Song learning in oscine songbirds : Tutor choice, timing, and the relationship with sexual imprinting

Birdsong is a species-specific signal that is used in mate attraction and intrasexual competition. This thesis concerns song acquisition in two oscine songbird species, the great tit Parus major and the pied flycatcher Ficedula hypoleuca. It addresses questions such as how free-living songbirds choose their song tutors and whether learning of foreign songs can take place in adult birds, and it looks into the relationship between song learning and sexual imprinting. This was done using a method of experimental, interspecific cross-fostering, in which eggs were swapped between nests of different species. Great tits were cross-fostered to blue tits Cyanistes caeruleus, and pied flycatchers were cross-fostered to great tits and blue tits. In oscine songbirds, young males have to learn their song from adult conspecifics, and a mechanism is needed to ensure that they choose song tutors of the right species. Early laboratory studies proposed the existence of an innate auditory template facilitating the recognition and memorization of conspecific song. However, in a number of species, males reared by heterospecifics have been found to copy songs of the foster species and thereby become mixed singers. To account for such heterospecific song learning, it has been suggested that familiarization with the social father before independence guides the choice of song tutors. However, under natural conditions, young males may grow up without a social father. A study on captive zebra finches Taeniopygia guttata has demonstrated effects of the social mother on song learning. Based on this finding, I propose a mechanism of mothermediated tutor choice, suggesting that experience with the social mother as well as the father guides the choice of song tutor in oscine songbirds. Great tits cross-fostered to blue tits include blue tit song in their repertoires. They also get sexually misimprinted, and occasional heterospecific pairs are formed between cross-fostered great tits and cross-fostered blue tits. I tested the hypothesis of mother-mediated tutor choice by letting great tits grow up with a blue tit foster mother and a great tit foster father. Males of this treatment included blue tit song in their repertoires. To control for the possibility that the males had learned the blue tit song directly from their cross-fostered fathers, we also recorded song from great tit males that were reared by conspecifics, but whose fathers had been cross-fostered to blue tits. None of these males sang blue tit song, suggesting an effect of the social mother. However, cross-fostered great tit males mated to blue tits may sing more blue tit song than those mated to great tits. Our samples were too small to separate between heterospecific song learning resulting from mother-mediated tutor choice and from exposure to blue tit song in the repertoire of the father. Song learning shares a number of characteristics with sexual imprinting. I investigated the relationship between these two processes in great tits. I exposed cross-fostered great tit males to playback of great tit song and blue tit song inside their territory. Males that showed sexual interest in blue tit females were more likely to respond with blue tit song to playback than males that showed interest only in conspecific females. This suggests that different degrees of misimprinting may have parallel effects on song learning and sexual preferences in cross-fostered great tit males. Furthermore, the response to territorial intruders seemed to be affected by social interactions: Cross-fostered males currently associated with blue tits increased their response to playback of blue tit song whereas males currently associated with great tits increased their response to playback of great tit song through the season. I also studied the effect of social rearing condition on song learning in pied flycatchers. Cross-fostered pied flycatchers do not seem to get sexually misimprinted. However, I found that pied flycatcher males reared by blue tits or great tits became mixed singers, uttering a combination of pied flycatcher song and the foster species’ song. Furthermore, males reared with nest mates of the foster species included tit song in a higher proportion of strophes than did cross-fostered males reared with conspecific nest mates. Hence, in pied flycatchers, growing up with heterospecific foster parents and nest mates caused a mixed choice of song tutors without affecting their mate preferences. Some songbird species are open-ended learners and retain the ability to learn new songs throughout their lives. However, to demonstrate that a species is a true open-ended learner, it is necessary to make sure that the elements learned as adults have not been heard and possibly memorized by the birds at an early age. I performed a playback experiment to test whether the pied flycatcher is a true open-ended learner. I exposed pied flycatcher males to playback of song containing syllables that were unknown to the study area. Among the 20 subjects, one yearling and two older males had learned a foreign syllable type, supporting the hypothesis that pied flycatchers are true open-ended learners. Pied flycatcher song is believed to serve mostly for mate attraction, and possible functions of adult song learning are to increase the repertoire size and to increase syllable sharing with neighbours. The subjects showed no increase in either of these parameters after the treatment. An alternative adaptive value of adult song learning in pied flycatchers may rather be to pick up particularly attractive song elements

What's in a word? Conflicting interpretations of vulnerability in climate change research

In this paper, we discuss two competing interpretations of vulnerability in the climate change literature and consider the implications for both research and policy. The first interpretation, which can be referred to as the “end point” approach, views vulnerability as a residual of climate change impacts minus adaptation. The second interpretation, which takes vulnerability as a “starting point,” views vulnerability as a general characteristic generated by multiple factors and processes. Viewing vulnerability as an end point considers that adaptations and adaptive capacity determine vulnerability, whereas viewing vulnerability as a starting point holds that vulnerability determines adaptive capacity. The practical consequences of these two interpretations are illustrated through the examples of Norway and Mozambique. We show that, if the underlying causes and contexts of vulnerability are not taken into account, there is a danger of underestimating the magnitude (large), scope (social and environmental) and urgency (high) of climate change

Environmental and anthropogenic features mediate risk from human hunters and wolves for moose

This is an open access article under the terms of theCreative Commons AttributionLicense, which permits use, distribution and reproduction in any medium, providedthe original work is properly cited. © 2022 The Authors.Ecospherepublished by Wiley Periodicals LLC on behalf of The Ecological Society of AmericaLandscape characteristics, seasonal changes in the environment, and daylight conditions influence space use and detection of prey and predators, resulting in spatiotemporal patterns of predation risk for the prey. When predators have different hunting modes, the combined effects of multiple predators are mediated by the physical landscape and can result in overlapping or contrasting patterns of predation risk. Humans have become super-predators in many anthropogenic landscapes by harvesting game species and competing with large carnivores for prey. Here, we used the locations of wolf (Canis lupus)-killed and hunter-killed moose (Alces alces) in south-central Scandinavia to investigate whether environmental and anthropogenic features influenced where wolves and hunters killed moose. We predicted that the combined effects of wolves and hunters would result in contrasting spatial risk patterns due to differences in hunting modes. We expected these contrasting spatial risk patterns also to differ temporally. During the hunting season, the probability of a wolf kill increased with distance to bogs, whereas it decreased with increasing building density and distance to clearcuts and young forests. After the hunting season, the probability of a wolf kill increased with increasing terrain ruggedness and decreased with increasing building density, distance to main roads, and distance to clearcuts and young forests. The probability of a hunter kill was highest closer to bogs, main and secondary roads, in less rugged terrain and in areas with lower building density. Hunters killed all moose during the day, whereas wolves killed most moose at night during and after the hunting season. Our findings suggest that environmental and anthropogenic features mediate hunting and wolf predation risk. Additionally, we found that hunter- and wolf-killed moose exhibited contrasting spatial associations to landscape features, most likely due to the different hunting modes displayed by hunters and wolves. However, wolf predation and hunting risks also contrasted over time since wolves killed mostly at night and hunters were restricted to hunting during daytime and during the hunting season. This temporal segregation in risk might therefore suggest that moose could minimize risk exposure by taking advantage of spatiotemporally vacant hunting domains.publishedVersio

Wolf Responses to Experimental Human Approaches Using High-Resolution Positioning Data

Humans pose a major mortality risk to wolves. Hence, similar to how prey respond to predators, wolves can be expected to show anti-predator responses to humans. When exposed to a threat, animals may show a fight, flight, freeze or hide response. The type of response and the circumstances (e.g., distance and speed) at which the animal flees are useful parameters to describe the responses of wild animals to approaching humans. Increasing knowledge about behavioral responses of wolves toward humans might improve appropriate management and decrease conflicts related to fear of wolves. We did a pilot study by conducting 21 approach trials on seven GPS-collared wolves in four territories to investigate their responses to experimental human approaches. We found that wolves predominantly showed a flight response (N = 18), in a few cases the wolf did not flee (N = 3), but no wolves were seen or heard during trials. When wolves were downwind of the observer the flight initiation distance was significantly larger than when upwind, consistent with the hypothesis that conditions facilitating early detection would result in an earlier flight. Our hypothesis that early detection would result in less intense flights was not supported, as we found no correlation between flight initiation distances and speed, distance, or straightness of the flight. Wolves in more concealed habitat had a shorter flight initiation distance or did not flee at all, suggesting that perceived risk might have been affected by horizontal visibility. Contrary to our expectation, resettling positions were less concealed (larger horizontal visibility) than the wolves’ initial site. Although our small number of study animals and trials does not allow for generalizations, this pilot study illustrates how standardized human approach trials with high-resolution GPS-data can be used to describe wolf responses at a local scale. In continuation, this method can be applied at larger spatial scales to compare wolf flight responses within and between populations and across anthropogenic gradients, thus increasing the knowledge of wolf behavior toward humans, and potentially improving coexistence with wolves across their range.publishedVersio

Wolf Responses to Experimental Human Approaches Using High-Resolution Positioning Data

Humans pose a major mortality risk to wolves. Hence, similar to how prey respond to predators, wolves can be expected to show anti-predator responses to humans. When exposed to a threat, animals may show a fight, flight, freeze or hide response. The type of response and the circumstances (e.g., distance and speed) at which the animal flees are useful parameters to describe the responses of wild animals to approaching humans. Increasing knowledge about behavioral responses of wolves toward humans might improve appropriate management and decrease conflicts related to fear of wolves. We did a pilot study by conducting 21 approach trials on seven GPS-collared wolves in four territories to investigate their responses to experimental human approaches. We found that wolves predominantly showed a flight response (N = 18), in a few cases the wolf did not flee (N = 3), but no wolves were seen or heard during trials. When wolves were downwind of the observer the flight initiation distance was significantly larger than when upwind, consistent with the hypothesis that conditions facilitating early detection would result in an earlier flight. Our hypothesis that early detection would result in less intense flights was not supported, as we found no correlation between flight initiation distances and speed, distance or straightness of the flight. Wolves in more concealed habitat had a shorter flight initiation distance or did not flee at all, suggesting that perceived risk might have been affected by horizontal visibility. Contrary to our expectation, resettling positions were less concealed (larger horizontal visibility) than the wolves' initial site. Although our small number of study animals and trials does not allow for generalizations, this pilot study illustrates how standardized human approach trials with high-resolution GPS-data can be used to describe wolf responses at a local scale. In continuation, this method can be applied at larger spatial scales to compare wolf flight responses within and between populations and across anthropogenic gradients, thus increasing the knowledge of wolf behavior toward humans, and potentially improving coexistence with wolves across their range

Spatial and temporal cohesion of parents and offspring in a social large carnivore

Social organization in animals is a fundamental factor driving population dynamics and individual spatial distribution. Affiliation among kin is common in social groups, but kinship is no safeguard against intraspecific competition. Within social groups, the closest competitors are often related. In this study, we present 14 years of GPS-position movement data from 65 pairs (i.e. breeding pair, pup-adult breeder and pup-pup) of Scandinavian wolves, Canis lupus. We investigated social behaviour by examining spatial and temporal patterns of cohesion through winter to early summer (January to July) including two key reproductive periods, mating and birth, using mixed regressive nonlinear time series analysis (GAMM). During the mating period, breeding wolf pairs remained cohesive, while offspring increasingly dissociated. Offspring became even more solitary until the next birth period, when most permanently left their natal pack and territory. We suggest that the social organization of wolves may be modulated by intraspecific competition related to social aggression during the mating period and food competition around the birthing period. Early independence followed by immediate natal dispersal may be advan-tageous to both offspring and parents if the chances of finding food and a breeding partner and settling in a vacant area are high.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY license (http://creativecommons.org/licenses/ by/4.0/)

Spatial and temporal cohesion of parents and offspring in a social large carnivore

Social organization in animals is a fundamental factor driving population dynamics and individual spatial distribution. Affiliation among kin is common in social groups, but kinship is no safeguard against intraspecific competition. Within social groups, the closest competitors are often related. In this study, we present 14 years of GPS-position movement data from 65 pairs (i.e. breeding pair, pup–adult breeder and pup–pup) of Scandinavian wolves, Canis lupus. We investigated social behaviour by examining spatial and temporal patterns of cohesion through winter to early summer (January to July) including two key reproductive periods, mating and birth, using mixed regressive nonlinear time series analysis (GAMM). During the mating period, breeding wolf pairs remained cohesive, while offspring increasingly dissociated. Offspring became even more solitary until the next birth period, when most permanently left their natal pack and territory. We suggest that the social organization of wolves may be modulated by intraspecific competition related to social aggression during the mating period and food competition around the birthing period. Early independence followed by immediate natal dispersal may be advantageous to both offspring and parents if the chances of finding food and a breeding partner and settling in a vacant area are high.publishedVersio

Daylength influences the response of three clover species (Trifolium spp.) to short-term ozone stress

-Long photoperiods characteristic of summers at high latitudes can increase ozone-induced foliar injury in subterranean clover (Trifolium subterraneum) This study compared the effects of long photoperiods on ozone injury in red and white clover cultivars adapted to shorter or longer daylengths of southern or northern Fennoscandia. Plants were exposed to 70 ppb ozone for six hours during the daytime for three consecutive days. Simultaneously, the daylength in the growth rooms was altered to long-day (10 h light; 14 h dim light) and short-day (10 h light; 14 h darkness) conditions. Thermal imaging showed that ozone disrupted leaf temperature and stomatal function, particularly in sensitive species, in which leaf temperature deviations persisted for several days after ozone exposure. Longday conditions increased visible foliar injury (30%–70%), characterized by chlorotic and necrotic areas, relative to short day conditions in all species and cultivars independently of the photoperiod in the region they were adapted to