Habitat Resources Research Articles

Red snapper excavate sediments around artificial reefs: observations of ecosystem-engineering behavior by a widely distributed lutjanid

Hard substrate and vertical relief are limited habitat resources for reef-associated species in many regions. On the West Florida Shelf (WFS) of the Gulf of Mexico, red grouper Epinephelus morio act as ecosystem engineers by excavating sediments to expose limestone bedrock. Excavations can exceed 25 m in diameter and 2 m in depth and are among the most abundant WFS seafloor features at depths between 40 and 110 m. As part of a survey of hard-bottom habitats and associated reef fish assemblages, 1203 excavations were identified in WFS waters along the Florida Panhandle between 2014 and 2019. These excavations often contained subsided artificial reef material within their interior and infrequently included E. morio among observed fishes. We video-identified red snapper Lutjanus campechanus excavating sediments around 2 subsided artificial reefs in 2015 and 2017 for a total of approximately 56 min of excavation activity. A total of 24 excavation events were documented around a tire pile in 2015, and 5 were documented around a pyramid-shaped reef module in 2017. These observations help to explain the subsidence of artificial reefs and apparent excavation around their bases despite the scarcity of previously known excavating species. This suggests that L. campechanus might be ecosystem engineers on the WFS.

How an unprecedented wildfire shaped tree hollow occurrence and abundance—implications for arboreal fauna

BackgroundTree hollows are an important habitat resource used by arboreal fauna for nesting and denning. Hollows form when trees mature and are exposed to decay and physical damage. In the absence of excavating fauna, hollow formation can take up to 200 years in Australian temperate Eucalyptus forests, making tree hollows a critical but slow forming habitat feature. The increasing frequency and severity of wildfires due to climate change has led to increased concern about the landscape-scale loss of nesting space for arboreal fauna, including endangered species such as the folivorous southern greater glider (Petauroides volans). To understand patterns of nesting resource availability, we assessed drivers of hollow occurrence in southeastern Australian mixed-species Eucalyptus forests and quantified the effects of an unprecedented large-scale wildfire, the 2019/2020 Black Summer bushfires, on hollow occurrence and abundance.ResultsTree size and shape, as well as site productivity and topography, were important predictors for hollow occurrence both before and after the fires. The occurrence of the southern greater glider was strongly dependent on high proportions of hollow-bearing trees. While high fire severities had a negative impact on southern greater glider occurrence, the number of hollow-dependent arboreal species was not affected. While the wildfires significantly reduced hollow abundance, we did not find significant effects on hollow occurrence. Fires altered the relationship between tree size and hollow occurrence expressed as a change in the probability of hollow occurrence, with a higher likelihood at smaller tree sizes after the fires.ConclusionsOur findings suggest that post-fire nesting space may be reduced at the tree-scale, while at the stand-scale, hollow-bearing trees persist as biological legacies. These persisting trees can support the recovery of hollow-dependent arboreal fauna, such as the endangered southern greater glider by providing denning and nesting space. Hollow-bearing trees that survived the fires have the potential to form new hollows faster compared to undisturbed mature trees.

The Occurrence of the American Burying Beetle (Nicrophorus americanus) and Associated Silphid Beetle Community in South Dakota: Implications for Managed Relocation

The American burying beetle, Nicrophorus americanus Olivier (Coleoptera: Siliphidae), is a federally threatened species in the United States, occurring in less than 10% of its historic range. The continued monitoring of extant populations found in South Dakota, the northernmost edge of its confirmed range, is imperative to future conservation efforts, especially with the predicted loss of the species in southern regions because of climate change. Proposed strategies to preserve the species include the reintroduction or translocation of individuals from habitats that have become unsuitable. Beyond adequate habitat and carrion resource requirements, community-level silphid interactions may challenge these efforts because of competition. From 2018 to 2020, we used 80 carrion-baited pitfall traps per year to conduct two 5-day surveys in June and August. A total of 25,923 Silphidae belonging to 15 species were collected in 1200 trap nights. Cumulatively, 1150 N. americanus were captured and marked with 263 recaptures. Like past findings, N. americanus was concentrated in western Tripp County with limited occurrence in Gregory and Todd Counties, suggesting no expansion of their known range in the past decade. Generalized linear mixed-effects models indicated N. americanus abundance was significantly predicted by the co-occurrence of the carrion beetles Oieceoptoma inaequale F. and Oiceoptoma noveboracense Forster, whereas pitfall trap catches dominated by the burying beetle Nicrophorus marginatus F. had predictively less N. americanus. Collectively, these data provide insights into the existing, northernmost N. americanus population dynamics and silphid beetle communities. Concurrent with monitoring extant populations, the characterization of silphid communities that co-occur with N. americanus may provide much-needed information for managed relocation opportunities.

Unveiling activity patterns of the deer Odocoileus virginianus (Artiodactyla: Cervidae) and its predators in Mexico's Arid Region

Introduction: Size, predator presence, and habitat nutritional quality influence herbivorous species' activity patterns and resource utilization. Objectives: This study aims to determine the relative abundance and activity patterns of white-tailed deer (Odocoileus virginianus) and their main predators. Methods: The study was conducted in the WMU "Bienes Comunales Santa Cruz Nuevo" in Totoltepec de Guerrero, Puebla, Mexico. Twenty-two quadrants were randomly selected, and camera traps were installed. Over a two-year period (2018-2020), wildlife visits were recorded to estimate the relative abundance index (RAI), activity patterns, and overlap coefficient (Dhat1) of white-tailed deer and their predators based on their activity schedule. Results: The estimated RAI for deer was 7.2%, while it was 3.4% for coyotes (Canis latrans), 2.3% for bobcats (Lynx rufus), and 0.14% for pumas (Puma concolor). White-tailed deer were observed in 31% of the camera traps, while coyotes were captured in 68% of them. The overlap of the activity schedule, Dhat1, between deer and coyotes was 0.18. In contrast, the activity overlap between foxes and deer was higher (Dhat1: 0.2979; EE 0.037) based on the analysis of variance. The activity pattern of coyotes indicated they were crepuscular, with increased activity during the afternoon and night. However, an increase in activity synchronized with deer's patterns was also observed. The bobcat coincided with deer in 10% of the cameras, but due to the limited number of observations, it was not possible to estimate the activity overlap between these species. Conclusions: The activity overlap between white-tailed deer and foxes is more significant than that of deer and coyotes in this region. The activity overlap between deer and coyotes is lower compared to other parts of the world.

Predation event and shelter site use by a threatened monitor lizard, Varanus rosenbergi, in the Little Desert, Victoria

AbstractHeath monitors (Varanus rosenbergi) are arguably the most thoroughly studied Australian varanid, largely stemming from long‐term research on Kangaroo Island, South Australia. However, research on other populations within this species' disjunct distribution is limited. We opportunistically tracked a heath monitor in the Little Desert National Park, Victoria, after it consumed a painted dragon (Ctenophorus pictus) which we were radiotracking for another study. We report the first record of a heath monitor depredating a painted dragon, as well as the first record of heath monitors repeatedly using a hollow log for shelter. The hollow log was occupied on 10 consecutive occasions over 18 days, and then again on five occasions 9–11 months later. Our observations identify hollow logs as a habitat resource which should be considered in conservation strategies for this threatened monitor lizard. Furthermore, we observed two individuals in close proximity, possibly a breeding pair, in January. This implies that breeding may occur in summer for the Victorian mallee population, as has been reported in other populations, rather than in spring as has been speculated. Research is sorely needed across this species' disjunct distribution across southern Australia. To date, populations of heath monitors in the Victorian mallee have garnered no scientific study, despite their listing as Critically Endangered.

Widespread habitat loss leads to ecosystem-scale decrease in trophic function.

Natural and anthropogenic disturbances have led to rapid declines in the amount and quality of available habitat in many ecosystems. Many studies have focused on how habitat loss has affected the composition and configuration of habitats, but there have been fewer studies that investigate how this loss affects ecosystem function. We investigated how a large-scale seagrass die-off altered the distribution of energetic resources of three seagrass-associated consumers with varied resource use patterns. Using long-term benthic habitat monitoring data and resource use data from Bayesian stable isotope mixing models, we generated energetic resource landscapes (E-scapes) annually between 2007 and 2019. E-scapes link the resources being used by a consumer to the habitats that produce those resources to calculate a habitat resource index as a measurement of energetic quality of the landscape. Overall, our results revealed that following the die-off there was a reduction in trophic function across all species in areas affected by the die-off event, but the response was species-specific and dependent on resource use and recovery patterns. This study highlights how habitat loss can lead to changes in ecosystem function. Incorporating changes in ecosystem function into models of habitat loss could improve understanding of how species will respond to future change.

The behavioural costs of overcrowding for gregarious cave-dwelling bats.

Bats are known for their gregarious social behaviour, often congregating in caves and underground habitats, where they play a pivotal role in providing various ecosystem services. Studying bat behaviour remains an underexplored aspect of bat ecology and conservation despite its ecological importance. We explored the costs and impacts of overcrowding on bat social behaviour. This study examined variations in bat behavioural patterns between two distinct groups, aggregated and non-aggregated male Rousettus amplexicaudatus, within the Monfort Bat Cave Sanctuary on Mindanao Island, Philippines. We found significant variations in the incident frequencies of various bat behavioural activities, particularly aggression and movement, between these two groups. The increase in aggregation was closely related to negative social behaviour among bats. In contrast, sexual behaviour was significantly related to the positive behaviour of individual bats and was headed in less crowded areas. The disparities in bat behaviour with an apparent decline in bat social behaviour because of overcrowding, with more aggressive behaviours emerging, align with the 'behavioural sink' hypothesis. Our study underscores the importance of considering habitat quality and resource availability in the management and conservation of bat colonies, as these factors can reduce the occurrence of aggressive and negative social behaviours in colonies with high population density by providing alternative habitats.

Ammonification by kelp associated microbes increases ammonium availability.

Microbes contribute biologically available nitrogen to the ocean by fixing nitrogen gas from the atmosphere and by mineralizing organic nitrogen into bioavailable dissolved inorganic nitrogen (DIN). Although the large concentration of plants and algae in marine coastal environments provides ample habitat and reliable resources for microbial communities, the role of the microbiome in host-microbe nitrogen cycling remains poorly understood. We tested whether ammonification by epiphytic microbes increased water column ammonium and improved host access to nitrogen resources by converting organic nitrogen into inorganic nitrogen that is available for assimilation by hosts. When bull kelp (Nereocystis luetkeana) in the northeast Pacific was incubated with 15N labelled amino acid tracers, there was accumulation of 15N in kelp tissue, as well as accumulation of 15NH4 in seawater, all consistent with the conversion of dissolved organic nitrogen to ammonium. Metagenomic analysis of surface microbes from two populations of Nereocystis indicated relative similarity in the percentage of genes related to ammonification between the two locations, though the stressed kelp population that had lower tissue nitrogen and a sparser microbiome had greater ammonification rates. Microbial communities on coastal macrophytes may contribute to the nitrogen requirements of their hosts through metabolisms that make ammonium available.

Functional diversity and secondary production of macrofaunal assemblages can provide insights of biodiversity-ecosystem function relationships

BackgroundSemi-enclosed bays are important links in the material cycle and energy flow between terrestrial and marine ecosystems. They are also areas of intense human activities and heavily influenced by such activities as aquaculture, industrial and agricultural wastewater discharge. The rate of biodiversity loss and changes in ecosystems have prompted research into the relationship between species diversity and ecosystem functioning. Studies have shown that application of functional diversity indices is useful for assessing the status of ecosystem functioning. We quantitatively sampled macrofauna in a semi-enclosed bay in four seasons and analyzed the relationship between species, functional diversity and secondary production, biomass and feeding functional groups of macrofauna.ResultsThe annual secondary production was 325.01 kJ m−2 year−1. Detritivorous, carnivorous and planktophagous feeders were the main functional groups of macrofauna. Differences in the spatial–temporal distribution of functional groups were influenced by Ruditapes philippinarum and Hemileucon bidentatus. Functional richness had significant negative correlations with macrofaunal biomass and secondary production. Functional divergence, functional dispersion and Rao's quadratic entropy had highly significant negative correlations with macrofaunal biomass and secondary production.ConclusionThe results showed that high overlap of ecological niches can increase competition for habitat resources, leading to a decline in biomass and secondary production. In addition, aquaculture could promote the use of habitat resources to some extent, while it could increase competition for ecosystem resources (including habitat resources, atmospheric resources, water resources, etc.). Functional diversity is a good indicator for the ecosystem functioning and the competition status for habitat resources, which can provide insights into the current state of ecosystem function.

Use of wildlife-friendly structures in residential gardens by animal wildlife: evidence from citizen scientists in a global biodiversity hotspot

Private gardens comprise a large component of greenspace in cities and can offer substantial conservation opportunities. There has been strong advocacy from researchers, policymakers, and conservation practitioners to engage householders in wildlife-friendly gardening practices to increase the quantity, quality and connection of habitat resources for urban wildlife. Despite this call to action, there remains limited knowledge on the use and benefit of some wildlife-friendly structures within gardens, such as artificial refuges and water sources. In collaboration with 131 citizen scientists in southwestern Australia, we examined the use of seven wildlife-friendly structure types by four vertebrate taxa groups. Following 2841 wildlife surveys undertaken between 31 July 2022 and 22 February 2023, we found that all structures were used primarily by target taxa, water sources were often used by relatively common species, certain structures such as possum shelters were used by rare and threatened species (e.g. western ringtail possum), and that there was evidence of animals making use of the wildlife-friendly structures for reproduction (e.g. bird eggs in nest boxes and tadpoles in water sources). Water sources were used more frequently and by a greater diversity of wildlife than artificial refuges. In particular, bird baths were used by the highest number of species (mainly birds) while ponds were used by the greatest variety of taxa (birds, reptiles, frogs, mammals). Our findings provide evidence-based support for the advocacy of wildlife-friendly gardening practices and further highlight the role of residential gardens for biodiversity conservation.

Reviewing the role of AI in environmental monitoring and conservation: A data-driven revolution for our planet

The rapid increase in human activities is causing significant damage to our planet's ecosystems, necessitating innovative solutions to preserve biodiversity and counteract ecological threats. Artificial Intelligence (AI) has emerged as a transformative force, providing unparalleled capabilities for environmental monitoring and conservation. This research paper explores the applications of AI in ecosystem management, including wildlife tracking, habitat assessment, biodiversity analysis, and natural disaster prediction. AI's role in environmental monitoring and conservation includes wildlife tracking, habitat assessment, resource conservation, biodiversity analysis, and species identification. AI algorithms analyze camera trap footage, drone imagery, and GPS data to identify and estimate population sizes, leading to improved anti-poaching efforts and enhanced protection of diverse species. Habitat assessment and resource conservation involve AI-powered image analysis, which aids in assessing forest health, detecting deforestation, and identifying areas in need of restoration. Biodiversity analysis and species identification are achieved through AI algorithms that analyze acoustic recordings, environmental DNA (eDNA), and camera trap footage. These innovations identify different species, assess biodiversity levels, and even discover new or endangered species. AI-powered flood prediction systems provide early warnings, empowering communities with better preparedness and evacuation efforts. Challenges, such as data quality and availability, algorithmic bias, and infrastructure limitations, are acknowledged as opportunities for growth and improvement. In policy and regulation, the paper advocates for clear frameworks prioritizing data privacy and security, algorithmic transparency, and equitable access. Responsible development and ethical use of AI are emphasized as foundational pillars, ensuring that the integration of AI into environmental conservation aligns with principles of fairness, transparency, and societal benefit.

Functional ecological traits in young and adult thalli of canopy-forming brown macroalga Gongolaria barbata (Phaeophyta) from a transitional water system.

Gongolaria barbata is a canopy-forming brown macroalga that thrives in the intertidal and subtidal habitats of the warm-temperate Mediterranean Sea, which is particularly exposed to environmental changes due to its peculiar geographical location and exposure to both global and local stressors. Testing whether this species is featured by specific functional, eco-physiological and biochemical traits allowing an efficient use of habitat resources and adaptation to environmental stress, and whether this potential might change with population growth, is essential for predicting the performance of the algae under different environmental abiotic variables (e.g., temperature, nutrient availability, light) and biotic interactions (such as grazing). Young (juveniles) and adult thalli of G. barbata were sampled in the winter season from the Venice Lagoon, Italy, featured by high environmental changes (temperature, salinity) and analyzed for thallus dry matter content (TDMC), photosynthetic activity, photosynthetic pigment and protein content, and antioxidant capacity to assess if thallus age may be considered a significant driver in determining the ecological responses of this species to environmental changes. Our results showed that TDMC was higher in adults than juveniles. At the functional level, rapid light curves indicated an elevated photosynthetic efficiency in juveniles compared to adults highlighted by the higher quantum yield of PSII electron transport, electron transport rate, and Rubisco content observed in juveniles. On the contrary, adults exhibited a higher non-photochemical quenching and total pigment concentration. No difference in maximum PSII photochemical efficiency and D1 protein content between the two thalli groups was found. Along with better photosynthesis, juveniles also displayed a higher amount of total polyphenols, flavonoids, and tannins, and a stronger antioxidant capacity compared to adults. Our findings revealed significant differences in the eco-physiological characteristics of G. barbata at different growth stages. It was observed that young thalli, allocate more energy to photosynthesis and chemical defenses by increasing the production of antioxidant compounds, such as polyphenols, flavonoids, and tannins. With growth, thalli likely adopt a more conservative strategy, reducing photosynthesis and promoting structural biomass accumulation to mitigate the potential risks associated with prolonged exposure to environmental stressors, such as the wavy way. Although our study focused on a single phase of G. barbata life cycle under winter settings, it offers preliminary insights into this species eco-physiological traits and auto-ecology. Future research could explore the potential implications of these findings, evaluating the species' resilience to environmental changes at the population level.

AGGRESSIVE BEHAVIOR OF Rheohyla miotympanum (ANURA: HYLIDAE) IN NORTHERN HIDALGO, MEXICO

Anurans communicate primarily through calls, which can be classified into three categories (reproductive, defensive and aggressive) according to the social context in which they occur. Aggressive calls are usually emitted by males to defend habitat resources (calling sites, females), generally accompanied by physical aggression. Here, we report aggressive behavior between two Rheohyla miotympanum males, possibly triggered by defense of the calling site and for the opportunity for amplexus (receptive female, approximately 80 cm from the scene). This behavior was characterized by physical contact (fight) and the emission of aggressive calls between both males. Future studies are required that make specific observations of the calls, considering the proximity and density of conspecifics, which could help to understanding the main causes of the aggressive behavior of this and other anuran species.

Not all sanctuaries are created equal: variation in protected area selection by wintering mallards

AbstractPublic lands managed for wildlife frequently provide various forms of sanctuary to increase residency times and allow access to energetic and other habitat resources for waterfowl. The influence of sanctuary type and disturbance regime on resource use and fine‐scale movements of waterfowl has not been investigated extensively using currently available transmitter technologies. We examined mallard (Anas platyrhynchos) use of various types of waterfowl sanctuary and non‐sanctuary areas in the Mississippi Alluvial Valley region of eastern Arkansas, USA, during winters of 2019–2021. We deployed 105 global positioning system transmitters on mallards at 4 closed‐access spatial sanctuaries on or adjacent to Dale Bumpers White River National Wildlife Refuge. We used hourly transmitter locations to examine mallard use of public sanctuary areas, public hunt areas, and private lands using integrated step selection analysis. Public sanctuary areas provided varying levels of protected status, public hunt areas allowed for varying levels of hunting intensity by duck hunters, and private lands were open to waterfowl hunting and other forms of private uses but may or may not have been hunted at any specific frequency. Mallards selected spatial sanctuary and avoided public hunt areas, other sanctuary types, and private lands during the day. In contrast, mallards selected for private lands over spatial sanctuary at night. Mallards tended to avoid areas that allowed duck hunting or used them during the night when risk of harvest mortality was removed. After the hunting season closed, mallards began using areas that previously allowed duck hunting during the day, suggesting that risk was the primary factor influencing site use. Moreover, mallards were 1.6 times more likely to use public daily hunt areas and 2.1 times more likely to use private lands potentially open to hunting during the day than spatial sanctuary 2 weeks after the close of duck hunting season in February. Spatial sanctuaries appear more effective in influencing mallard use than temporal sanctuaries or inviolate sanctuaries, which are commonly used by state and federal agencies. Partial daily, daily, or activity‐specific (e.g., no hunting past noon, no hunting 3 days/week, no waterfowl hunting) closures to encourage mallard use of temporal sanctuaries do not appear to reduce the perceived harvest‐related risk to mallards enough for them to view these areas as accessible or significantly increase their use.

Response of pollinator taxa to fire is consistent with historic fire regimes in the Sierra Nevada and mediated through floral richness†.

Many fire-prone forests are experiencing wildfires that burn outside the historical range of variation in extent and severity. These fires impact pollinators and the ecosystem services they provide, but how the effects of fire are mediated by burn severity in different habitats is not well understood. We used generalized linear mixed models in a Bayesian framework to model the abundance of pollinators as a function of burn severity, habitat, and floral resources in post-fire, mid-elevation, conifer forest, and meadow in the Sierra Nevada, California. Although most species-level effects were not significant, we found highly consistent negative impacts of burn severity in meadows where pollinators were most abundant, with only hummingbirds and some butterfly families responding positively to burn severity in meadows. Moderate-severity fire tended to increase the abundance of most pollinator taxa in upland forest habitat, indicating that even in large fires that burn primarily at high- and moderate-severity patches may be associated with improved habitat conditions for pollinator species in upland forest. Nearly all pollinator taxa responded positively to floral richness but not necessarily to floral abundance. Given that much of the Sierra Nevada is predicted to burn at high severity, limiting high-severity effects in meadow and upland habitats may help conserve pollinator communities whereas low- to moderate-severity fire may be needed in both systems.

Selection of summer feeding sites and food resources by female migratory caribou (Rangifer tarandus) determined using camera collars.

Migratory caribou (Rangifer tarandus) is a socioeconomically and culturally key species for northern communities in the Arctic, and most of its populations are experiencing a sharp decline. Female migratory caribou depend on the availability of summer habitat resources to meet the needs associated with lactation and the accumulation of fat reserves to survive when resources are less abundant. Because of the large scales at which habitat and resource data are usually available, information on how female migratory caribou select habitat and resources at fine scales in the wild is lacking. To document selection of summer feeding sites, we equipped 60 female caribou with camera collars from 2016 to 2018. We collected a total of 65,150 10-sec videos between June 1st and September 1st for three years with contrasted spring phenology. We determined the selection at the feeding site scale (3rd scale of Johnson) and food item scale (4th scale of Johnson) using resource selection probability functions. Wetlands were highly selected as feeding sites in June and July while they were avoided in August. Shrublands were mostly selected in July and August. At the resources scale, lichen, birch, willow, and mushrooms were the most strongly selected resources. Our results provide precise and novel information on habitat selection at feeding sites and food resources selected by female caribou in the wild. This information will help understand foraging patterns and habitat selection behavior of female migratory caribou and will contribute to the management and conservation of its declining populations.

Usefulness of Living Mulch in Rows in a Dwarf Pear, Pyrus communis L., Orchard

The key problem in the cultivation of densely planted dwarf orchards is the removal of weeds—trees’ competitors for habitat resources. There is an urgent need to look for ecological methods of weed control as an alternative to herbicides that are harmful to the environment. The use of living mulch (LM) in tree rows additionally improves soil quality but usually weakens tree growth and may reduce yield. The aim of this 11-year experiment was to assess the impact of the use of two different LMs in rows (Trifolium repens—Tr and Agrostis capillaris—Ac) on the growth, yield, and fruit quality of three pear cultivars on Quince S1 rootstock compared to herbicide fallow. The presence of LM did not significantly affect tree growth. There was no significant effect of either mulch on the cumulative yield. However, for the first 4–6 years, the yield was clearly lower than in the control, which changed in the later years of the experiment. When LMs were used, pear trees showed a significantly lower tendency to alternate fruiting. The average fruit weight was significantly lower in Tr, but the other parameters of external fruit quality did not differ significantly. Furthermore, a smaller share of ultra-small fruit was found with LM compared to the control. The LM did not significantly affect such parameters as the content of soluble solids, vitamin C, Ca, Mg, and P. The use of Ac in dwarf pear orchards with sowing in tree rows is recommended in the 2nd or 3rd year after planting at the earliest.

Trout bioenergetics as a process‐based tool to estimate ecological risk in a regulated river

AbstractBioenergetics models produce quantitative flow‐ecology relationships that summarize changes in habitat and food resources from altered flows. We used a drift‐foraging bioenergetics model to quantify the net rate of energetic intake (NREI) for trout above and below a water diversion. NREI is reduced by >95% below the water diversion in July–September, when up to 98% of unimpaired flows are diverted. We then used a risk‐based approach to estimate the maximum diversion rate, expressed as a percentage of unimpaired flow, that would produce NREI values that are not significantly lower than values under unimpaired flows throughout a 62‐year period. NREI decreased with increased precent‐of‐flow diversion rates in low‐flow months (July–September). Diversion rates of 16% in July and 9% in August and September would maintain NREI within the range of unimpaired flow conditions. In higher flow months, May–June, increasing diversions brought estimated instream flows closer to the peak NREI flow, leading to the assessment that increased diversions would increase NREI. Bioenergetic models can be used to develop protective flow rates at times of the year when fish growth and production would be high under unimpaired flows, which often coincides with when water is diverted. Our study is the first to develop protective percent‐of‐flow diversion rates for holistic flow management using a quantitative process‐based and fish‐centric ecological metric.

Anthropogenic nesting sites and density of Burrowing Parrot (Cyanoliseus patagonus) in northern Argentinian Patagonia

BackgroundThe expansion of human activities and the development of urban centers are among the main driving forces accounting for the transformation and loss of natural environments. At the same time, and especially for some birds, anthropogenic activity provides new habitat resources. This is the case of the Burrowing Parrot (Cyanoliseus patagonus), in and around Bahía Blanca, a city of ca. 335,000 inhabitants in northern Argentinian Patagonia, where urban and rural quarries and constructed ravines on roadsides are where most of its reproductive activity occurs.MethodsIn this study we monitored anthropogenic nesting sites and estimated the number of breeding pairs from 2018 to 2023 through censuses conducted annually in 23 colonies within a radius of up to 20 km from the communal roost located in the city.ResultsMost of the nesting sites (57%), and the breeding pairs (60 to 80%) were in urban environments, and the remaining in rural areas. Ravines along roadsides and quarries represented the substrate that was most frequently used for nesting. Mean nest density was significantly higher in roadside ravines compared to quarries, and, in turn, higher in urban roadsides compared to rural roadsides.ConclusionAnthropogenic substrates appear as key components for the reproduction of the species, with possible effects on its numbers. The ability of the Burrowing Parrot to reproduce on artificial substrates in the urban environment, and especially the rapid colonization of recently opened sites, represents a new perspective for the conservation and management of its populations.

Isotopic niche overlap among foraging marine turtle species in the Gulf of Mexico.

Sympatric species may overlap in their use of habitat and dietary resources, which can increase competition. Comparing the ecological niches and quantifying the degree of niche overlap among these species can provide insights into the extent of resource overlap. This information can be used to guide multispecies management approaches tailored to protect priority habitats that offer the most resources for multiple species. Stable isotope analysis is a valuable tool used to investigate spatial and trophic niches, though few studies have employed this method for comparisons among sympatric marine turtle species. For this study, stable carbon, nitrogen, and sulfur isotope values from epidermis tissue were used to quantify isotopic overlap and compare isotopic niche size in loggerhead (Caretta caretta), green (Chelonia mydas), and Kemp's ridley (Lepidochelys kempii) turtles sampled from a shared foraging area located offshore of Crystal River, Florida, USA. Overall, the results revealed high degrees of isotopic overlap (>68%) among species, particularly between loggerhead and Kemp's ridley turtles (85 to 91%), which indicates there may be interspecific competition for resources. Samples from green turtles had the widest range of isotopic values, indicating they exhibit higher variability in diet and habitat type. Samples from loggerhead turtles had the most enriched mean δ34S, suggesting they may forage in slightly different micro-environments compared with the other species. Finally, samples from Kemp's ridley turtles exhibited the smallest niche size, which is indicative of a narrower use of resources. This is one of the first studies to investigate resource use in a multispecies foraging aggregation of marine turtles using three isotopic tracers. These findings provide a foundation for future research into the foraging ecology of sympatric marine turtle species and can be used to inform effective multispecies management efforts.