Monitoring long-tailed bat (Chalinolobus tuberculatus) activity and investigating the effect of aircraft noise on bat behaviour in a modified ecosystem

Echolocating bats are one of the most diverse and cryptic mammalian groups. Individuals are typically small, nocturnal, highly mobile, and rely on high frequency (greater than 20 kHz) vocalisations (i.e. echolocation pulses and social calls) inaudible to humans. It is estimated that a quarter of the more than 1,200 recognized bat species are threatened, which has largely been attributed to habitat loss through anthropogenic activities. Therefore, a need exists to improve our understanding of bat behaviour, habitat use and how anthropogenic activities might impact bats, especially in modified habitats. A primary aim of New Zealand’s Bat Recovery Plan (1995) is to develop ways to effectively monitor bats to define distributions and identify conservation needs for specific populations: this would better focus bat management and conservation strategies. My research objectives were to: monitor the spatial and temporal activity patterns of long-tailed bats (Chalinolobus tuberculatus; LTBs) at two exotic forest fragments on the edge (Hammond Bush) and outskirts (an oak fragment) of Hamilton City (North Island, New Zealand) and conduct a field-based playback experiment to assess whether aircraft noise alters bat activity. In Chapter 2, I monitored the spatial and temporal foraging activity of LTBs across different: nights; seasons; habitats; microhabitats (both vertical and horizontal dimensions); and varying environmental conditions, including an anthropogenic variable (frequency of aircraft overflights at the oak fragment). Foraging activity was variable over time, but nightly peaks occurred between the first and third hours after sunset. Pass rates were significantly higher at both habitats during spring and summer compared with winter. At the oak fragment, significantly more bat detections were recorded when detectors were placed at a height of 4-7m (compared with 15-30m); a similar non-significant trend was observed at Hammond Bush. A greater proportion of bat passes were recorded in microhabitats containing water bodies and open spaces. Mean nightly temperature was the only significant positive predictor of bat activity (at the oak fragment only). To maximise LTB detections in future monitoring studies so that resources can be better focused, I recommend that bats be monitored: 1.) during warmer months; 2.) on warmer nights; 3.) by placing detectors at heights of 4-7m; and 4.) by placing detectors in forested habitats near open spaces and water bodies. In Chapter 3, I concurrently monitored LTB activity at four rural and urban sites over three consecutive seasons and conducted a presence/absence survey at 11 sites along the rural-urban interface of Hamilton City. I sought to apply monitoring recommendations at different habitats and determine how LTBs are distributed in relation to distance from anthropogenic structures (e.g. roads and houses) and riparian margins. LTBs used multiple rural and urban sites across successive seasons; however, bat activity was lower at sites not situated adjacent to the Waikato River compared with sites on the riverbank. I detected LTBs at eight of 11 sites surveyed confirming that this species is more widely distributed in the Hamilton region than previously shown. I did not detect bats at urban sites surrounded by roads and houses. Both proximity to riverine habitat and anthropogenic structures (e.g. roads) may influence LTB distribution and habitat use. In Chapter 4, I showed that in addition to echolocation pulses, bat detectors also record some in-flight LTB calls. I classified LTB calls and tracked three common call types (chirps, pulses and buzzes) over the LTB breeding season (December-March). Pulses and buzzes were recorded around the time of female pregnancy to lactation, and lactation to juvenile volancy, respectively. These calls were only recorded at the oak fragment and were often associated with multi-bat echolocation sequences. Pulses and buzzes may be situation-specific social calls mediating interactions between reproductive females. Chirps were frequently recorded (89% of calls were chirps) across all months at both sites. Chirps may be more generally associated with foraging behaviour (e.g. aiding echo discrimination) as peaks in chirps overlapped with foraging activity. Tracking in-flight calls should alert researchers to sites of likely social importance to LTBs. Call function/s should be further investigated using playback experiments. In Chapter 5, I used a combination of correlative and experimental playback methods to investigate whether aircraft activity and noise alters the evening activity of free-living LTBs. Correlative data revealed that low-altitude aircraft activity overlapped with bat activity at the oak fragment. Bat activity decreased during and after aircraft passes but this trend was not statistically significant. It also appears that bats decrease their activity more during louder aircraft passes. Playback trials revealed that simulated aircraft noise did not significantly alter bat behaviour compared with baseline activity levels and a silent control. Results suggest that aircraft noise may not disturb LTB behaviour or mask high frequency echolocation pulses

Maintaining and perpetuating habitat structures for wildlife in modified landscapes

Landscape modification is a major global threat to terrestrial biodiversity. Managing human-modified landscapes in ecologically sustainable ways is crucial to avoid and mitigate biodiversity loss. However, practitioners (e.g. policymakers and developers) still urgently require research to inform targeted habitat protection policies, on-the-ground land management practices, and biodiversity offset strategies. My research focused on identifying ways to strategically maintain and perpetuate habitat structures for wildlife in modified landscapes. I had three objectives: (1) measure and compare the current and future availability of habitat structures; (2) quantify the biodiversity value of scattered trees; and (3) test the effectiveness of artificial nest boxes as a biodiversity offset tool. First, I conducted vegetation surveys at 300 plots in three dominant landscape contexts (reserves, pasture, urban greenspace). I found that in urban greenspace, the availability of multiple habitat structures (e.g. trees, logs, shrubs) depended upon by biota were significantly reduced compared with reserves, but comparable with agricultural land. Using a simulation model for tree populations, I also found that hollow-bearing trees were predicted to decline by an average of 87% in urban greenspace over the next 300 years under existing tree management policies. I identified that only a combination of tree management approaches can arrest this decline. Second, I completed wildlife surveys at 72 individual trees of three sizes (small, medium, large) located in four landscape contexts (reserves, pasture, urban parklands, urban built-up areas). I recorded high invertebrate, bat and bird abundance and richness at scattered trees, representing a diversity of functional guilds. Furthermore, the biodiversity value of scattered trees in modified landscapes, including even small trees, was comparable or greater than that of trees located in reserves. I also found that several smaller trees could provide habitat compensation equivalent to that of a single large tree for some bird species and in certain landscape contexts (reserves and urban built-up areas). However, this was not a suitable offset strategy for a quarter of bird species and in other landscape contexts (pasture and urban parklands). Finally, I conducted an experiment using 144 nest boxes with different entrance sizes (20, 35, 55, 75, 95 and 115 mm), secured to trees of three sizes (small, medium, large) located in four landscape contexts (reserves, pasture, urban parklands, urban built-up areas). I found that adding nest boxes to large trees resulted in an increase in tree visitation by hollow-nesting birds. However, the same response was not observed at small, medium or control trees. Nest boxes were also only occupied by common native and exotic species and are thus unlikely to be effective at ameliorating the residual impacts of hollow-bearing tree removal, especially for threatened taxa. Based on my collective findings, I recommend: (1) adopting spatial zoning tactics that aim to resolve human-habitat conflicts and retain multiple habitat structures; (2) prioritising the conservation of scattered trees over the long-term by balancing both re-vegetation and mature tree preservation strategies; and (3) exercising caution in the wide-scale application of nest box offsets. These recommendations could assist practitioners in establishing more biodiversity-sensitive modified landscapes

The value of scattered trees for wildlife: Contrasting effects of landscape context and tree size

Aim: The biodiversity value of scattered trees in modified landscapes is often overlooked in planning and conservation decisions. We conducted a multitaxa study to determine how wildlife abundance, species richness and community composition at individual trees are affected by (1) the landscape context in which trees are located; and (2) the size of trees. Location: Canberra, south-eastern Australia. Methods: Trunk arthropod, bat and bird surveys were undertaken over 3 years (2012–2014) at 72 trees of three sizes (small (20–50 cm DBH), medium (51–80 cm), large (≥80 cm)) located in four landscape contexts (reserves, pasture, urban parklands, urban built-up areas). Results: Landscape context affected all taxa surveyed. Trunk arthropod communities differed between trees in urban built-up areas and reserves. Bat activity and richness were significantly reduced at trees in urban built-up areas suggesting that echolocating bats may be disturbed by high levels of urbanization. Bird abundance and richness were highest at trees located in modified landscapes, highlighting the value of scattered trees for birds. Bird communities also differed between non-urban and urban trees. Tree size had a significant effect on birds but did not affect trunk arthropods and bats. Large trees supported higher bird abundance, richness and more unique species compared to medium and small trees. Main conclusions: Scattered trees support a diversity of wildlife. However, landscape context and tree size affected wildlife in contrasting ways. Land management strategies are needed to collectively account for responses exhibited by multiple taxa at varying spatial scales. We recommend that the retention and perpetuation of scattered trees in modified landscapes should be prioritized, hereby providing crucial habitat benefits to a multitude of taxa.DSL was funded by an Australian Postgraduate Award (The Australian National University) and a top-up scholarship (Land Development Agency, ACT Government). Land Development Agency, ACT Government; Australian Research Council, Grant/Award Number: FT100100358; Fenner School of Environment and Society, Australian National Universit

Trends and predictions of malnutrition and obesity in 204 countries and territories: an analysis of the Global Burden of Disease Study 2019.

BackgroundMalnutrition and obesity are interdependent pathologies along the same spectrum. We examined global trends and projections of disability-adjusted life years (DALYs) and deaths from malnutrition and obesity until 2030.MethodsUsing data from the 2019 Global Burden of Disease study involving 204 countries and territories, trends in DALYs and deaths were described for obesity and malnutrition from 2000 to 2019, stratified by geographical regions (as defined by WHO) and Socio-Demographic Index (SDI). Malnutrition was defined according to the 10th revision of International Classification of Diseases codes for nutritional deficiencies, stratified by malnutrition type. Obesity was measured via body mass index (BMI) using metrics related to national and subnational estimates, defined as BMI ≥25 kg/m2. Countries were stratified into low, low-middle, middle, high-middle, and high SDI bands. Regression models were constructed to predict DALYs and mortality up to 2030. Association between age-standardised prevalence of the diseases and mortality was also assessed.FindingsIn 2019, age-standardised malnutrition-related DALYs was 680 (95% UI: 507-895) per 100,000 population. DALY rates decreased from 2000 to 2019 (-2.86% annually), projected to fall 8.4% from 2020 to 2030. Africa and low SDI countries observed highest malnutrition-related DALYs. Age-standardised obesity-related DALY estimates were 1933 (95% UI: 1277-2640). Obesity-related DALYs rose 0.48% annually from 2000 to 2019, predicted to increase by 39.8% from 2020 to 2030. Highest obesity-related DALYs were in Eastern Mediterranean and middle SDI countries.InterpretationThe ever-increasing obesity burden, on the backdrop of curbing the malnutrition burden, is predicted to rise further.FundingNone

The bii4africa dataset of faunal and floral population intactness estimates across Africa’s major land uses

Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species’ population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate ‘intactness scores’: the remaining proportion of an ‘intact’ reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region’s major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/ taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems

Do long-tailed bats alter their evening activity in response to aircraft noise?

Human-generated noise may alter animal activity patterns and mask vocal signals. We used field-based observations and a playback experiment to investigate whether aircraft activity and noise alter the evening activity of New Zealand long-tailed bats (Chalinolobus tuberculatus) a cryptic threatened species. Low-altitude aircraft activity temporally overlapped bat activity near the runway of an international airport, but was unlikely to mask echolocation pulses as aircraft noise was most intense at ≤ 10 kHz. There was no statistically significant difference in mean bat activity during and after overflights compared with pre-aircraft activity. The experiment revealed that playback stimuli (aircraft passes and two controls: silent tracks and blackbird (Turdus merula) calls) differed in their effect on bat activity at two sites, one with low and one with high aircraft activity. Simulated aircraft noise and silent tracks reduced bat activity when compared with blackbird calls (P < 0.05). Bats may have found it easier to detect observers during the playback of silent tracks (sampling involved walking circuits with hand-held detectors), and may have reduced activity to a perceived threat. This result suggests that broadcasted aircraft noise is no more disturbing than researcher presence during playback trials. Evidence for a site × playback stimuli interaction (P = 0.054) suggests that bats at the site with high aircraft activity may have habituated to aircraft noise. Both correlative and experimental data suggests that aircraft activity and noise may not have major impacts on long-tailed bat activity

Single large or several small? Applying biogeographic principles to tree-level conservation and biodiversity offsets

Land development contributes to the clearance of large trees that are sometimes offset with many smaller trees as compensatory wildlife habitat. But are many smaller trees a valid biodiversity offset for the loss of a single large tree? To answer this question, we tested predictions underpinned by island biogeography theory. Targeting birds, we investigated size and landscape context effects at 72 trees of three sizes (small, medium, and large) located in four landscape contexts (reserves, pasture, urban parklands, and urban built-up areas). Significant positive relationships occurred between tree basal area and bird abundance and species richness in all landscape contexts. SLOSS (single large or several small) analysis revealed that in modified landscapes, several small and medium trees supported an equivalent number of individuals and species as a single large tree, but the same pattern was weaker in reserves. Extrapolated rarefaction curves revealed that in reserves and urban built-up areas, many small or medium trees accumulated the same number or more species than large trees. However, in pasture and urban parklands, many small or medium trees accumulated fewer species than large trees. Overall, 29% of bird species were recorded only at large trees, highlighting that many smaller trees will not be suitable habitat compensation for all species. Complementary approaches to biodiversity offsets are needed, balancing large tree preservation and revegetation. Response patterns for birds at trees conformed to some biogeographic predictions (species-area relationship), but not others (habitat-isolation relationship), underscoring the need for novel conceptual frameworks for habitat structures in modified landscapes

Combining historical remote sensing, digital soil mapping and hydrological modelling to produce solutions for infrastructure damage in Cosmo City, South Africa

Urbanization and hydrology have an interactive relationship, as urbanization changing the hydrology of a system and the hydrology commonly causing structural damage to the infrastructure. Hydrological modelling has been used to quantify the water causing structural impacts, and to provide solutions to the issues. However, in already-urbanized areas, creating a soil map to use as input in the modelling process is difficult, as observation positions are limited and visuals of the natural vegetation which indicate soil distribution are unnatural. This project used historical satellite images in combination with terrain parameters and digital soil mapping methods to produce an accurate (Kappa statistic = 0.81) hydropedology soil map for the Cosmo City suburb in Johannesburg, South Africa. The map was used as input into the HYDRUS 2D and SWAT hydrological models to quantify the water creating road damage at Kampala Crescent, a road within Cosmo City (using HYDRUS 2D), as well as the impact of urbanization on the hydrology of the area (using SWAT). HYDRUS 2D modelling showed that a subsurface drain installed at Kampala Crescent would need a carrying capacity of 0.3 m3·h−1·m−1 to alleviate the road damage, while SWAT modelling shows that surface runoff in Cosmo City will commence with as little rainfall as 2 mm·month−1. This project showcases the value of multidisciplinary work. The remote sensing was invaluable to the mapping, which informed the hydrological modelling and subsequently provided answers to the engineers, who could then mitigate the hydrology-related issues within Cosmo Ci

Reduced availability of habitat structures in urban landscapes: Implications for policy and practice

Over half the world's population resides in cities, with increasing trends towards urbanisation expected to continue globally over the next 50 years. Urban landscapes will be more ecologically sustainable where key habitat structures (e.g. trees, shrubs and woody debris) that support multiple taxa are maintained. Yet, there is little empirical data on the extent to which habitat structures have been modified in urban landscapes. Obtaining these data is a necessary first step towards reducing the ecological impacts of urbanisation. This is because urban practitioners can use this information to formulate more targeted management policies and conservation strategies that seek to better maintain and perpetuate habitat structures in urban landscapes. We compared the availability of multiple habitat structures in urban greenspace, agricultural land, and semi-natural reserves in Canberra, southeastern Australia. In urban greenspace, the density and/or probability of occurrence of trees, seedlings, dead trees, hollow-bearing trees, hollows, logs and native ground and mid-storey vegetation were significantly lower compared with reserves, but comparable with agricultural land. Our results highlight an urgent need for improved habitat protection policies, management strategies, and on-the-ground conservation actions that aim to retain and restore key habitat structures in urban landscapes. To achieve this requires innovative strategies that balance socio-economic priorities and biodiversity conservation. We propose three strategies that can be practically implemented in cities worldwide including: (1) establishing dedicated conservation areas; (2) spatially zoning habitat structures hazardous to humans within existing urban greenspaces, and (3) educating key stakeholders about the importance of habitat structures within urban environments

Key lessons for achieving biodiversity-sensitive cities and towns

Australia's urban landscapes offer opportunities to marry socio-economic and biodiversity conservation objectives. Yet, information is needed on what urban landscape and habitat features are important for wildlife. In this article, we draw together our research from southeastern Australia to describe key lessons for biodiversity-sensitive cities and towns. Lesson 1: The effects of urbanization on wildlife extend into adjacent habitats. We recommend retaining large, undisturbed areas of habitat away from development, avoiding intensive development adjacent to important conservation areas, prioritizing areas of ecological and social significance, screening light and noise pollution at the urban fringe and around large nature reserves, and planting appropriately provenanced locally native species for public streetscapes, parks and gardens. Lesson 2: Strategic enhancement of urban greenspace offers biodiversity gains. We recommend increasing the total amount of greenspace cover, maintaining ecological structures as habitat islands, using landscaping techniques to minimize risks to human safety, and gardening with low-flowering native shrubs. Lesson 3: Large old trees need to be managed for long-term sustainability. We recommend retaining large old trees in new developments, increasing the maximum standing life of urban trees, protecting regenerating areas and planting more seedlings, supplementing habitat features associated with large trees, and ensuring that young trees have space to grow through time. Lesson 4: Education and engagement connects residents with nature and raises awareness. We recommend education programs to enhance opportunities for residents to experience and learn about biodiversity, engaging residents in the establishment and maintenance of wildlife habitat, providing 'cues to care', facilitating access to garden plants that benefit wildlife, and encouraging cat containment. These lessons provide an evidence-base for implementing conservation and management actions to improve the capacity of our cities and towns to support a diverse and abundant biota