Flexible Habitat Research Articles

Landscape context and behavioral clustering contribute to flexible habitat selection strategies in a large mammal

Landscape context and behavioral clustering contribute to flexible habitat selection strategies in a large mammal

Genetic diversity and connectivity of the Irrawaddy dolphin in Southern Thailand: Emphasizing the last fourteen of the Songkhla dolphin status from a microsatellite perspective

Abstract. Budi T, Ninwat S, Sakornwimon W, Thongcham K, Phakphien R, Kalaya C, Phavaphutanon J. 2024. Genetic diversity and connectivity of the Irrawaddy dolphin in Southern Thailand: Emphasizing the last fourteen of the Songkhla dolphin status from a microsatellite perspective. Biodiversitas 25: 1729-1735. Irrawaddy dolphin (Orcaella brevirostris Gray, 1866) can be found in diverse aquatic environments, ranging from coastal to brackish water, stretching from the West of Bengal in India to the central part of the Indonesian archipelago. Despite its widespread distribution and flexible habitat tolerance, Irrawaddy dolphins in Songkhla Lake, Southern Thailand, are hypothesized to be isolated and exhibit concerningly low population numbers, threatening their long-term survival. Limited knowledge exists regarding their population genetics status. This study analyzed 30 samples from Songkhla Lake (SKL) and the Lower Gulf of Thailand (LGT) to assess their genetic diversity, structure, and connectivity using 16 microsatellite loci. Extremely low genetic diversity was observed in SKL (Ho = 0.039±0.039; AR = 1.122±0.489) and LGT (Ho = 0.033±0.033; AR = 1.141±0.566) populations. Population differentiation (FST = 0.033, p>0.05) and clustering analyses based on both Principal Coordinate Analysis (PCoA) and Discriminant Analysis of Principal Component (DAPC) suggest limited genetic divergence and potential panmixia (single genetic pool) between both populations. These findings highlight critical conservation concerns due to low diversity despite the lack of isolation, emphasizing the need for immediate and targeted efforts to ensure the long-term viability of this iconic yet vulnerable population.

Living on the Forest Edge: Flexible Habitat Use in Sedentary Pied Flycatchers Ficedula Hypoleuca during the Non-Breeding Season

Living on the Forest Edge: Flexible Habitat Use in Sedentary Pied Flycatchers Ficedula Hypoleuca during the Non-Breeding Season

Pampas fox spatial and temporal variation in Argentinean agroecosystems

Context Agricultural activities have reduced wildlife natural habitats and increased the spatial overlap between animals’ distribution and human activities. However, carnivores with a broad diet and flexible habitat requirements can tolerate human-induced environmental changes. Thus, identifying changes in their densities and spatial distribution are important factors to take into consideration when working towards minimising human–carnivore conflict. Aims Our aim was to identify the main environmental and human variables influencing Pampas fox density and to produce density maps in the reproductive and non-reproductive seasons. Methods We performed spotlight counts at night, following the line transect method in the non-reproductive and reproductive seasons during two consecutive years. We also obtained landscape, human-impact and environmental spatial variables using remote sensing data and Geographic Information Systems. We modelled and mapped the Pampas fox’s spatial density using Density Surface Models. Key results We found that disturbance by human activities and landscape configuration influenced the spatial variation of the Pampas fox density across time and space. We registered a positive association between the number of foxes and the proximity to urban areas and paved roads, and we also found higher densities near grasslands areas and less modified habitats varying with the season and year. A higher density of foxes was observed in the non-reproductive season compared with the reproductive season. Conclusions and Implications This study provides insight on the variation in Pampas fox densities across agroecosystems. It highlights the relevance of more naturalised and protected habitats to sustain the Pampas fox population in highly fragmented landscapes, but also shows a positive association with disturbed areas. The spatial information developed in this study is useful to identify areas where ecosystem services could be encouraged, helping to maintain the ecosystems’ equilibrium and biodiversity conservation, and develop new management programs creating human–wildlife coexistence.

The invasion of tilapia in South China freshwater systems: A review

AbstractTilapia invasion has become a significant concern to ecologists and conservationists, posing severe threat to freshwater biodiversity. Many tilapia species have been introduced to China since 1957, with some having invaded freshwater ecosystems in South China. Accordingly, the present review examined the driving factors for successful tilapia invasion and their ecological impacts, information essential for practical management purposes. This review identified aquaculture as the main pathway spreading tilapias into the wild freshwater systems through their escape and release. Their biological and life history traits, including flexible habitat requirements, environmental tolerance, and generalist feeding are essential factors facilitating their ability to inhabit varying habitats. Biodiversity loss and habitat degradation further promote tilapia invasions by creating exploitable habitats for them, noting their considerable tolerance to degraded ecosystems. Regarding ecological effects, tilapias stimulate phytoplankton growth by increasing nutrient concentrations in the water column through excretion and bioturbation. Tilapias also depress benthic algal growth by promoting sediment resuspension, deteriorating water quality, and enhancing eutrophication. Moreover, tilapias cause the decline of native fish species biomass through competition and may threaten fish biodiversity. The findings in the present review suggest direct removal of tilapias can be a useful practice for controlling them. Furthermore, imposing regulations on tilapias introductions, efficient aquaculture management, and biodiversity conservation should also be considered in controlling and preventing the invasion and spread of tilapias.

Correction to: 'A triple threat: high population density, high foraging intensity and flexible habitat preferences explain high impact of feral cats on prey' (2021) by Hamer et al.

Correction to: 'A triple threat: high population density, high foraging intensity and flexible habitat preferences explain high impact of feral cats on prey' (2021) by Hamer et al.

Flexible habitat choice of pelagic bacteria increases system stability and energy flow through the microbial loop

AbstractPelagic bacteria can be classified into free‐living and particle‐attached life modes, which either dwell in the water column or attach to suspended particles. Bacteria with a generalist life style, however, can actively shift between these two habitats. Globally increasing densities of natural and artificial particles enhance habitat heterogeneity, with potential consequences for system stability and trophic transfer through aquatic food webs. To better decipher the dynamics of microbial communities, we investigated the influence of adaptive vs. fixed habitat choice on species coexistence for a simplified bacterial community by analyzing a corresponding food web model, consisting of two specialist bacterial prey species (free and attached), a generalist bacterial prey species with the ability to shift between both habitats, and two protist predators, specialized on either water or particle compartment. For simplicity we assume a shared resource pool, considering particles only for colonization but not as a source for nutrients or carbon, that is, inert particles like microplastics or inorganic sediments. The model predicts coexistence on a cyclic attractor between fixed and flexible bacteria, if the costs for adaptive habitat choice can be balanced by adaptation speed. The presence of adaptive prey dampens predator–prey cycle amplitudes, contributing to system stabilization resulting in higher mean predator biomass compared to specialist prey only. Thus, in pelagic microbial systems, flexible habitat choice at the prey level has important implications for system stability and magnitude of energy flow through the microbial loop.

Hydrodynamic disturbance controls microbial community assembly and biogeochemical processes in coastal sediments

The microbial community composition and biogeochemical dynamics of coastal permeable (sand) sediments differs from cohesive (mud) sediments. Tide- and wave-driven hydrodynamic disturbance causes spatiotemporal variations in oxygen levels, which select for microbial generalists and disrupt redox cascades. In this work, we profiled microbial communities and biogeochemical dynamics in sediment profiles from three sites varying in their exposure to hydrodynamic disturbance. Strong variations in sediment geochemistry, biogeochemical activities, and microbial abundance, composition, and capabilities were observed between the sites. Most of these variations, except for microbial abundance and diversity, significantly correlated with the relative disturbance level of each sample. In line with previous findings, metabolically flexible habitat generalists (e.g., Flavobacteriaceae, Woeseaiceae, Rhodobacteraceae) dominated in all samples. However, we present evidence that aerobic specialists such as ammonia-oxidizing archaea (Nitrosopumilaceae) were more abundant and active in more disturbed samples, whereas bacteria capable of sulfate reduction (e.g., uncultured Desulfobacterales), dissimilatory nitrate reduction to ammonium (DNRA; e.g., Ignavibacteriaceae), and sulfide-dependent chemolithoautotrophy (e.g., Sulfurovaceae) were enriched and active in less disturbed samples. These findings are supported by insights from nine deeply sequenced metagenomes and 169 derived metagenome-assembled genomes. Altogether, these findings suggest that hydrodynamic disturbance is a critical factor controlling microbial community assembly and biogeochemical processes in coastal sediments. Moreover, they strengthen our understanding of the relationships between microbial composition and biogeochemical processes in these unique environments.

Metabolic flexibility allows bacterial habitat generalists to become dominant in a frequently disturbed ecosystem

Ecological theory suggests that habitat disturbance differentially influences distributions of habitat generalist and specialist species. While well-established for macroorganisms, this theory has rarely been explored for microorganisms. Here we tested these principles in permeable (sandy) sediments, ecosystems with much spatiotemporal variation in resource availability and physicochemical conditions. Microbial community composition and function were profiled in intertidal and subtidal sediments using 16S rRNA gene amplicon sequencing and metagenomics, yielding 135 metagenome-assembled genomes. Community composition and metabolic traits modestly varied with sediment depth and sampling date. Several taxa were highly abundant and prevalent in all samples, including within the orders Woeseiales and Flavobacteriales, and classified as habitat generalists; genome reconstructions indicate these taxa are highly metabolically flexible facultative anaerobes and adapt to resource variability by using different electron donors and acceptors. In contrast, obligately anaerobic taxa such as sulfate reducers and candidate lineage MBNT15 were less abundant overall and only thrived in more stable deeper sediments. We substantiated these findings by measuring three metabolic processes in these sediments; whereas the habitat generalist-associated processes of sulfide oxidation and fermentation occurred rapidly at all depths, the specialist-associated process of sulfate reduction was restricted to deeper sediments. A manipulative experiment also confirmed habitat generalists outcompete specialist taxa during simulated habitat disturbance. Together, these findings show metabolically flexible habitat generalists become dominant in highly dynamic environments, whereas metabolically constrained specialists are restricted to narrower niches. Thus, an ecological theory describing distribution patterns for macroorganisms likely extends to microorganisms. Such findings have broad ecological and biogeochemical ramifications.

Flexible habitat choice by aphids exposed to multiple cues reflecting present and future benefits

Abstract Mothers choose suitable habitats for laying offspring to maximize fitness. Because habitat quality varies in space and time, mothers gather information to choose among available habitats through multiple cues reflecting different aspects of habitat quality at present and in the future. However, it is unclear how females assess and integrate different cues associated with current rewards and future safety to optimize oviposition/larviposition decisions, especially across small spatial scales. Here, we tested the individual and interactive effects of leaf surface, leaf orientation, and leaf bending direction on larviposition site choice and fitness benefits of wheat aphids (Metopolophium dirhodum) within individual leaves. We found that females preferred upper over lower surfaces for gaining current food-related rewards, downward- over upward-facing surfaces for avoiding potential abiotic risks, and sunken over protruding surfaces for avoiding potential biotic risks. When facing conflicting cues during larviposition, females preferred downward-facing/sunken surfaces over upper surfaces, suggesting that females prioritize potential safety at the cost of current rewards during decision making. Most importantly, our combined-cue experiments showed females still assessed secondary cues (i.e., the upper surface) when first-ranked cues (i.e., the downward-facing/sunken surface) are available, even though females only gained relatively small fitness rewards through secondary cues, and females can integrate different cues associated with current rewards and potential safety in a multiplicative way to make flexible and complex larviposition decisions. Overall, our findings provide new insights into how animals collect and process multi-cue information associated with current rewards and potential safety to maximize fitness at small spatial scales.

A triple threat: high population density, high foraging intensity and flexible habitat preferences explain high impact of feral cats on prey.

Alien mammalian carnivores have contributed disproportionately to global loss of biodiversity. In Australia, predation by the feral cat and red fox is one of the most significant causes of the decline of native vertebrates. To discover why cats have greater impacts on prey than native predators, we compared the ecology of the feral cat to a marsupial counterpart, the spotted-tailed quoll. Individual prey are 20-200 times more likely to encounter feral cats, because of the combined effects of cats' higher population densities, greater intensity of home-range use and broader habitat preferences. These characteristics also mean that the costs to the prey of adopting anti-predator behaviours against feral cats are likely to be much higher than adopting such behaviours in response to spotted-tailed quolls, due to the reliability and ubiquity of feral cat cues. These results help explain the devastating impacts of cats on wildlife in Australia and other parts of the world.

The effect of vegetation structure on seasonal density of Sylvia warblers in the eastern Iberian Peninsula

ABSTRACT Capsule Vegetation characteristics determine seasonal habitat selection by Eurasian Blackcaps Sylvia atricapilla, Dartford Warblers Sylvia undata, and Sardinian Warblers Sylvia melanocephala, and changes in these characteristics affect the structure of bird communities. Aims To evaluate the effect of vegetation structure on the seasonal density of Sylvia warblers in the eastern Iberian Peninsula. Methods During spring 2015 and winter 2015/16, we carried out linear transects in natural and agricultural habitats to quantify the presence of three warbler species: Eurasian Blackcap, Dartford Warbler, and Sardinian Warbler. In addition, we recorded the height, cover, and richness of the vegetation in each transect. We analysed the data using canonical correspondence analysis and general linear models. Results The densities of Eurasian Blackcaps and Dartford Warblers varied seasonally. Agricultural land had a significant effect on bird density: positive for the Eurasian Blackcap and negative for the Dartford Warbler. Furthermore, vegetation variables influenced the distribution of the warbler species in different ways. Conclusion Our results suggest that the segregation of the different warbler species across microhabitats can explain their coexistence. Additionally, in contrast to the Dartford Warbler, the Sardinian Warbler showed flexible habitat selection and varied its habitat according to the available niche.

Site-specific and seasonal variation in habitat use of Eurasian otters ( Lutralutra) in western China: implications for conservation.

As a top predator, the Eurasian otter (Lutra lutra) is an indicator of healthy freshwater ecosystems and a flagship species for conservation. Once widespread in China, the species is now distributed mainly in the upper reaches of the great rivers of western China. However, a lack of knowledge on local otter populations continues to hinder their conservation in China. Here, we conducted a detailed study on habitat use of Eurasian otters in Yushu City and Tangjiahe National Nature Reserve in western China using transect surveys. At both study sites, otters preferred to defecate on large rocks close to or protruding from the river and about 50 cm above the waterline. In Yushu, no spraints were found along the 5 km river bank section in the downtown area, with otters preferring sprainting sites with natural banks, riparian zones, and lower human population density. However, this pattern was not obvious at Tangjiahe, where river transformation and human disturbance are minor. Otter river use intensity was negatively correlated with elevation and human population density in Yushu in both seasons. In Tangjiahe, otter river use intensity was positively correlated with prey mass and flow rate and negatively correlated with human population in spring, but positively correlated with human population and negatively correlated with flow rate in autumn. These results reflect the flexible habitat use strategies of otters at different sites, underlining the necessity to study otters living in different regions and habitat types. We provide suggestions for river modification and call for more site-specific studies to promote otter conservation in China.

Flexible habitat use in a migratory songbird expanding across a human-modified landscape: is it adaptive?

Behavioural plasticity during habitat selection plays a key role in determining whether organisms may thrive under human-induced rapid environmental changes. As organisms rely on environmental cues to make decisions, these behavioural responses may be maladaptive. We studied the European stonechat Saxicola torquatus as a model open-habitat bird species breeding in three structurally different land-use types generated by agriculture and forestry activities. In this mosaic landscape, we compared the relative attractiveness and the breeding habitat quality of intensive grassland, Christmas tree plantations and clear-cut patches in plantation forests to test whether habitat selection was adaptive. We examined the settlement pattern of territorial males to evaluate habitat preference. We recorded key parameters reflecting reproductive performances, adult and first-year survival to estimate the individual fitness of the birds and assess the quality of the different land-use types for breeding. Stonechats preferentially settled in clear-cut patches, but their fitness was not found to be markedly different in comparison with the other occupied habitats. Although they produced slightly lower-quality offspring in clear-cut patches, we did not find a negative consequence on first-year survival probabilities or any among-habitat differences in adult survival. With our analysis integrating multiple components of individual fitness, we show that all occupied land-use types are similarly rewarding for the breeding stonechats. Our study shows that some species can benefit from novel land-use types emerging in the landscape as a result of human activities. Flexible habitat selection in the stonechat has most probably contributed to its recent population increase in Western Europe.

Differences in incubation behaviour and niche separation of two competing flycatcher species

Food availability sets the stage for incubation behaviour of a female bird and thereby indirectly determines the nest temperature, which in turn affects development and metabolism of avian embryos. Changes in development and metabolism in turn are known to influence offspring’s ability to adjust to environmental changes later in life. However, few studies have investigated the role of interspecific differences in incubation behaviour in relation to niche separation between competing sibling species. We studied the effects of habitat quality (in terms of caterpillar availability) on incubation behaviour of two ecologically similar and closely related species, collared and pied flycatchers (Ficedula albicollis and F. hypoleuca), in their hybrid zone on the island of Öland, Sweden. Even though both species prefer caterpillar-rich deciduous forests as nesting sites, collared flycatchers, whose nestlings have higher energetic demands, are able to nest only in deciduous forests, whereas pied flycatchers have more flexible habitat requirements. Overall, higher food availability was associated with increased nest attendance, higher incubation temperature and a lower number of foraging trips across species. In addition, collared flycatchers had more frequent and shorter foraging trips across habitat types, allocated more heat to eggs and therefore maintained higher nest temperatures compared to pied flycatchers. We argue that the higher heat allocation or the need to maintain a higher nest temperature for embryo development may constrain collared flycatchers to focus on relatively more profitable prey. Our results highlight the importance of considering incubation behaviour in the context of understanding species differences in niche use.Significance statementNiche separation plays an important role in mitigating effects of competition between closely related species. Whether species differences in incubation behaviour relate to differences in niche use remains unknown. We compared incubation behaviour of two sympatric flycatcher species that differ in sensitivity to food availability. The competitively more dominant and larger species, the collared flycatcher, whose nestlings are more sensitive to food shortages, made more frequent foraging trips but allocated more heat to eggs, leading to higher nest temperature despite lower nest attendance, compared to pied flycatchers. These interspecific differences may be a result of differences in embryo sensitivity or female physiology and contribute to the niche separation between the species, which in turn can facilitate coexistence.

Flexible habitat use and range extension by the striped hog-nosed skunk (Conepatus semistriatus) in Brazil

We present evidence of plasticity in habitat use and range extension of the striped hog-nosed skunk (Conepatus semistriatus) in Brazil. We first compiled literature records of C. semistriatus across its known distribution (N = 390), added new records from primary data (N = 10), and compared the main landscape composition (forest, savannah, grassland, agriculture) among these occurrence sites (N = 400). We unveil that landscape composition among occurrence sites varied widely within and among biomes in Brazil (Caatinga, Cerrado and Atlantic Forest), indicating C. semistriatus presence from dense forested habitats to grasslands and anthropogenic areas (especially agricultural landscapes). Almost 30% of the occurrence records of C. semistriatus are outside of the species known distribution, including records in ecotones between Cerrado-Amazonia biomes, extending its occurrence area in 449,118 km2. We conclude that habitat modification is a driver for the occurrence of C. semistriatus in dense forested habitats, facilitating its distribution expansion to previously unexpected areas.

A resilient system: North American mixed-grass prairie responds rapidly to livestock exclusion

Grasslands are the most threatened terrestrial ecosystem in the world, and as their extent declines so does the abundance of species that depend on them. Periodic resting of rangelands could be used to manipulate plant cover and create wildlife habitat, but its effects may vary with prior grazing intensity. Using a large-scale manipulative grazing experiment conducted from 2006 to 2014 in Grasslands National Park, Canada, we evaluated how the effects of rest on vegetation and songbird abundance varied based on previous cattle stocking rates. Our results indicate that in northern mixed-grass prairies, grazing-induced changes were reversible, even at high stocking rates applied for up to four years. Both vegetation and songbirds were resilient to grazing, generally returning to levels observed prior to livestock reintroduction in three or fewer years following removal of livestock. Songbirds with flexible habitat requirements, such as Passerculus sandwichensis and Ammodramus savannarum, responded more rapidly to livestock exclusion. Recovery of both plant and songbird species occurred more rapidly in lowlands than uplands. The retrogressive nature of succession in North American mixed-grass prairies offers managers an opportunity to take chances when attempting to create wildlife habitat with livestock grazing, as risk of irreversible change is relatively low under moderate climate conditions.

Urban and architectural adaptive strategies for inclusive cities

The current migration flows toward Europe are having a significant impact on social composition, economy, urban services, and on the physical dimensions of cities. Cities have a key role in developing immigration policies and sustainable accommodation models, that can promote an inclusive society as well as local development. Due to the persistence of migratory flows, these models of integration and development cannot be supported by an emergency condition, but they should be based on systematic strategies. This paper presents a series of accommodation models and urban policies, coming from international experimental projects, that we argue can foster integration and urban development. These strategies show the potentials of immigration in boosting urban transformation and regeneration. Innovative strategies for dealing with immigration are based on flexible tools, typically from temporary habitat (housing modules, light construction systems, customized solutions) that find a place inside the city. Integrated design strategies use the existing city as a frame being filled up by flexible houses, through urban densification or regeneration process. Housing dissemination, temporary and flexible architectural solutions and inclusive process are the drivers for developing a flexible habitat, at the base of a more sustainable and democratic city.

Behavior-specific habitat selection by African lions may promote their persistence in a human-dominated landscape.

Co-occurrence with humans presents substantial risks for large carnivores, yet human-dominated landscapes are increasingly crucial to carnivore conservation as human land use continues to encroach on wildlife habitat. Flexibility in large carnivore behavior may be a primary factor mediating coexistence with people, allowing carnivores to calibrate their activity and habitat use to the perceived level of human risk. However, our understanding of how large carnivores adjust the timing and location of behaviors in response to variations in human activity across the landscape remains limited, impacting our ability to identify important habitat for populations outside of protected areas. Here we examine whether African lions (Panthera leo) modify their behavior and habitat use in response to risk of a human encounter, and whether behavior-specific habitat selection allows lions to access feeding opportunities in a human-dominated landscape in Kenya. We determined fine-scale behavioral states for lions using high-resolution GPS and accelerometer data, and then investigated behavior-specific habitat selection at multiple temporal and spatial scales (ranging from 15 minutes to 12 hours and from approximately 200 meters to several kilometers). We found that lions exhibit substantial differences in habitat selection with respect to humans based on behavioral state and time of day. During the day, when risk of human encounter is highest, lions avoided areas of high human use when resting, meandering, and feeding. However, lions specifically selected for habitat near people when feeding at night. Flexible habitat use by lions thus permits access to prey, which appear to concentrate in areas near humans. The importance of habitat near people for feeding was only apparent when analyses explicitly accounted for lion behavioral state and spatiotemporal scale, highlighting the necessity of incorporating such information when investigating human impacts on large carnivore habitat use. Our results support the contention that behavior-specific habitat selection promotes carnivore persistence in human-dominated landscapes, demonstrating the importance of considering not just whether but how large carnivores use habitat near humans when managing vulnerable populations.

Whales in warming water: Assessing breeding habitat diversity and adaptability in Oceania's changing climate.

In the context of a changing climate, understanding the environmental drivers of marine megafauna distribution is important for conservation success. The extent of humpback whale breeding habitats and the impact of temperature variation on their availability are both unknown. We used 19years of dedicated survey data from seven countries and territories of Oceania (1,376 survey days), to investigate humpback whale breeding habitat diversity and adaptability to climate change. At a fine scale (1km resolution), seabed topography was identified as an important influence on humpback whale distribution. The shallowest waters close to shore or in lagoons were favored, although humpback whales also showed flexible habitat use patterns with respect to shallow offshore features such as seamounts. At a coarse scale (1° resolution), humpback whale breeding habitats in Oceania spanned a thermal range of 22.3-27.8°C in August, with interannual variation up to 2.0°C. Within this range, both fine and coarse scale analyses of humpback whale distribution suggested local responses to temperature. Notably, the most detailed dataset was available from New Caledonia (774 survey days, 1996-2017), where encounter rates showed a negative relationship to sea surface temperature, but were not related to the El Niño Southern Oscillation or the Antarctic Oscillation from previous summer, a proxy for feeding conditions that may impact breeding patterns. Many breeding sites that are currently occupied are predicted to become unsuitably warm for this species (>28°C) by the end of the 21st century. Based on modeled ecological relationships, there are suitable habitats for relocation in archipelagos and seamounts of southern Oceania. Although distribution shifts might be restrained by philopatry, the apparent plasticity of humpback whale habitat use patterns and the extent of suitable habitats support an adaptive capacity to ocean warming in Oceania breeding grounds.