species by the proportion of its range in each country. The RLI has achieved wide policy uptake, including by the Convention on Biological Diversity and the United Nations Sustainable Development Goals. Future priorities include expanding its taxonomic coverage, applying the RLI to the goals and targets of the Kunming-Montreal Global Biodiversity Framework, incorporating uncertainty in the underlying Red List assessments, integrating into national RLIs the impact of a country on species' extinction risk abroad, and improving analysis of the factors driving trends.This article is part of the discussion theme issue 'Bending the curve towards nature recovery: building on Georgina Mace's legacy for a biodiverse future'.

  PublisherDOI

• Extinction risk categorization in the IUCN Red List: Comment on “The US Endangered Species Act and acceptable risk”

  Biological Conservation · 2024-10-08

  article1st authorCorresponding
  PublisherDOI

• Accelerating and standardising IUCN Red List assessments with sRedList

  Biological Conservation · 2024-08-23 · 23 citations

  articleOpen access

  The IUCN Red List of Threatened Species underpins much decision-making in conservation and plays a key role in monitoring the status and trends of biodiversity. However, the shortage of funds and assessor capacity slows the uptake of novel data and techniques, hampering its currency, applicability, consistency and long-term viability. To help address this, we developed sRedList, a user-friendly online platform that assists Red List assessors through a step-by-step process to estimate key parameters in a standardised and reproducible fashion. Through the platform, assessors can swiftly generate outputs including species' range maps, lists of countries of occurrence, lower and upper bounds of area of occupancy, habitat preferences, trends in area of habitat, and levels of fragmentation. sRedList is compliant with the IUCN Red List guidelines and outputs are interoperable with the Species Information Service (SIS; the IUCN Red List database) in support of global, regional and national assessments and reassessments. sRedList can also help assessors prioritise species for reassessment. sRedList was released in October 2023, with a complete documentation package (including text documentation, ‘cheatsheets’, and 15 video tutorials), and will soon be highlighted in the official Red List online training course. sRedList will help to bridge the gap between extinction risk research and Red List assessment practice, increase the taxonomic coverage and consistency of assessments, and ensure the IUCN Red List is up-to-date to best support conservation policy and practice across the world. • While central in conservation, the Red List faces major challenges to expand and update. • Methods aiming to support assessors with automated tools remain mostly academic exercises. • sRedList was developed to bridge that gap and make science easily accessible to Red List assessors. • It enables compiling information and calculating key parameters of Red List assessments. • sRedList will help to make the Red List more complete, up-to-date, and standardised.

  PublisherDOI

• Experimental evidence that competition strength scales with ecological similarity: a case study using Anolis lizards

  Oecologia · 2024-01-20 · 4 citations

  articleOpen accessSenior author
  PublisherOA PDFDOI

• The potential for species distribution models to distinguish source populations from sinks

  Journal of Animal Ecology · 2024-10-21 · 2 citations

  articleSenior author

  Abstract While species distribution models (SDM) are frequently used to predict species occurrences to help inform conservation management, there is limited evidence evaluating whether habitat suitability can reliably predict intrinsic growth rates or distinguish source populations from sinks. Filling this knowledge gap is critical for conservation science, as applications of SDMs for management purposes ultimately depend on these typically unobserved population or metapopulation dynamics. Using linear regression, we associated previously published population level estimates of intrinsic growth and abundance derived from a Bayesian analysis of mark‐recapture data for 17 bird species found in the contiguous United States with SDM habitat suitability estimates fitted here to opportunistic data for these same species. We then used the area under the ROC curve (AUC) to measure how well SDMs can distinguish populations categorized as sources and sinks. We built SDMs using two different approaches, boosted regression trees (BRT) and generalized linear models (GLM), and compared their source/sink predictive performance. Each SDM was built with presence points obtained from eBird (a web‐available database) and 10 environmental variables previously selected to model intrinsic growth rates and abundance for these species. We show that SDMs built with opportunistic data are poor predictors of species demography in general; both BRT and GLM explained very little spatial variation of intrinsic growth rate and population abundance (median R 2 across 17 species was close to 0.1 for both SDM methods). SDMs, however, estimated higher suitability for source populations as compared to sinks. Out of 13 species which had both source and sink populations, both BRT and GLM had AUC values greater than 0.7 for 7 species when discriminating between sources and sinks. Habitat suitability have the potential to be a useful measure to indicate a population's ability to sustain itself as a source population; however more research on a diverse set of taxa is essential to fully explore this potential. This interpretation of habitat suitability can be particularly useful for conservation practice, and identification of explicit cases of when and how SDMs fail to match population demography can be informative for advancing ecological theory.

  PublisherDOI

Recent grants

• SBIR Phase II: Assessing Status and Trends of Threatened Species from Uncertain Monitoring Data: Methodology and Software

  NSF · $500k · 2005–2007

Frequent coauthors

• David A. Keith

  60 shared

• Stuart H. M. Butchart

  59 shared

• Thomas M. Brooks

  International Union for Conservation of Nature

  40 shared

• Michael Hoffmann

  Zoological Society of London

  30 shared

• Mark A. Burgman

  25 shared

• Simon N. Stuart

  22 shared

• Lev R. Ginzburg

  22 shared

• Jon Paul Rodrı́guez

  22 shared