Figure
1.
Current habitat distribution and suitability of the Asian Houbara.
| Citation: |
Gulzaman William, Zafeer Saqib, Abdul Qadir, Nisha Naeem, Mehrban Ali Brohi, Asim Kamran, Afia Rafique. 2025: Assessing the vulnerability of wintering habitats for the red-listed Asian Houbara (Chlamydotis macqueenii) using climate models and human impact assessments. Avian Research, 16(1): 100221. DOI: 10.1016/j.avrs.2024.100221
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The Asian Houbara (Chlamydotis macqueenii), a vulnerable species, is under significant threat from habitat degradation and anthropogenic pressures in Pakistan’s arid landscapes. This study addresses the urgent need for conservation by identifying critical habitats, analyzing the influence of environmental and human factors on species distribution, and projecting future habitat shifts under climate change scenarios. Using the MaxEnt model, which achieves a robust predictive accuracy (AUC = 0.854), we mapped current and future habitat suitability under Shared Socioeconomic Pathways (SSP126, SSP370, SSP585) for the years 2040 and 2070. Presently, the suitable habitat extends over 217,082 km2, with 52,751 km2 classified as highly suitable. Key environmental drivers, identified via the Jackknife test, revealed that annual mean temperature (Bio1) and slope play a dominant role in determining habitat suitability. Projections show significant habitat degradation; however, under SSP585, highly suitable areas are expected to expand by up to 24.92% by 2070. Despite this increase, vast areas remain unsuitable, posing serious risks to population sustainability. Moreover, only 2115 km2 of highly suitable habitat currently falls within protected zones, highlighting a critical conservation shortfall. These findings highlight the imperative for immediate, targeted conservation efforts to secure the species' future in Pakistan’s desert ecosystems.
Chlamydotis macqueenii, commonly known as the Asian Houbara, stands at the brink of decline, and classified as vulnerable on the IUCN Red List (BirdLife International, 2021). Its precarious status is underscored by its inclusion in Appendix Ⅰ of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which imposes stringent restrictions on international trade to prevent further population losses, and in Appendix Ⅱ of the Convention on the Conservation of Migratory Species (CMS), signaling its heightened vulnerability to threats such as hunting and poaching. Though CITES Appendix Ⅰ prohibits commercial trade, exceptions for non-commercial purposes, like scientific research, may be granted under controlled circumstances (BirdLife International, 2021). The global population of the Asian Houbara is difficult to estimate precisely due to its migratory behavior and widespread distribution. However, it is generally projected to range between 50,000 and 99,999 individuals, with variations depending on migration patterns and habitat conditions. Of these, an estimated 33,000 to 67,000 are believed to be mature, reproductive individuals (BirdLife International, 2021).
Ecologically, the Asian Houbara plays a vital role in maintaining the balance of desert environments by contributing to pest control and seed dispersal, which supports the health and diversity of desert flora. As an omnivorous species, it feeds on a variety of plant materials and insects, making it a key player in its ecosystem (Dolman et al., 2021). Additionally, the species serves as a bioindicator, reflecting the overall health of its environment. While dense vegetation provides refuge from potential threats and offers thermal insulation during cold winter nights (Haghani et al., 2018), less vegetated and more open areas are often preferred as roosting sites at night to minimize the risk of ambush by nocturnal predators (Aghanajafizadeh et al., 2012). On the breeding grounds, nesting females tend to select sites away from vegetative patches that could conceal predators. Moreover, the abundance of breeding males is typically greater in flat areas with shorter shrub cover, which appears to be more conducive to display behaviors (Koshkin et al., 2016).
Agricultural expansion, urbanization, and infrastructure development have significantly contributed to the destruction of Asian Houbara habitats, particularly in arid and semi-arid regions. The conversion of desert and scrubland into agricultural fields reduces the availability of suitable nesting and foraging sites, while urban sprawl and infrastructure projects, such as road networks and industrial development, fragment remaining habitats and disrupt movement corridors. For instance, in Pakistan, rapid urbanization and agricultural land conversion have led to the loss of approximately 30% of natural habitats over the past two decades, with arid regions being among the most affected (Bhatti et al., 2020). Additionally, infrastructure development, including road construction in previously undisturbed areas, has exacerbated habitat fragmentation, further isolating populations of Asian Houbara (Usman et al., 2022). These anthropogenic pressures have not only reduced habitat availability but have also increased human disturbance, which negatively impacts breeding success and population stability. However, the principal threat to the species is hunting, predominantly through falconry, which mainly affects their wintering grounds (Azar et al., 2022). This relentless exploitation during critical migration and wintering periods in Pakistan’s deserts has led to severe population declines, underscoring the urgent need for targeted conservation efforts to address both habitat loss and illegal hunting. Additionally, substantial numbers of Asian Houbaras are captured, particularly in Pakistan, and transported to Arabia for falconry training. Hunting and trapping contribute to over 50% of Asian Houbara mortality in Iran (Pakniat et al., 2021). In 2014, authorities intercepted an illicit shipment of 240 birds en route from Pakistan to Bahrain (Ata et al., 2019). In Arab nations, the meat of the Asian Houbara is highly valued for its supposed aphrodisiac properties, attracting high-status hunters (Nabi et al., 2019). From 2017 to 2019, Pakistan issued hunting permits for the Asian Houbara to Arab royalty, and unregulated hunting continues to persist. Moreover, egg collection during the breeding season further exacerbates the species' decline (Pakniat et al., 2021).
The Asian Houbara migrates from the Gobi Desert and Jungar Basin in China, traversing Kazakhstan to reach its wintering grounds in Pakistan deserts ecosystems. The Asian Houbara, a desert adapted bird found in the arid landscapes of Punjab and Sindh, Pakistan, plays a crucial role in the ecological balance of these regions. In this study, the MaxEnt modeling technique was employed to conduct a comprehensive analysis of both current and future habitat conditions. The primary objectives are to identify key areas for immediate conservation efforts, assess the impact of anthropogenic and environmental factors on the Asian Houbara’s distribution, and forecast potential distribution patterns using model-based projections. Understanding these dynamics is essential for developing effective conservation strategies, as future projections will reveal how potential climate and environmental changes could further impact the species. By mapping these aspects, this research aims to provide critical insights that will support targeted interventions and enhance the long-term protection of the Asian Houbara in its desert habitats.
The study was conducted across the three provinces of Punjab, Sindh, and Balochistan in Pakistan. These provinces represent a wide range of diverse ecosystems, including deserts, plains, and mountainous regions. These expansive desert ecosystems, characterized by sandy dunes and sparse vegetation, offer essential habitat conditions during the species' winter migration. The unique convergence of subtropical desert and semi-arid plains in these regions forms an ecological setting crucial for the Asian Houbara, providing indispensable resting and foraging grounds during the winter months. The occurrence records of Asian Houbara were collected in two ways (1) field surveys across the arid regions of Punjab, Sindh, and Balochistan, and (2) data obtained from the Global Biodiversity Information Facility (GBIF) database. The occurrence records of Asian Houbara were gathered through field surveys conducted from 2021 to 2023, which covered a total area of approximately 693,447 km2, including key habitats identified as critical for the species' presence based on previous studies and environmental factors. Survey routes were strategically selected to ensure comprehensive coverage of habitat types relevant to the species, including desert scrublands, and open agricultural fields, commonly used by the Asian Houbara. The survey effort involved 40 to 60 survey days per year, with a team of trained field researchers conducting surveys during the species' peak activity periods. Surveys were conducted on foot, by vehicle, and through aerial methods to maximize coverage and reduce bias. A systematic sampling approach was adopted, with survey points established at regular intervals of 1–5 km to cover both known and potential habitats. A total of 96 GPS locations of wild Asian Houbara were recorded during the field surveys, while an additional 26 occurrence records were downloaded from the GBIF database. After reviewing the GBIF data, any duplicate or inaccurate points were omitted. In ArcGIS 10.8, duplicate records from the combined dataset were removed, followed by spatial filtering using buffer analysis. The resolution of the environmental predictor data employed in this study was 1 km2, and accordingly, a 1 km2 buffer zone was created around each occurrence point. Overlapping buffer zones were removed during the spatial thinning process, ensuring a minimum ground distance of approximately 2 km2 between closely lying points. This filtering process resulted in a final selection of 61 presence points, which were then used in the predictive modeling of the Asian Houbara distribution (Fig. 1).
The 19 bioclimatic variables were derived from long term records of monthly rainfall and temperature data (1950–2000) (Fick and Hijmans, 2017). The data, with a spatial resolution of approximately 1 km2 (30 s), was obtained from the WorldClim dataset (http://www.worldclim.org). Past climatic data were obtained from the paleoclimate models provided by WorldClim, specifically for the Last Glacial Maximum (approximately 21,000 years ago) and the Holocene (around 10,000 years ago). These datasets are derived from global climate models such as the Community Climate System Model (CCSM) and the Max Planck Institute Earth System Model (MPI-ESM) (Cooper et al., 2016; Zhu et al., 2016). To project the future distribution of Asian Houbara, we employed CMIP6 scenarios based on the NOAA GFDL ESM4 (Geophysical Fluid Dynamics Laboratory Earth System Model version 4). Specifically, we used SSP126, SSP370, and SSP585, representing a range of potential future greenhouse gas emission pathways. The NOAA GFDL ESM4, a state-of-the-art climate model, integrates the latest advancements in climate science and has demonstrated resilient performance in simulating observed climate patterns and variability.
The nighttime light data, derived from VIIRS, and the human modification index, sourced from the Global Human Modification (GHM) layer, were downloaded and processed from NASA’s Earth Observing System and the Dryad repository (Elvidge et al., 2017). These variables were overlaid on the current distribution model to assess the extent to which human activities impact the habitat suitability of the Asian Houbara. In total, 19 bioclimatic variables (Bio1–Bio19) and three remote sensing based geomorphometric variables (slope, aspect, and elevation) were analyzed to identify the primary drivers influencing the species' distribution (Dunne et al., 2020) (Appendix Table S1). Elevation is included as a geographical variable in this study due to its indirect influence on species distribution, primarily through its effects on environmental factors such as temperature, precipitation, and vegetation types, which collectively shape habitat suitability. ArcGIS software version 10.8 was employed to generate slope and aspect maps using the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) with a spatial resolution of 30 m, sourced from the Geospatial Data Cloud (http://www.gscloud.cn/). To address multicollinearity among bioclimatic variables (Bio–Bio19), and topographic factors (elevation, slope, aspect), the variables with more than 75% Pearson correlation with each other were excluded (Appendix Table S2). If a mutually dependent predictor was more interpretable, it was retained while the other was excluded (Bradie and Leung, 2017). After this initial screening, the MaxEnt model was run using the uncorrelated variables with default settings. Variables with a model contribution of 4% or less were removed, and the model was optimized to produce the final models and distribution maps. The significance of environmental variables was assessed using contribution percentage and permutation importance. Permutation importance was prioritized for evaluating variable significance due to its effectiveness in providing a clear measure of each variable’s impact on the model results (Songer et al., 2012).
To model the suitable habitat for Asian Houbara in Punjab, Sindh, and Balochistan provinces of Pakistan, the MaxEnt software package (version 3.4.4) was employed. MaxEnt is a widely used machine learning tool that employs the maximum entropy method to model spatial distributions based on presence-only data, delivering promising outcomes. This robust technique excels in handling variations in sample size and effectively generates species response curves based on environmental variables (Khanum et al., 2013). For a precise evaluation of the model’s predictive accuracy, it is critical to use independent data from sites distinct from those used for training. Thus, the species occurrence data were divided into a training set (75% of the total records) and a test set (25%). Environmental variables were meticulously standardized to a 30-m pixel size and formatted as meter ASCII raster grids. The modeling approach incorporated both linear and quadratic features to capture complex environmental interactions. The model’s performance was rigorously assessed using the Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC) plot (Phillips et al., 2006). AUC values, ranging from 0 to 1, offer a precise measure of the model’s discriminative power, with a value of 1 denoting perfect performance (Fielding and Bell, 1997). AUC scores are categorized as follows: scores below 0.5 reflect a model performing worse than random chance, 0.5 indicates random guessing, and scores from 0.5 to 0.6 are considered poor, 0.6 to 0.7 as subpar, 0.7 to 0.8 as reasonable, 0.8 to 0.9 as good, and 0.9 to 1 as exceptional. To pinpoint the key environmental factors driving species distribution, the jackknife test was employed (Yang and He, 2013). Species response curves were developed to reveal how habitat suitability correlates with environmental variables. The resulting species distribution map, with suitability values ranging from 0 to 1, was classified into four distinct categories of habitat suitability: highly suitable habitat (>0.6), moderately suitable habitat (0.4–0.6), poorly suitable habitat (0.2–0.4), and unsuitable habitat (<0.2) (Yang and He, 2013).
The study utilized remote sensing based geomorphometric variables, including slope, aspect, and elevation, along with species occurrence data, to predict the current and future distribution of suitable habitats. Future scenarios were projected for the years 2040 and 2070 under SSP126, SSP370, and SSP585, incorporating anticipated changes in climate. The resulting habitat suitability maps were classified into binary categories (suitable/unsuitable) to facilitate a detailed comparison between current and future conditions. This analysis revealed areas of habitat gain, where previously unsuitable areas are projected to become viable; areas of habitat loss, where currently suitable regions may no longer support the species; and zones of habitat stability, where conditions are expected to remain unchanged (Gallagher et al., 2013). The spatial overlay of these maps within a GIS environment enabled precise quantification of these transformations, providing critical insights into the future landscape for the Asian Houbara. The model’s accuracy was validated through metrics such as the AUC and True Skill Statistic (TSS), ensuring robust and reliable predictions.
The MaxEnt model demonstrating strong predictive accuracy with an AUC value of 0.854, effectively identifying potential habitats for the Asian Houbara across the Cholistan Desert in Punjab, the Thar Desert in Sindh, and parts of Balochistan (Appendix Fig. S1). The model’s performance metrics support its reliability, with a TSS value of 0.64, reflecting a solid balance between sensitivity and specificity, and a correlation coefficient (COR) of 0.36, indicating a moderate correlation between observed and predicted distributions. A deviance value of 0.63 further affirms the model’s reasonable fit. The total area of suitable habitat is estimated at 217,082 km2, comprising 52,751 km2 of highly suitable habitat and 67,357 km2 of moderately suitable habitat, which together represent areas capable of supporting the species. In contrast, 96,974 km2 falls under the category of poorly suitable habitat, which does not meet the threshold for suitability and is therefore classified as unsuitable habitat in this study. The highly suitable, moderately suitable, and poorly suitable habitats constitute 24.3%, 31.0%, and 44.7% of the total area, respectively (Fig. 1).
Key environmental factors influencing habitat suitability were determined through comprehensive analysis of the relevant variables (Appendix Fig. S2). Annual Mean Temperature (Bio1) emerged as the most influential variable, contributing 31.9% to the model, followed by slope (25%), elevation (13.9%), Mean Temperature of Wettest Quarter (Bio8) (12%), Precipitation of Driest Month (Bio14) (11.9%), and Precipitation of Warmest Month (Bio18) (5.3%). Permutation importance analysis confirmed these results, highlighting Bio14, elevation, and Bio8 as significant contributors, with slope maintaining its dominance at 25.4% (Fig. 2).
The habitat suitability analysis reveals significant shifts from the Last Glacial Maximum to the present and into future climate scenarios. From the Last Glacial Maximum to the Holocene, highly suitable habitats expanded significantly (+87.8%), with continued increases into the present (+13.5%), although unsuitable habitats remain dominant, occupying 81.22% of the area. Currently, highly suitable habitats account for only 7.61%, while moderately suitable and poorly suitable habitats cover 9.70% and 13.98%, respectively, reflecting the species' constrained optimal conditions. Future projections under different Shared Socioeconomic Pathways (SSPs) indicate substantial opportunities for habitat expansion, particularly under SSP126. By the 2040s, highly suitable habitats are projected to increase by 62.9%, with further gains of 117.0% by the 2070s. However, higher emissions scenarios (SSP585) suggest more habitat volatility, with gains in highly suitable habitats (+24.92%) offset by persistent unsuitable areas (53.09%) and risks of fragmentation (Fig. 3; Table 1). Moderately suitable habitats are also projected to decline under higher emissions scenarios, further challenging habitat stability and connectivity. These trends highlight a complex dynamic where habitat availability improves but environmental stability diminishes under higher emissions. This highlights the pressing need for targeted conservation strategies to address habitat fragmentation and ensure the species’ resilience to climate change.
| Period/scenario | Highly suitable (km2) | Change in highly suitable (%) | Moderately suitable (km2) | Change in moderately suitable (%) | Low suitable (km2) | Change in low suitable (%) | Unsuitable (km2) | Change in unsuitable (%) | Change (km2) | Change in total area (%) |
| Last Glacial Maximum | 43,340 | 6.5 | 37,365 | 5.38 | 49,653 | 7.15 | 563,088 | 81.22 | – | – |
| Holocene | 46,448 | 6.7 | 57,068 | 8.23 | 93,290 | 13.43 | 496,439 | 71.64 | 43,637 | 87.8 |
| Current | 52,751 | 7.61 | 67,357 | 9.7 | 96,974 | 13.98 | 476,364 | 68.71 | 3684 | 3.9 |
| 2040s, SSP126 | 85,952 | 12.66 | 66,593 | 9.8 | 86,558 | 12.75 | 440,289 | 64.79 | −764 | −1.1 |
| 2040s, SSP370 | 92,936 | 13.68 | 64,824 | 9.55 | 82,772 | 12.18 | 438,860 | 64.59 | −2533 | −3.8 |
| 2040s, SSP585 | 87,556 | 12.88 | 67,069 | 9.86 | 84,335 | 12.41 | 440,131 | 64.85 | −288 | −0.4 |
| 2070s, SSP126 | 115,708 | 17.03 | 74,864 | 11.01 | 79,564 | 11.7 | 409,256 | 60.26 | 7507 | 11.1 |
| 2070s, SSP370 | 139,205 | 20.5 | 73,512 | 10.81 | 74,600 | 10.96 | 392,075 | 57.73 | 6155 | 9.1 |
| 2070s, SSP585 | 169,427 | 24.92 | 65,120 | 9.59 | 84,311 | 12.41 | 360,534 | 53.09 | −2663 | −2.7 |
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Human activities continue to impose significant pressures on the Asian Houbara’s habitat, even in designated protected areas. The total area of highly suitable habitat for the species (52,751 km2) is extensively impacted by anthropogenic modifications, with 74.85% (39,478 km2) affected by human activities, such as infrastructure development, agricultural expansion, and urbanization. As a result, only 25.15% (13,273 km2) remains in a relatively undisturbed, natural state. Within protected areas, these pressures are also evident, with 27.23% (14,361 km2) of the suitable habitat compromised by human interventions, leaving only 6.08% (3205 km2) unaffected. Outside the protected areas, approximately 19.08% (10,068 km2) of highly suitable habitat remains free from anthropogenic activities, suggesting that substantial portions of critical habitat are still exposed to disturbances. Furthermore, nighttime light data, often associated with urbanization and population density, highlights another dimension of habitat degradation. About 76.63% (40,406 km2) of the suitable habitat coincides with areas of artificial lighting, which may indirectly affect the species by disrupting ecological processes or signaling anthropogenic activity. Within protected areas, 27.04% (14,260 km2) of the habitat is affected by artificial light pollution, leaving only 6.28% (3313 km2) in natural, dark conditions. Outside protected zones, artificial light pollution encroaches upon 49.68% (26,200 km2) of the habitat, with only 17.08% (9010 km2) remaining unaffected (Fig. 4).
Projected future dynamics for the Asian Houbara’s habitat exhibit significant variation across climate scenarios and time horizons (Fig. 5; Table 2). By the 2040s, under SSP126, 11.84% of the habitat is expected to be gained, with minimal loss (1.10%) and high stability (87.07%). In contrast, SSP370 predicts a slight increase in habitat gain (13.65%) but a marginal decline in stability (85.48%). SSP585 reflects similar trends, with habitat gain at 12.99%, though habitat loss rises to 1.86%, suggesting increased volatility. These patterns highlight the resilience of stable habitats under low emission scenarios but indicate growing pressures under high emission scenarios. By the 2070s, habitat gain intensifies across all scenarios. SSP126 projects a gain of 23.95%, with low habitat loss (0.23%) but reduced stability (75.82%). Under SSP370, habitat gain reaches 29.71%, accompanied by a further decline in stability (70.08%). SSP585 predicts the largest habitat gain (36.02%) but with significantly reduced stability (63.84%). The trends suggest that habitat gain accelerates under higher emissions but at the cost of increasing instability, potentially impacting habitat quality and connectivity. These findings indicate an overall expansion of suitable habitat but raise concerns about habitat fragmentation and declining stability. The trade-off between habitat availability and environmental integrity accentuates the need for proactive conservation strategies to mitigate fragmentation and ensure long term habitat sustainability.
| Scenario | Gain (area km2) | % age | Loss (area km2) | % age | Stable (area km2) | % age |
| 2040, SSP126 | 80,430 | 11.84 | 7440 | 1.0 | 591,523 | 87.07 |
| 2040, SSP370 | 92,732 | 13.65 | 5937 | 0.87 | 580,723 | 85.48 |
| 2040, SSP585 | 88,225 | 12.99 | 12,608 | 1.86 | 578,560 | 85.16 |
| 2070, SSP126 | 162,695 | 23.95 | 1550 | 0.23 | 515,148 | 75.82 |
| 2070, SSP370 | 201,872 | 29.71 | 1407 | 0.21 | 476,113 | 70.08 |
| 2070, SSP585 | 244,711 | 36.02 | 935 | 0.14 | 433,746 | 63.84 |
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The conservation gap analysis, conducted using ArcGIS 10.8, reveals a significant disparity between the highly suitable habitat for the Asian Houbara and the areas under protection. Of the 52,751 km2 of highly suitable habitat identified, only 2115 km2 lies within designated protected areas, leaving 50,636 km2 unprotected (Fig. 6). This limited overlap exposes vast portions of critical breeding and foraging habitats to threats. To mitigate this gap, efforts should prioritize expanding protected areas to encompass ecologically critical zones, with habitat restoration targeting degraded regions to enhance suitability. Community engagement must complement these actions, fostering sustainable land use practices and reducing anthropogenic pressures, ensuring long term habitat stability.
The distribution dynamics of the Asian Houbara in Pakistan’s deserts are intricately linked to climatic and geomorphological factors. Environmental variables such as annual mean temperature (Bio1) and slope have emerged as critical determinants of habitat suitability. Temperature not only affects metabolic and physiological processes but also dictates habitat preferences by influencing the availability of thermal refuges in arid environments. This pattern is consistent with studies that emphasize the role of microclimates in structuring desert ecosystems (Ma et al., 2023, Riddell et al., 2021). Moreover, the importance of slope in shaping the distribution of species in desert landscapes has been documented, as it often creates microhabitats with varied exposure to sunlight and wind, which are crucial for desert species' thermoregulation and resource access (Guisan et al., 2019). In addition, precipitation variables such as mean temperature of wettest quarter (Bio8) and precipitation of driest month (Bio14) play a significant role in determining suitable habitats for the Asian Houbara. In arid regions, where water is a limiting resource, species are closely tied to areas where even slight variations in precipitation can significantly affect resource availability and, subsequently, species survival. The reliance on specific climate patterns, especially in arid regions, is well documented, with species often confined to regions where precipitation and temperature remain within narrow ecological limits (Elsen et al., 2022; Gardner et al., 2022; Sumasgutner et al., 2023).
Projections for future habitat suitability based on climate models reveal potential changes in the spatial and temporal distribution of habitats. Under future climate scenarios, areas that are currently marginal or unsuitable may become viable, while others may be lost due to the increasing frequency and intensity of extreme weather events such as prolonged droughts (Yousefi et al., 2017; Monnier-Corbel et al., 2022; William et al., 2024a,b). This is consistent with global predictions for species in arid and semi-arid landscapes, where altered precipitation regimes and rising temperatures will create novel habitats, yet also exacerbate the risk of habitat fragmentation and degradation (Walther et al., 2002; Fordham et al., 2020). For the Asian Houbara, such shifts could present both opportunities and challenges. The expansion of suitable habitats under certain scenarios suggests potential gains, particularly in areas previously unsuitable due to temperature extremes. Similar habitat expansions have been observed in other desert bird species, where increasing temperatures push species into higher elevations or latitudes (Chen et al., 2011). However, the quality of these new habitats will be crucial for determining whether they can support viable populations. Habitat quality, which is often undermined by anthropogenic pressures such as overgrazing and land conversion, may limit the ability of the Asian Houbara to utilize these new areas (Qin et al., 2020; Shadloo et al., 2021; Shao et al., 2022).
This potential habitat expansion must also be viewed through the lens of connectivity. Desert landscapes are highly fragmented by both natural and human made barriers, limiting species' ability to move freely between suitable patches. Conservation strategies that promote connectivity, such as the creation of ecological corridors, will be essential in ensuring that the Asian Houbara can access new suitable areas as they emerge under future climate scenarios (Haddad et al., 2015; Keeley et al., 2018). The establishment of these corridors has been successful in other regions, providing critical pathways for species movement and genetic exchange in the face of habitat fragmentation (McGuire et al., 2016).
Anthropogenic threats, particularly habitat fragmentation and illegal hunting, remain formidable obstacles to the long term survival of the Asian Houbara in Pakistan. Habitat loss due to agricultural expansion, urbanization, and infrastructure development has significantly reduced the availability of suitable breeding and foraging grounds for the species (Lautenbach et al., 2021; Rather et al., 2021). Similar trends of habitat loss and fragmentation have been observed globally in arid regions, where large scale agricultural projects and resource extraction activities disrupt native ecosystems (Yuan et al., 2024). The direct removal of native vegetation, essential for providing food and shelter, compounds the species' vulnerability to environmental stressors. Moreover, the unsustainable hunting of the Asian Houbara, particularly for falconry in the Gulf States, continues to decimate populations, despite legal protections and international agreements (Hasui et al., 2024). Conservation interventions must therefore include stronger enforcement of existing regulations, along with international cooperation to address the transboundary nature of this threat (Zhang et al., 2023). Studies on other migratory species have shown that coordinated international efforts can be highly effective in reducing illegal trade and hunting pressures (Abedin et al., 2024). Engaging local communities in conservation efforts has also proven successful in reducing poaching, as seen in other arid landscapes (Koutchoro et al., 2024).
Gaps in the current network of protected areas pose another significant challenge. Our study reveals that a substantial portion of highly suitable habitat for the Asian Houbara lies outside of protected zones, exposing these critical areas to greater risk of degradation. This finding highlights the need for an expansion of protected areas or the implementation of conservation strategies that prioritize unprotected suitable habitats (Ahmadi et al., 2020; Wang et al., 2024). While the sample size used in this study is sufficient for broad-scale habitat predictions, as supported by our spatial filtering approach and model performance validation metrics, we acknowledge that a larger sample size would provide greater confidence for fine-scale or region specific conclusions. This limitation should be considered when interpreting the results, particularly for localized conservation applications. Future research incorporating additional occurrence data could improve the resolution and reliability of fine scale habitat models. The effectiveness of protected areas in conserving desert species has been demonstrated in several studies, where well managed reserves have successfully maintained viable populations even in the face of increasing anthropogenic pressures (Bosso et al., 2018; Yang et al., 2020).
The implications of climate change for the Asian Houbara highlight the urgency of adopting adaptive conservation strategies that take into account both current and future habitat projections. Climate driven shifts in habitat availability are expected to alter the species' range, necessitating a dynamic approach to conservation planning that incorporates the potential for future habitat gain, loss, and stability (Hardouin et al., 2015; William et al., 2024a,b). Studies have shown that proactive conservation measures, such as the identification and protection of climate refugia, can significantly improve species' resilience to climate change (Penteriani et al., 2019; Wilkening et al., 2019). Restoration of degraded habitats is another critical component of a long-term conservation strategy. Habitat restoration, when combined with the creation of ecological corridors, can enhance habitat connectivity and allow species to better adapt to shifting environmental conditions (Ashrafzadeh et al., 2020; Gregory et al., 2021). Furthermore, the restoration of native vegetation in degraded areas can enhance biodiversity, improve ecosystem services, and increase the resilience of desert ecosystems to climate change (Cheng et al., 2020; Chen and Costanza, 2024). Thus, it is essential to integrate local communities into conservation efforts. Community-based conservation initiatives have proven successful in other regions by fostering local stewardship and reducing human-wildlife conflict (Larson et al., 2016). Involving local stakeholders in the management and restoration of habitats can improve conservation outcomes while also providing economic benefits to local populations (Marshall et al., 2007; Karanth et al., 2018).
The findings of this study emphasize the critical need for a multifaceted approach to conserving the Asian Houbara in Pakistan’s deserts. Climate driven shifts in habitat suitability, combined with ongoing anthropogenic pressures, underscore the necessity of adaptive conservation strategies that incorporate both current and future habitat projections. The identification of key environmental variables, such as temperature, precipitation, and topographical features, provides essential insights into the species' habitat requirements. Conservation planning must prioritize the expansion of protected areas, restoration of degraded habitats, and the creation of ecological corridors to enhance connectivity and ensure the species' long term survival. As climate change reshapes the landscape, conservation strategies must be dynamic, incorporating future habitat projections and ensuring the protection of newly emerging suitable habitats. Addressing gaps in the current protected area network and mitigating anthropogenic threats, particularly habitat fragmentation and illegal hunting, will be critical. Finally, involving local communities in conservation efforts will be key to achieving sustainable conservation outcomes. By adopting an integrated and proactive approach, it is possible to safeguard the Asian Houbara and the biodiversity of Pakistan’s arid regions in the face of future environmental challenges.
Gulzaman William: Writing – original draft, Software, Methodology, Investigation, Conceptualization. Zafeer Saqib: Writing – review & editing, Supervision, Investigation, Formal analysis, Data curation. Abdul Qadir: Visualization, Supervision, Project administration, Formal analysis. Nisha Naeem: Validation, Resources, Investigation. Mehrban Ali Brohi: Supervision, Resources, Project administration, Investigation. Asim Kamran: Visualization, Supervision, Project administration, Investigation, Data curation. Afia Rafique: Validation, Resources, Data curation.
The authors declare no competing interests related to this study. There are no financial, personal, or professional conflicts that could influence the results or interpretation.
We would like to acknowledge the support of the Zoological Survey of Pakistan, and the Wildlife and Parks Department of Punjab for their assistance in this research. Their contributions were invaluable in facilitating our study on the Asian Houbara.
Supplementary data to this article can be found online at https://doi.org/10.1016/j.avrs.2024.100221.
Figures(6) / Tables(2)
| Period/scenario | Highly suitable (km2) | Change in highly suitable (%) | Moderately suitable (km2) | Change in moderately suitable (%) | Low suitable (km2) | Change in low suitable (%) | Unsuitable (km2) | Change in unsuitable (%) | Change (km2) | Change in total area (%) |
| Last Glacial Maximum | 43,340 | 6.5 | 37,365 | 5.38 | 49,653 | 7.15 | 563,088 | 81.22 | – | – |
| Holocene | 46,448 | 6.7 | 57,068 | 8.23 | 93,290 | 13.43 | 496,439 | 71.64 | 43,637 | 87.8 |
| Current | 52,751 | 7.61 | 67,357 | 9.7 | 96,974 | 13.98 | 476,364 | 68.71 | 3684 | 3.9 |
| 2040s, SSP126 | 85,952 | 12.66 | 66,593 | 9.8 | 86,558 | 12.75 | 440,289 | 64.79 | −764 | −1.1 |
| 2040s, SSP370 | 92,936 | 13.68 | 64,824 | 9.55 | 82,772 | 12.18 | 438,860 | 64.59 | −2533 | −3.8 |
| 2040s, SSP585 | 87,556 | 12.88 | 67,069 | 9.86 | 84,335 | 12.41 | 440,131 | 64.85 | −288 | −0.4 |
| 2070s, SSP126 | 115,708 | 17.03 | 74,864 | 11.01 | 79,564 | 11.7 | 409,256 | 60.26 | 7507 | 11.1 |
| 2070s, SSP370 | 139,205 | 20.5 | 73,512 | 10.81 | 74,600 | 10.96 | 392,075 | 57.73 | 6155 | 9.1 |
| 2070s, SSP585 | 169,427 | 24.92 | 65,120 | 9.59 | 84,311 | 12.41 | 360,534 | 53.09 | −2663 | −2.7 |
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| Scenario | Gain (area km2) | % age | Loss (area km2) | % age | Stable (area km2) | % age |
| 2040, SSP126 | 80,430 | 11.84 | 7440 | 1.0 | 591,523 | 87.07 |
| 2040, SSP370 | 92,732 | 13.65 | 5937 | 0.87 | 580,723 | 85.48 |
| 2040, SSP585 | 88,225 | 12.99 | 12,608 | 1.86 | 578,560 | 85.16 |
| 2070, SSP126 | 162,695 | 23.95 | 1550 | 0.23 | 515,148 | 75.82 |
| 2070, SSP370 | 201,872 | 29.71 | 1407 | 0.21 | 476,113 | 70.08 |
| 2070, SSP585 | 244,711 | 36.02 | 935 | 0.14 | 433,746 | 63.84 |
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