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

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

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

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

Background Malnutrition 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. Methods Using 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. Findings In 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. Interpretation The ever-increasing obesity burden, on the backdrop of curbing the malnutrition burden, is predicted to rise further.</p