Context. Drones can be used as frightening devices to resolve avian-agriculture conflicts. Blackbird (Icteridae) flocks respond to drones making them a suitable scare device to protect sunflower (Helianthus annuus), but with limited efficacy on large flocks. Integrating a non-lethal avian repellent on the same drone as used for hazing may increase efficacy, but responses of flocks towards drones with spraying capabilities need to be evaluated to inform application protocols.

Aim. We evaluated flock responses to a drone capable of spraying when first approached and with 10 min of hazing, to inform protocols for delivering repellents on agricultural landscapes.

Methods. We used eye-in-the-sky drones to video the drone with spraying capabilities and observed whether flocks took flight within 80 m (i.e. range of potential spray drift). We measured flight initiation distance (FID) when close approach occurred (i.e. drone ≤80 m from flock). While hazing, we piloted the drone to (1) repeatedly cut through a flock and create chaos or (2) move along the flock edge to herd birds out of target habitat (i.e. sunflower or cattail). We recorded abandonment, flock reduction, and return rate of birds in response to drone hazing.

Key results. The probability of a close approach was greater with birds in cattail than in sunflower, but habitat did not influence mean FID when the drone was within 80 m (FID = 40 m ± 14.3 s.d.), abandonment (31 of 60 flocks), or mean percentage flock reduction (50% ± 37 s.d.). FID was shorter with smaller flocks, later in the day, but abandonment increased with smaller flocks as the day progressed. Although 52% of flocks abandoned, 81% returned after the end of hazing. Flight path of the drone (i.e. chaotic or herding) did not affect abandonment or flock reduction.

Conclusions. Although blackbirds perceived the drone approach as riskier (>FID) while foraging in sunflower earlier in the day, increased abandonment that occurred later in the day was likely to be due to satiation and movement to night-time roosts, instead of hazing impacts. Birds in sunflower interspersed with cattail used local refugia until the threat passed, then resumed foraging.

Implications. If applying an avian repellent with a spraying drone, protocols should consider time of day, flock size, and habitat. When selecting a flight path, pilots need to be concerned only with optimizing spray drift to reach areas with foraging blackbirds.

Context. The gharial is a critically endangered freshwater riverine crocodilian found in few Indo-Gangetic rivers and the Mahanadi River. With very few individuals remaining, the species in the Mahanadi River is on the verge of extirpation and requires conservation attention for their continuous existence. Although essential ecological information is available here to an extent, the human dimensions of gharial conservation is overlooked.

Aim. Therefore, we aimed to examine the dependencies of local people on the Mahanadi River and their perceptions of gharial conservation.

Methods. Opportunistic method was used to select respondents, and an open and close-ended questionnaire was used for survey. Descriptive statistics and logistic regressions were used for data analysis.

Key results. The Mahanadi River played crucial role in respondents’ lives who depend on the river in both tangible and intangible ways such as earning their livelihoods and performing everyday sanitation and minerals extraction. Initially, most of the respondents perceived gharials negatively, which could be attributed to their lack of awareness about gharial ecology and behaviour. However, age, awareness and incentives provided for gharial conservation influenced respondents to positively perceive gharial conservation in the Mahanadi River.

Conclusion. The study observed how lack of awareness negatively affects gharial conservation effort in the Mahanadi River as people perceive threat from gharials as similar to mugger and saltwater crocodiles, both of which are much more dangerous to humans than gharials.

Implications. The finding can be taken into consideration to promote awareness about gharial ecology and behaviour among the locals with warning information on muggers and saltwater crocodiles in the Mahanadi River. That may be useful for gharial conservation.

Aging is a ubiquitous component of the life history and biological function of all species. In wildlife studies, estimates of age are critical in order to understand how a species’ ecology, biology and behaviour vary in parallel with its life-history events. Longitudinal studies that track individuals as they age are limited in fruit bats, as recapture is difficult for vagile species with nomadic lifestyles. Most studies estimate age by the broad categorisation of individuals with similar biological characteristics or morphometrics into age classes (e.g. sub-adult and adult). In this review, we systematically compile and compare the age classifications used across a range of studies on Australian flying-foxes (Pteropus). We discuss the associated challenges of those classifications and identify current knowledge gaps. The terminology, methodology and explanations behind age classifications were inconsistent across reviewed studies, demonstrating that age classifications are highly subjective – particularly when identifying reproductively immature individuals. Downstream analyses and cross-disciplinary data use are likely to be compromised as a result. Further known-aged studies of flying-foxes would assist in clarifying variations of key parameters among non-adult individuals. We also encourage greater consistency in age classification and reporting, ensuring that classifications are well defined and biologically sound.

Context. Accurate and precise estimates of wildlife abundance and distribution are critical for robust ecological inference and effective management. However, obtaining this information for mesocarnivores is challenging because they are elusive and highly mobile.

Aims. To compare four common population metrics (occupancy, local abundance, relative abundance, and density) for monitoring unmarked populations and the influence of three habitat covariates on these population metrics.

Methods. For five mesocarnivores species we used data collected at 74 camera traps deployed in the northeastern USA in summer 2021 to fit (1) models that estimated probabilistic occupancy, (2) Royle–Nichols models that estimated local abundance, (3) Poisson distributed general linear models that estimated relative abundance, and (4) random encounter and staying time (REST) models that estimated density. We also quantified habitat relationships across these four different models and compared the resultant inferences.

Key results. Density and relative abundance had the highest correlation (Pearson correlation (r) = 0.91), whereas occupancy and density had the lowest correlation (r = 0.19). Density estimates for all species were consistent with expectations and similar to those reported in previous studies. The effects of habitat covariates changed across metrics, such that a significant effect of a covariate on one metric was not indicative of a significant influence on the other metrics. There were only two instances of a significant effect of a covariate on all metrics, and two instances where the influence of a covariate had opposite, albeit insignificant, effects on two metrics.

Conclusions. Estimates of occupancy and local abundance for mesocarnivores derived from camera traps may not be reliable proxies for density. However, relative abundance, as derived from detection rates, could be a promising means of monitoring density with less intensive data processing. Mesocarnivore habitat relationships changed across these metrics.

Implications. When designing monitoring or research programs, practitioners should be cautious about assuming that inferences derived from camera trap estimates of these four population metrics are interchangeable. Further, we highlight how the REST model offers a promising new means for monitoring multiple mesocarnivores simultaneously, and likely other unmarked species, via density estimates.

Context. Our understanding of population- and ecosystem-level processes commonly considers conspecific individuals to be ecologically equivalent. However, individuals of the same species may use resources differently, supporting the prevalence of individual specialisation or ‘apparent specialisation’. Individuals within a geographically defined population may also exhibit complex subpopulation movements, whereby individuals show philopatry to specific regions that further drives individual variation.

Aims. White sharks (Carcharodon carcharias) are top predators in temperate to tropical ecosystems. In Australia, two discrete subpopulations of white sharks (an east and a southwest subpopulation) have been proposed based on genetics and limited movement across Bass Strait. We aimed to characterise the extent of ontogenetic divergence in resource–habitat behaviour of white sharks from both regions.

Methods. We used high-resolution retrospective stable isotope profiles (δ¹⁵N and δ¹³C) of 74 white shark vertebral centra to examine ontogenetic trophic–habitat signatures for individuals sampled from both regions.

Key results. Our results demonstrate isotopic separation between juvenile–subadult sharks sampled east (−13.7 ± 0.72 δ¹³C; 14.2 ± 0.8 δ¹⁵N, n = 47) and southwest (−14.4 ± 0.6 δ¹³C; 12.5 ± 1.2 δ¹⁵N, n = 27) of Bass Strait, but with strong oscillatory trends across both regions, likely related to seasonal movements. Relative individual niche width revealed apparent specialised behaviour of juvenile–subadult sharks within both regions.

Conclusions. Retrospective ontogenetic isotopic profiles of vertebrae from Australian white sharks provide evidence to support an ecological two-population model for juvenile and subadult life stages.

Implications. Given many marine top predators are undergoing systematic population declines, understanding individual variation in diet and movement in the context of population structure and true or apparent specialisation is central to elucidating their ecological roles.