Habitat explained microgeographic variation in Little Penguin agonistic calls

2021

Ibis

Species that are constantly exposed to disturbances, such as human disturbance or nonlethal contacts with predators or conspecifics, can experience chronic stress. Within a species range, variation in the frequency and predictability of such disturbances can lead to population differences in stress responses. Here, we investigated the stress response of Little Penguins Eudyptula minor to an introduced predator and a conspecific at two South Australian colonies that differed in habitat, conspecific density, levels of human disturbance and predation risk (high, low). We used playback experiments of Cat Felis catus or Little Penguin calls and recorded the behaviour and physiological (heart rate) response of adults in relation to playback type (Cat, Penguin) as well as habitat characteristics (habitat type, nest type, nest visibility) and number of conspecifics present. Our results showed that individuals from the high-disturbance colony (also living in a mixed habitat with fewer neighbours) exhibited higher vigilance and heart rate responses than individuals from the low-disturbance colony (living in a closed habitat with a high number of neighbours). Our results highlight that guidelines for managing penguin species cannot be generalized across populations and need to be colony-specific.

Section: Playback Experimentsmentioning

confidence: 99%

Behavioural and heart rate responses to stressors in two populations of Little Penguins that differ in levels of human disturbance and predation risk

Schaefer

2021

Ibis

“…), as found in other nocturnal seabirds (Landers et al 2011, Buxton & Jones 2012, Brownlie et al 2020. Brays and growls are their most common vocalizations (Miyazaki & Waas 2003, Colombelli-N egrel & Smale 2017) and hence are the focus of this study.…”

Section: Study Sites and Speciesmentioning

confidence: 84%

“…2020). Brays and growls are their most common vocalizations (Miyazaki & Waas 2003, Colombelli‐Négrel & Smale 2017) and hence are the focus of this study.…”

Section: Methodsmentioning

confidence: 99%

Estimating Little Penguin population sizes using automated acoustic monitoring and citizen science

2023

Ibis

While automated recorders are becoming a favourable tool to monitor birds, methods to analyse the large amount of data generated and their reliability for estimating population size are still limited. In this study, I compared Little Penguins Eudyptula minor call detection between a trained researcher, amateur volunteers and an automated software, assessed which environmental factors affect call variability and detectability and determined the feasibility of automated recorders to estimate population sizes. I found that (1) the number of calls detected by the trained researcher was significantly higher than those detected by the amateur volunteers and automated software, (2) neither wind speed nor moon illumination affected call variability and detectability, and (3) six automated recorders estimated between 3% (large colony) and 14–26% (small colony) of the population. This study contributes to our understanding of the efficacy of automated recorders for avian monitoring.

“…Little Penguins are very territorial (Waas 1990, 1991) and vocalize mainly at night. Bray and growl calls are the most common vocalizations and are used for territory defence, mate attraction and communication between partners (Miyazaki & Waas 2003, Colombelli‐Négrel & Smale 2018); hence, in this study, we focused on these calls. We constructed recognizers for Little Penguin bray and growl calls with the following parameters: (1) frequency range 50–1500 Hz, (2) minimum and maximum length of detection 0.1 and 7.5 s, respectively, and (3) maximum inter‐syllable gap 0.1 s. The software accuracy was 86% on Granite Island for Little Penguin calls (Colombelli‐Négrel 2023).…”

Section: Methodsmentioning

confidence: 99%

“…Yet this was under a strong suppression effect, suggesting an interactive effect with other human activities. Therefore, it is still possible that Little Penguins produced more calls at night when Dogs were present (as Dogs would always be accompanied by their owners and thus people) to compete with a noisy environment (Little Penguins do not have alarm calls, and we recorded brays and growls, which are used for communication between partners; Miyazaki & Waas 2003, Colombelli-N egrel & Smale 2018. This idea is further supported by the fact that Little Penguins also vocalized more when concerts occurred or when wind speeds increased, both of which would increase background noise.…”

Section: Modelmentioning

confidence: 99%

Human activities at night negatively impact Little Penguin (Eudyptula minor) numbers and behaviours

Costello

2023

Ibis

The presence of humans within the natural environment is increasing worldwide. Assessing the impact of such activities on wildlife is crucial for declining populations where human disturbance adds to existing pressures. Here, we investigated how human activities at night influenced Little Penguin Eudyptula minor numbers and behaviours (specifically return time, number of vocalizations and time spent in vigilance) on Granite Island, a declining population in South Australia, Australia. We combined data from regular night surveys with continuous video and audio monitoring to assess the impact of human activities on the Little Penguins. The use of white light (i.e. from torches or camera flashes) by people was the most frequent activity recorded at night (recorded on 65% of the monitored nights). Fewer penguins were found on land at night when Dogs Canis lupus familiaris were present, but not when the number of people increased, when concerts occurred, or when white lights were used. Little Penguins were observed more often returning late from sea at night when Dogs were present and when white lights were used, but not when concerts occurred. An increase in penguin vocalizations at night correlated with the presence of Dogs and the occurrence of concerts, whereas penguins vocalized less when white lights were used. The time Little Penguins spent in vigilance did not correlate with any of the disturbances analysed. Our study also highlights the impact of coronavirus disease 2019 (COVID‐19) on wildlife, as the occurrence of human activities increased significantly following the implementation of the COVID‐19 health protection measures. These results add to a growing body of literature suggesting that human activities on land, and their consequent disturbance(s), may affect the numbers and behaviours of wildlife and that appropriate measures need to be developed to limit such impacts.