Taxonomic Shifts in <em>Philornis</em> Larval Behaviour and Rapid Changes in <em>Philornis downsi</em> Dodge & Aitken (Diptera: Muscidae): An Invasive Avian Parasite on the Galápagos Islands

The parasitic larvae of Philornis downsi Dodge & Aitken (Diptera: Muscidae) were first discovered in Darwin’s finch nests on the Galápagos Islands in 1997. Larvae of P. downsi consume the blood and tissue of developing birds, causing high in-nest mortality in their Galápagos hosts. The fly has been spreading across the archipelago and is considered the biggest threat to the survival of Galápagos land birds. Here, we review (1) Philornis systematics and taxonomy, (2) discuss shifts in feeding habits across Philornis species comparing basal to more recently evolved groups, (3) report on differences in the ontogeny of wild and captive P. downsi larvae, (4) describe what is known about adult P. downsi behaviour, and (5) discuss changes in P. downsi behaviour since its discovery on the Galápagos Islands. From 1997 to 2010, P. downsi larvae have been rarely detected in Darwin’s finch nests with eggs. Since 2012, P. downsi larvae have regularly been found in the nests of incubating Darwin’s finches. Exploring P. downsi ontogeny and behaviour in the larger context of taxonomic relationships provides clues about the breadth of behavioural flexibility that may facilitate successful colonisation

Darwin’s finches in human-altered environments sing common song types and are more aggressive

Human-altered landscapes may act as an environmental filter benefiting species or individuals with specific sets of capacities or behaviors. Yet the effects of human activity on culturally transmitted traits in animals are still poorly understood. Combining song recordings and simulated territory intrusions, we investigated whether songs (a cultural trait) and aggressiveness (a personality trait) in small ground finches (Geospiza fuliginosa) differed along a gradient of human activity levels (high-low-high) spanning two habitats with contrasting levels of rainfall (arid lowlands, humid highlands). We found that more common syllable types were more prevalent in arid lowland sites and at sites with high human activity. The number of syllables per song, song duration, song tempo and song rhythmicity did not differ across habitats or levels of human activity. During simulated territorial intrusions, small ground finches living in areas with higher levels of human activity and in the arid lowlands (regardless of human activity) showed the strongest aggressive response compared to those living in areas with lower levels of human activity or in the humid highlands. Thus, prevalence of aggression and syllable commonness correlated with each other across sites. Our results support the idea that resource distribution and human-impacted environments may select jointly for specific behavioral phenotypes such as aggression as well as common cultural traits

Prenatal auditory learning in avian vocal learners and non-learners

Understanding when learning begins is critical for identifying the factors that shape both the developmental course and the function of information acquisition. Until recently, sufficient development of the neural substrates for any sort of vocal learning to begin in songbirds was thought to be reached well after hatching. New research shows that embryonic gene activation and the outcome of vocal learning can be modulated by sound exposure in ovo. We tested whether avian embryos across lineages differ in their auditory response strength and sound learning in ovo, which we studied in vocal learning (Maluridae, Geospizidae) and vocal non-learning (Phasianidae, Spheniscidae) taxa. While measuring heart rate in ovo, we exposed embryos to (i) conspecific or heterospecific vocalizations, to determine their response strength, and (ii) conspecific vocalizations repeatedly, to quantify cardiac habituation, a form of non-associative learning. Response strength towards conspecific vocalizations was greater in two species with vocal production learning compared to two species without. Response patterns consistent with non-associative auditory learning occurred in all species. Our results demonstrate a capacity to perceive and learn to recognize sounds in ovo, as evidenced by habituation, even in species that were previously assumed to have little, if any, vocal production learning. This article is part of the theme issue 'Vocal learning in animals and humans'

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

Dataset made available according to CC BY 4.0 Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/Dataset for report. Species that are constantly exposed to disturbances, such as human disturbance or non‐lethal 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 response. 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, conspecifics 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 generalised across populations and need to be colony‐specific

Data from: Superb fairy-wrens respond more to alarm calls from mate and kin compared to unrelated individuals

Variation in the acoustic structure of alarm signals has mainly been viewed as coding information about the type of predator or the level of threat posed by the predator. Alarm signals can also convey individuality information, but whether conspecifics use this information and the function of individually distinct alarm calls remains unclear. In this study, we examined whether mobbing alarm calls of superb fairy-wrens (Malurus cyaneus) communicated information about sex, individual identity or kinship and whether this information was stable between years. We then examined the discriminative abilities of adults using playback experiments. We first used a habituation/dishabituation procedure to investigate whether adults were able to differentiate between two unfamiliar individuals. Then, we tested whether they adjusted their response based on their level of familiarity or kinship with the caller by comparing their response to mobbing alarm calls of their mate, a first order relative from the same population, an unrelated individual from the same population, or a distant bird from a different population. Superb fairy-wren mobbing alarm calls conveyed information about individuality, but not sex or kinship, and vocal individuality varied between years. Adults discriminated between two unfamiliar individuals and responded more strongly to playback of calls from their mate and kin versus individuals from another population. We discussed the conditions for discrimination based on individual characteristics rather than categories of individuals

Breeding success in Southern Australian little penguins is negatively correlated with high wind speeds and sea surface temperatures

© 2020 Flinders Universit

Darwin’s finches in human-altered environments sing common song types and are more aggressive

Human-altered landscapes may act as an environmental filter benefiting species or individuals with specific sets of capacities or behaviors. Yet the effects of human activity on culturally transmitted traits in animals are still poorly understood. Combining song recordings and simulated territory intrusions, we investigated whether songs (a cultural trait) and aggressiveness (a personality trait) in small ground finches (Geospiza fuliginosa) differed along a gradient of human activity levels (high-low-high) spanning two habitats with contrasting levels of rainfall (arid lowlands, humid highlands). We found that more common syllable types were more prevalent in arid lowland sites and at sites with high human activity. The number of syllables per song, song duration, song tempo and song rhythmicity did not differ across habitats or levels of human activity. During simulated territorial intrusions, small ground finches living in areas with higher levels of human activity and in the arid lowlands (regardless of human activity) showed the strongest aggressive response compared to those living in areas with lower levels of human activity or in the humid highlands. Thus, prevalence of aggression and syllable commonness correlated with each other across sites. Our results support the idea that resource distribution and human-impacted environments may select jointly for specific behavioral phenotypes such as aggression as well as common cultural traits