Widespread Population Decline Research Articles

Lampreys in California (Lampetra spp. and Entosphenus spp.): Mitochondrial phylogenetic analysis reveals previously unrecognized lamprey diversity

AbstractObjectiveProtecting biodiversity is important for preserving ecosystem functions and services, and understanding the diversity present in a system is necessary for effective conservation. Lampreys display extensive diversity in morphology and life history strategy. The extent of this diversity and the underlying genetic patterns have not yet been fully characterized. Uncertainty about species boundaries and operational taxonomic units hinders lamprey management and conservation. Limited data have been collected on California lampreys (Lampetra spp. and Entosphenus spp.), but evidence suggests widespread population decline across the west coast of North America. Study objectives were to identify which nominal species are present at study sites across northern and central California, determine whether current taxonomic classifications accurately and sufficiently describe lamprey diversity in California, and characterize the biogeographic distribution of genetically distinct lamprey lineages across the study area.MethodsTo achieve these objectives, this study utilized DNA barcoding, phylogenetic analysis, and species delimitation analysis. Lamprey individuals (N = 87) from 19 sites in the Sacramento–San Joaquin River basin, San Francisco Bay, and Klamath River basin were sequenced for the mitochondrial cytochrome b (cyt b) gene, and the data were combined with publicly available lamprey cyt b sequences for analysis.ResultResults showed relatively deep phylogenetic divergence between Lampetra and Entosphenus. Distinct and genetically divergent lineages were observed within Lampetra, while distinct but genetically similar lineages were observed within Entosphenus. This study revealed novel Lampetra lineages in the Napa River and Alameda Creek, and results suggest that the biogeographic distribution of lamprey diversity may follow patterns observed in other native fishes. Species delimitation results indicated that at least seven separate candidate species of Lampetra can be found in California, suggesting that California holds more species‐level diversity than the expected three nominal Lampetra species known to occur in the state.ConclusionThese results highlight the underestimated diversity of lampreys in California and the need for further assessment of taxonomic classifications and operational taxonomic unit designations of California lampreys.

A novel record of African wild dogs (Lycaon pictus) in Vwaza Marsh Wildlife Reserve, Malawi.

Most African wild dog (Lycaon pictus) populations are in decline and, due to habitat fragmentation and conflict rates in areas of higher anthropogenic land-use, are primarily restricted to protected areas. As a species that occurs at low densities, with a strict reproductive social structure, wild dogs rely on long-range dispersal to facilitate colonization, reproduction, and pack formation. In Malawi, large carnivores have been subject to widespread population decline and several protected areas have a reduced large carnivore guild, including the loss of resident wild dog populations. Here, during a biodiversity monitoring camera trap survey, we captured a novel record of wild dogs in Vwaza Marsh Wildlife Reserve (Vwaza), Malawi. The 11 photographic captures of potentially three individual wild dogs represent the first documented evidence of the species in Vwaza and the first record since an unconfirmed report in 2011. We hypothesize that this group of wild dogs moved into Vwaza through the Malawi-Zambia Transfrontier Conservation Area (MZTFCA), with the MZTFCA linking protected areas in Malawi with the Luangwa Valley, Zambia. The evidence provided here, and similar documentation in Kasungu National Park, Malawi, show that large carnivores can potentially move through the MZTFCA into protected areas in Malawi. We argue that the MZTFCA provides an important dispersal corridor that could help facilitate the recolonization of wild dogs, and other large carnivores, in Malawian protected areas. However, further research is needed to assess the permeability and status of the MZTFCA corridor into Malawi. We show that camera traps can be useful to document novel records of rare species and can be used to inform conservation management planning.

Amphibians and reptiles in North Sweden: distribution, habitat affinities, and abundance (Classes: Amphibia and Reptilia).

North Sweden ('Norrland' in Swedish) covers 243000 km2 and lies mainly in the boreal biome. The herpetofauna comprises five amphibian and four reptile species: Lissotriton vulgaris, Triturus cristatus, Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, Anguis fragilis, Natrix natrix, and Vipera berus. Successful conservation and management of amphibians and reptiles depend on accurate information about distribution, habitat affinities, and abundance. Such knowledge is also essential as a benchmark to assess changes in distribution and abundance that may come about as a result of climate change and human habitat alteration. This paper aims to present accurate distribution maps, describe habitat affinities, and provide abundance estimates for the herpetofauna of North Sweden for the period 1970-2022. Distribution data are presented by traditional faunistic provinces, as well as by biotic regions and alpine life zones. Separate sections address post-glacial colonization and a herpetological perspective on anthropogenic changes in relation to species´ present status. Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, and Vipera berus are widely distributed throughout the boreal sub-regions. Rana temporaria, Zootoca vivipara, and Vipera berus also extend into the alpine region. Triturus cristatus, Anguis fragilis, and Natrix natrix occur mainly in the coastal parts of the Southern Boreal region. There are no signs of recent changes in distribution range, but Lissotriton vulgaris, Triturus cristatus, and Rana arvalis have been largely overlooked in the past and have a much wider occurrence than previously recognized. Most species are found in habitats usually not described in all-European field guides. Nearly all anurans hibernate in water. Abundance estimates suggest that some species are more common in the boreal than thought, supporting the notion that a large share of their total European population occurs there. Although local extinctions and declines are known, there are no signs of widespread population decline for any species during the study period.

Use of environmental DNA to assess American Eel distribution, abundance, and barriers in a river–canal system

AbstractObjectiveThe American Eel Anguilla rostrata historically was one of the most common fish species in Atlantic coast watersheds, but extensive dam construction and other factors caused a widespread population decline. One of the watersheds where American Eels have declined considerably is the Mohawk River in eastern and central New York. Recent attempts to characterize the distribution and abundance of American Eels in this watershed have been ineffective, and the extent to which a series of locks and dams on the Hudson River and lower Mohawk River limits use of the watershed is unclear.MethodsWe developed a model between environmental DNA (eDNA) quantity and American Eel abundance in the Hudson River watershed in which the DNA concentration in water samples explained up to 65% of the variability in eel density and 56% of the variability in eel biomass. We then used this relationship to interpret eDNA data collected twice from 36 sites across the Mohawk River watershed in 2021 and make inferences about the distribution and abundance of American Eels.ResultAmerican Eel DNA was detected almost exclusively in the downstream‐most 4 km of the Mohawk River within a series of barriers. The concentration of DNA was reduced by approximately 80% across each successive upstream barrier before becoming too low to detect consistently. Our data suggest that eel population density was high in the Hudson River estuary and declined rapidly in the lower Mohawk River, and the species was nearly absent or undetectable in the Mohawk River and its tributaries upstream of the Crescent Dam and the Waterford Flight of Locks.ConclusionBarriers appear to be largely restricting American Eels from using over 99% of the Mohawk River watershed. Therefore, improvements in fish passage at dams and hydroelectric facilities in the region could help the American Eel to regain access to this part of its native range.

Population genomics and conservation management of the threatened black-footed tree-rat (Mesembriomys gouldii) in northern Australia

Genomic diversity is a fundamental component of Earth’s total biodiversity, and requires explicit consideration in efforts to conserve biodiversity. To conserve genomic diversity, it is necessary to measure its spatial distribution, and quantify the contribution that any intraspecific evolutionary lineages make to overall genomic diversity. Here, we describe the range-wide population genomic structure of a threatened Australian rodent, the black-footed tree-rat (Mesembriomys gouldii), aiming to provide insight into the timing and extent of population declines across a large region with a dearth of long-term monitoring data. By estimating recent trajectories in effective population sizes at four localities, we confirm widespread population decline across the species’ range, but find that the population in the peri-urban area of the Darwin region has been more stable. Based on current sampling, the Melville Island population made the greatest contribution to overall allelic richness of the species, and the prioritisation analysis suggested that conservation of the Darwin and Cobourg Peninsula populations would be the most cost-effective scenario to retain more than 90% of all alleles. Our results broadly confirm current sub-specific taxonomy, and provide crucial data on the spatial distribution of genomic diversity to help prioritise limited conservation resources. Along with additional sampling and genomic analysis from the far eastern and western edges of the black-footed tree-rat distribution, we suggest a range of conservation and research priorities that could help improve black-footed tree-rat population trajectories at large and fine spatial scales, including the retention and expansion of structurally complex habitat patches.

Invasion of annual grasses following wildfire corresponds to maladaptive habitat selection by a sagebrush ecosystem indicator species

Numerous wildlife species within semi-arid shrubland ecosystems across western North America are experiencing substantial habitat loss and fragmentation. These changes in habitat are often attributed to a diverse suite of factors including prolonged and increasingly severe droughts, conifer expansion, anthropogenic development, domestic and feral livestock grazing, and invasion of exotic annual grasses, which promotes increased wildfire frequency and severity. Greater sage-grouse ( Centrocercus urophasianus ; hereafter, sage-grouse) are considered an indicator of sagebrush ecosystem health and have experienced widespread population decline associated with habitat loss and degradation, as well as changes in predator communities. Our objectives were to model and map sage-grouse habitat selection and survival during the important brood-rearing life stage in relation to landscape-scale environmental predictors. Furthermore, we sought to understand impacts of wildfire and annual grass invasion on brood habitat, as these accelerated disturbance regimes are a primary cause of habitat loss within the Great Basin region of the USA. We used a hierarchical Bayesian modeling framework to estimate resource selection functions and survival for early and late brood-rearing stages of sage-grouse in relation to a broad suite of habitat characteristics evaluated at multiple spatial scales within the Great Basin from 2009 to 2019. Sage-grouse selected for greater perennial grass cover, higher relative elevations, and areas closer to springs and wet meadows during both early and late brood-rearing. Terrain characteristics, including heat load and aspect, were important in survival models, as was variation in shrub height. We also found strong evidence for higher survival for both early and late broods within previously burned areas, but survival within burned areas decreased as annual grass cover (i.e. cheatgrass, Bromus tectorum ) increased. This interaction effect demonstrates how invasion of annual grasses into burned areas, which has become prevalent in Great Basin sagebrush ecosystems, can lead to maladaptive habitat selection by brood-rearing greater sage-grouse. Understanding these complex relationships aids wildlife conservation and habitat management as wildfire and annual grass cycles continue to accelerate across western ecosystems.

Social media and citizen science records are important for the management of rarely sighted whales

Social media content is increasingly being validated and used as a valuable source of data within conservation science. Metadata obtained from social networking sites (SNS) can supplement knowledge and data gaps in traditional ecological monitoring programs by increasing the spatiotemporal extent of sampling. Here we consider SNS in the context of rare and threatened species, which are difficult to monitor due to their often-inaccessible habitat, or elusive and unpredictable occurrences. We focus on a recovering large whale population, as charismatic megafauna often appear on SNS and are ideal for public outreach sightings data. Southern right whales (Eubalaena australis, SRW) were once abundant throughout New Zealand waters. However, following widespread population decline during whaling, no SRW was reported around the mainland for 35 years, with the remnant population persisting only in the remote subantarctic islands. By using sightings data from 2011 to 2021 in the New Zealand Department of Conservation's (DOC) Marine Mammal Database and supplementing with crowd-sourced sightings reports made on SNS (Facebook and iNaturalist), we present evidence that SRWs are continuing to recover slowly around the mainland compared to their subantarctic breeding grounds. All sightings' data were categorised based on confidence of accuracy, for example, accompanying genetic or photographic confirmation of species identity. Sightings remain rare with only 116 sightings from both DOC and SNS sources reported over the 11-year research period (2011–2021), hindering efforts to identify key habitats and implement conservation measures. SNS sightings increased the overall number and quality of sightings. Specifically, as SNS sightings were all accompanied by images permitting confident species ID, they increased the overall quality of the dataset and provided new information on the fine-scale movement and residency times of SRW. Although opportunistic data such as these have limitations, our work suggests that the recolonisation of SRWs around mainland New Zealand has not increased in the past decade. This could reflect historic loss of matrilineal knowledge of the mainland, or it could also be an artifact of very few whales, resulting in less social aggregations frequenting the region. Citizen science and the use of SNS data are important for the continued monitoring of the New Zealand SRW population, with SNS data creating further opportunities to monitor similarly rare and data deficient populations.

ДЕМОГРАФИЧЕСКАЯ КОМПОНЕНТА ФОРМИРОВАНИЯ ЧЕЛОВЕЧЕСКОГО КАПИТАЛА ДЛЯ УСТОЙЧИВОГО РАЗВИТИЯ РЕГИОНОВ

Abstract. The role of the demographic component in the formation of the human capital of the regions is considered. On the example of the North-Western Federal District, the modern dominant trends of demographic processes are revealed. The main demographic challenges in the conditions of widespread population decline for the sustainable development of the regions are identified.

Estimating widespread beaver dam loss: Habitat decline and surface storage loss at a regional scale

AbstractThe loss of beaver populations has commonly been accompanied by the failure of beaver dams, leading to stream incision, water table lowering, and the eventual transition from a beaver meadow to a drier riparian corridor. Widespread decline in North American beaver populations (Castor canadensis) has been documented from pre‐European settlement to the current day, representing an estimated 80% to 98% loss of historical populations. While individual case studies have investigated the ecosystem impacts of local beaver population loss, few studies have quantified large‐scale changes associated with widespread population decline. Here, we use the Beaver Restoration Assessment Tool to model landscape‐scale habitat suitability and beaver dam capacity in Colorado, USA, in order to determine whether a widespread loss in beaver population corresponds to a similar scale decline in the capacity to sustain beaver on the landscape and declines in physical benefits associated with beaver, such as surface water and sediment storage. Currently, the statewide stream network (298,119 stream kilometers) can support approximately 1.36 million beaver dams, compared with 2.39 million dams historically. All regions of Colorado have seen a decline in beaver dam capacity from historical conditions, likely due to agriculture, urbanization, and loss of vegetation necessary to beaver. Beaver dam capacity loss is accompanied by an approximate 40% decline in beaver‐mediated surface water and sediment storage potential across the state. Regions with high percent loss in storage potentials also had a high percentage of drainage network that had experienced beaver dam capacity losses of 15 or more dams per kilometer, which highlights the disproportionate impacts of losing high dam density reaches (i.e., beaver meadows). Extreme dam density declines were rare, and instead, most reaches have undergone a shift from high to moderate capacity. Statewide shifts in beaver dam capacity highlight the opportunity for using beaver‐related restoration in Colorado and across the American West.

Role of the Summer Monsoon Variability in the Collapse of the Ming Dynasty: Evidences From Speleothem Records

AbstractClimatic changes have played an important role in societal reorganizations. Particularly, the late 16th and early 17th century coincided with severely cold condition, extremely weak summer monsoon and widespread population decline in China. Here we present new speleothem oxygen isotope records across North and South China, which in concert with historical documents, allow us to characterize the “Late Ming Weak Monsoon Periods” (LMWMP) at an unprecedented annual temporal resolution. Our analysis suggests that as a weak summer monsoon event not seen for nearly 500 years in China, the LMWMP spatiotemporally coincided with the late Ming Dynasty peasant uprising (1627–1658 CE), and thus the transition from Ming to Qing Dynasty. This suggests a plausible role of climate change in shaping the important chapters of the Chinese history. In addition, both speleothem and historical documents reveal that the LMWMP appears to be a north to south time‐transgressive event on decadal‐timescale.

Direct evidence of poison-driven widespread population decline in a wild vertebrate

Toxicants such as organochlorine insecticides, lead ammunition, and veterinary drugs have caused severe wildlife poisoning, pushing the populations of several apex species to the edge of extinction. These prime cases epitomize the serious threat that wildlife poisoning poses to biodiversity. Much of the evidence on population effects of wildlife poisoning rests on assessments conducted at an individual level, from which population-level effects are inferred. Contrastingly, we demonstrate a straightforward relationship between poison-induced individual mortality and population changes in the threatened red kite (Milvus milvus). By linking field data of 1,075 poisoned red kites to changes in occupancy and abundance across 274 sites (10 × 10-km squares) over a 20-y time frame, we show a clear relationship between red kite poisoning and the decline of its breeding population in Spain, including local extinctions. Our results further support the species listing as endangered, after a breeding population decline of 31% to 43% in two decades of this once-abundant raptor. Given that poisoning threatens the global populations of more than 2,600 animal species worldwide, a greater understanding of its population-level effects may aid biodiversity conservation through increased regulatory control of chemical substances. Our results illustrate the great potential of long-term and large-scale on-ground monitoring to assist in this task.

Genomic signatures and correlates of widespread population declines in salmon

Global losses of biodiversity are occurring at an unprecedented rate, but causes are often unidentified. Genomic data provide an opportunity to isolate drivers of change and even predict future vulnerabilities. Atlantic salmon (Salmo salar) populations have declined range-wide, but factors responsible are poorly understood. Here, we reconstruct changes in effective population size (Ne) in recent decades for 172 range-wide populations using a linkage-based method. Across the North Atlantic, Ne has significantly declined in >60% of populations and declines are consistently temperature-associated. We identify significant polygenic associations with decline, involving genomic regions related to metabolic, developmental, and physiological processes. These regions exhibit changes in presumably adaptive diversity in declining populations consistent with contemporary shifts in body size and phenology. Genomic signatures of widespread population decline and associated risk scores allow direct and potentially predictive links between population fitness and genotype, highlighting the power of genomic resources to assess population vulnerability.

Widespread population decline in South America correlates with mid-Holocene climate change

Quantifying the impacts of climate change on prehistoric demography is crucial for understanding the adaptive pathways taken by human populations. Archaeologists across South America have pointed to patterns of regional abandonment during the Middle Holocene (8200 to 4200 cal BP) as evidence of sensitivity to shifts in hydroclimate over this period. We develop a unified approach to investigate demography and climate in South America and aim to clarify the extent to which evidence of local anthropic responses can be generalised to large-scale trends. We achieve this by integrating archaeological radiocarbon data and palaeoclimatic time series to show that population decline occurred coeval with the transition to the initial mid-Holocene across South America. Through the analysis of radiocarbon dates with Monte Carlo methods, we find multiple, sustained phases of downturn associated to periods of high climatic variability. A likely driver of the duration and severity of demographic turnover is the frequency of exceptional climatic events, rather than the absolute magnitude of change. Unpredictable levels of tropical precipitation had sustained negative impacts on pre-Columbian populations lasting until at least 6000 cal BP, after which recovery is evident. Our results support the inference that a demographic regime shift in the second half of the Middle Holocene were coeval with cultural practices surrounding Neotropical plant management and early cultivation, possibly acting as buffers when the wild resource base was in flux.

The Male-Produced Aggregation-Sex Pheromone of the Cerambycid Beetle Plagionotus detritus ssp. detritus

The number of longhorn beetles with confirmed aggregation-sex pheromones has increased rapidly in recent years. However, the species that have been studied most intensively are pests, whereas much less is known about the pheromones of longhorn beetles that are rare or threatened. We studied the cerambycid beetle Plagionotus detritus ssp. detritus with the goal of confirming the presence and composition of an aggregation-sex pheromone. This species has suffered widespread population decline due to habitat loss in Western Europe, and it is now considered threatened and near extinction in several countries. Beetles from a captive breeding program in Sweden were used for headspace sampling. Gas chromatography-mass spectrometry revealed that collections from males contained large quantities of two compounds, identified as (R)-3-hydroxy-2-hexanone (major component) and (S)-2-hydroxy-3-octanone (minor component), in addition to smaller quantities of 2,3-hexanedione and 2,3-octanedione. None of the compounds was present in collections from females. When tested singly in a field bioassay, racemic 3-hydroxy-2-hexanone and 2-hydroxy-3-octanone were not attractive to P. detritus, whereas a 5:1 blend elicited significant attraction. Both compounds are known as components of the pheromones of conspecific beetles, but, to our knowledge, this is the first cerambycid shown to use two compounds with different chain lengths, in which the positions of the hydroxyl and carbonyl functions are interchanged between the two. The pheromone has potential as an efficient tool to detect and monitor populations of P. detritus, and may also be useful in more complex studies on the ecology and conservation requirements of this species.

Movements of female Sage Grouse Centrocercus urophasianus during incubation recess

We combined GPS data‐loggers, VHF transmitters and DVR video‐monitoring to measure fine‐scale movement patterns during daily incubation recesses by female Sage Grouse Centrocercus urophasianus, a species with uniparental incubation that has experienced widespread population decline and distributional contraction. Most (69.6%) Sage Grouse recess activity was highly localized within a core recess area averaging 2.58 ± 0.64 ha, and females remained within 242.3 ± 30.0 m from the nest during recesses (total recess areas were 11.06 ± 2.27 ha). Visually conspicuous Sage Grouse movements near nests at the start and end of recesses and consistent occupation of core recess areas point to a mechanism for newly abundant predators such as the Northern Raven Corvus corax to detect and depredate Sage Grouse nests. Our methods apply to other avian species of scientific interest and conservation concern.

Widespread, episodic decline of alder (Alnus) during the medieval period in the boreal forest of Europe

ABSTRACTWe report pollen‐stratigraphical evidence for an abrupt, episodic and widespread population decline of alder (Alnus), one of the most common boreal tree genera, during the medieval period in northern Europe. Decline of alder pollen values was observed both in forest hollow pollen records reflecting local vegetation of pristine forests and in pollen percentage and pollen accumulation data from lake sediments. The event began roughly at AD 600 and the recovery took place at AD 1000. Human impact is an unlikely cause because the decline is specific to alder and there is no evidence for a concurrent episode of human impact. It is possible that the decline was caused or influenced by a severe drought. Another potential cause is a sudden, widespread pathogen outbreak, especially as alder is known to be sensitive to the impacts of fungal pathogens such as the oomycete Phytophthora.

Pesticide toxicity and avifauna of Punjab

Use of pesticides, in modern agriculture has increased tremendously. Pesticides affect the human, environment and wildlife including birds. Three main groups of chemical synthetic pesticides are organochlorine, organophosphate and carbamate. Because of persistent nature, organochlorine are no longer in use in several countries. But some of them like aldrin, dieldrin, lindane and endosulfan are still in use in developing countries. They cause widespread population decline of raptorial birds like the peregrine falcon, the sparrow hawk and bald eagle. The well known effect of DDT in eggshell thinning of the peregrine falcon is caused by its highly persistent metabolite DDE [1,1, bis-4-chlorphenyl]-2,2 dichlorethylene]. Organophosphate and carbamate insecticides do not bioaccumulate in the food chains and are less persistent. They have replaced the more persistent organochlorines. This communication elaborates the effect of synthetic chemical pesticides on birds along with a note on policy framework on use of pesticides.

The freshwater ostracod (Crustacea) genus Notodromas Lilljeborg, 1853 (Notodromadidae) from Japan; taxonomy, ecology and lifestyle.

Although Notodromas monacha (O. F. Müller, 1776) was first reported from Japan over 85 years ago, detailed comparisons between Japanese and European specimens reveal that the Japanese specimens have been misidentified. The Japanese specimens are described as a new species, Notodromas trulla n. sp., herein. This species differs from Notodromas monacha by the morphology of the male fifth limbs and sexual organs, and the morphology of the female carapace. Like other Notodromas species, it is at least partially neustonic, spending considerable amounts of time hanging upside down from the water surface, facilitated by an oval concavity on its ventral surface. It is found in rice fields and small, shallow ponds with few or no floating plants and a muddy substrate, and in suitable habitats can be very abundant. However, evidence suggests that this conspicuous species has experienced a significant and widespread population decline in Japan; reported as abundant in rice fields, swamps and ponds in the 1940s-70s, this species has been collected from only a small number of localities in recent years.

Population Size, Survival, Growth, and Movements ofRana sierrae

Abstract: Based on 2431 captures of 757 individual frogs over a 9-yr period, we found that the population of R. sierrae in one meadow–stream complex in Yosemite National Park ranged from an estimated 45 to 115 adult frogs. Rana sierrae at our relatively low elevation site (2200 m) grew at a fast rate (K = 0.73–0.78), had high overwintering survival rates (44.6–95%), lived a long time (up to 16 yr), and tended to be fairly sedentary during the summer (100% minimum convex polygon annual home ranges of 139 m2) but had low year-to-year site fidelity. Even though the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) has been present in the population for at least 13 yr, there was no clear downward trend as might be expected from reports of R. sierrae population declines associated with Bd or from reports of widespread population decline of R. sierrae throughout its range.

Constraints on home range behaviour affect nutritional condition in urban house sparrows (Passer domesticus)

In human-dominated landscapes (semi)natural habitats are typically embedded in tracts of unsuitable habitat. Under such conditions, habitat characteristics and grain size of the surrounding landscape may affect how much food, and at what cost, is available for sedentary species with low home-range plasticity. Here we combine behavioural radio-tracking, feather ptilochronology, and landscape analysis to test how nutritional condition varies with home range size in 13 house sparrow [Passer domesticus (Linnaeus, 1758)] populations along an urban gradient. Urban individuals occupied smaller home ranges than conspecifics from rural areas, most distinctly if key cover was highly scattered. In urban plots, patch connectivity, home range sizes, and activity areas were positively correlated, indicating that individual ranging behaviour was related to the spatial distribution of suitable habitat. Urban House sparrows also showed the smallest feather growth bars, which were positively related to home range size at plot level. In contrast, growth bar widths and home range sizes were negatively related in rural populations, whereas in suburban populations, both variables varied independently. We conclude that individuals from progressively more built-up areas show a restricted ability to adjust their daily ranging behaviour to the scattered distribution of critical resources. This may complement other putative causes of the widespread population decline of urban house sparrows. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 41–50.