Social foraging strategies and their association with learning and innovation abilities have been... more Social foraging strategies and their association with learning and innovation abilities have been studied extensively in flocking birds, but their importance for cooperatively breeding birds has remained relatively unexplored. The high degree of sociality typical of cooperative societies may indicate an important role of social foraging for learning and innovation. We studied 1) social foraging strategies and 2) the acquisition of a novel foraging skill in 16 groups of wild, cooperatively breeding Arabian babblers (Turdoides squamiceps). In Experiment 1, we provided a foraging grid of 96 feeding wells to each group, allowing them either to search for food individually (producer) or to join other birds (scrounger). Subordinates scrounged significantly more than dominant individuals, spent longer on the foraging grid, and had a higher proportion of their foraging steps rewarded (due to the effect of successful scrounging). However, scrounging was not related to poor learning ability because almost all the individuals that learned the novel foraging skill in Experiment 2 (removing a rubber lid to reach food) were scroungers. These findings suggest that group members differ in their foraging strategies and learning abilities according to their rank and that subordinate group members may be more opportunistic and flexible in their behavior than dominants, making use of both scrounging and novel foraging opportunities.
Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a perio... more Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a period over which significant range shifts have been observed in some indigenous bird species. We asked whether these range shifts by birds are clearly consistent with either climate change or land use change being the primary driver. Location South Africa. Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges. Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings. Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as ecological processes that influence habitat suitability.
Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a perio... more Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a period over which significant range shifts have been observed in some indigenous bird species. We asked whether these range shifts by birds are clearly consistent with either climate change or land use change being the primary driver. Location South Africa. Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges. Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings. Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as ecological processes that influence habitat suitability.
Sentinel behaviour, where individuals take turns to watch for danger and give alarm calls to appr... more Sentinel behaviour, where individuals take turns to watch for danger and give alarm calls to approaching predators, has been observed in a number of animal societies. However, the evolutionary causes of this behaviour remain unclear. There are two main, competing hypotheses regarding the evolution of sentinel behaviour. The first hypothesis is that it is a cooperative behaviour, where group members benefit from the detection of danger but share the workload of acting as a sentinel. The second is that it is a safe, selfish behaviour. Under the second hypothesis, once an individual is satiated, being a sentinel is safer because sentinels can detect threats more readily and can therefore escape from predators faster. We examined whether sentinels are safer than foragers in a wild, free-living cooperative bird (the pied babbler, Turdoides bicolor) with a well-described sentinel system. We found that sentinel behaviour was costly because (1) sentinels were targeted by predators more often, (2) they were further from cover than foragers, and (3) they took longer to reach the safety of cover following a predator alarm. These results suggest that individuals do not become sentinels because it is safer. This is the first study to demonstrate that sentinels are at greater risk of predator attack than foraging group members and suggests sentinel activity may have evolved as a form of cooperative behaviour.
Eavesdropping behaviour can increase the total amount of information available to an individual... more Eavesdropping behaviour can increase the total amount of information available to an individual and therefore has the potential to provide substantial benefits. Recent research has suggested that some species are ‘information givers’, particularly social species with cooperative vigilance systems, and that these species may consequently affect community structure by influencing the behaviour and niche utilization of other species.
Here, using behavioural observations and playback experiments, we compared the behavioural change in a solitary species (the scimitarbill) and a social species (the pied babbler), to the presence and alarm calls of one another.
Our results revealed that scimitarbills underwent significant behavioural changes in the presence of social pied babblers: they reduced their vigilance rate by over 60%, increased their foraging efficiency and expanded their niche by moving into open habitat and excavating subterranean food items. In contrast, pied babblers – who have an effective intraspecific sentinel system – did not show significant behavioural changes to the presence or alarm calls of scimitarbills.
These results suggest that interspecific interceptive eavesdropping can provide significant benefits, influencing the behaviour and habitat utilization of eavesdropping species.
Social foraging strategies and their association with learning and innovation abilities have been... more Social foraging strategies and their association with learning and innovation abilities have been studied extensively in flocking birds, but their importance for cooperatively breeding birds has remained relatively unexplored. The high degree of sociality typical of cooperative societies may indicate an important role of social foraging for learning and innovation. We studied 1) social foraging strategies and 2) the acquisition of a novel foraging skill in 16 groups of wild, cooperatively breeding Arabian babblers (Turdoides squamiceps). In Experiment 1, we provided a foraging grid of 96 feeding wells to each group, allowing them either to search for food individually (producer) or to join other birds (scrounger). Subordinates scrounged significantly more than dominant individuals, spent longer on the foraging grid, and had a higher proportion of their foraging steps rewarded (due to the effect of successful scrounging). However, scrounging was not related to poor learning ability because almost all the individuals that learned the novel foraging skill in Experiment 2 (removing a rubber lid to reach food) were scroungers. These findings suggest that group members differ in their foraging strategies and learning abilities according to their rank and that subordinate group members may be more opportunistic and flexible in their behavior than dominants, making use of both scrounging and novel foraging opportunities.
Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a perio... more Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a period over which significant range shifts have been observed in some indigenous bird species. We asked whether these range shifts by birds are clearly consistent with either climate change or land use change being the primary driver. Location South Africa. Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges. Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings. Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as ecological processes that influence habitat suitability.
Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a perio... more Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a period over which significant range shifts have been observed in some indigenous bird species. We asked whether these range shifts by birds are clearly consistent with either climate change or land use change being the primary driver. Location South Africa. Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges. Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings. Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as ecological processes that influence habitat suitability.
Sentinel behaviour, where individuals take turns to watch for danger and give alarm calls to appr... more Sentinel behaviour, where individuals take turns to watch for danger and give alarm calls to approaching predators, has been observed in a number of animal societies. However, the evolutionary causes of this behaviour remain unclear. There are two main, competing hypotheses regarding the evolution of sentinel behaviour. The first hypothesis is that it is a cooperative behaviour, where group members benefit from the detection of danger but share the workload of acting as a sentinel. The second is that it is a safe, selfish behaviour. Under the second hypothesis, once an individual is satiated, being a sentinel is safer because sentinels can detect threats more readily and can therefore escape from predators faster. We examined whether sentinels are safer than foragers in a wild, free-living cooperative bird (the pied babbler, Turdoides bicolor) with a well-described sentinel system. We found that sentinel behaviour was costly because (1) sentinels were targeted by predators more often, (2) they were further from cover than foragers, and (3) they took longer to reach the safety of cover following a predator alarm. These results suggest that individuals do not become sentinels because it is safer. This is the first study to demonstrate that sentinels are at greater risk of predator attack than foraging group members and suggests sentinel activity may have evolved as a form of cooperative behaviour.
Eavesdropping behaviour can increase the total amount of information available to an individual... more Eavesdropping behaviour can increase the total amount of information available to an individual and therefore has the potential to provide substantial benefits. Recent research has suggested that some species are ‘information givers’, particularly social species with cooperative vigilance systems, and that these species may consequently affect community structure by influencing the behaviour and niche utilization of other species.
Here, using behavioural observations and playback experiments, we compared the behavioural change in a solitary species (the scimitarbill) and a social species (the pied babbler), to the presence and alarm calls of one another.
Our results revealed that scimitarbills underwent significant behavioural changes in the presence of social pied babblers: they reduced their vigilance rate by over 60%, increased their foraging efficiency and expanded their niche by moving into open habitat and excavating subterranean food items. In contrast, pied babblers – who have an effective intraspecific sentinel system – did not show significant behavioural changes to the presence or alarm calls of scimitarbills.
These results suggest that interspecific interceptive eavesdropping can provide significant benefits, influencing the behaviour and habitat utilization of eavesdropping species.
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but their importance for cooperatively breeding birds has remained relatively unexplored. The high degree of sociality typical of cooperative
societies may indicate an important role of social foraging for learning and innovation. We studied 1) social foraging strategies
and 2) the acquisition of a novel foraging skill in 16 groups of wild, cooperatively breeding Arabian babblers (Turdoides squamiceps).
In Experiment 1, we provided a foraging grid of 96 feeding wells to each group, allowing them either to search for food individually
(producer) or to join other birds (scrounger). Subordinates scrounged significantly more than dominant individuals, spent longer on
the foraging grid, and had a higher proportion of their foraging steps rewarded (due to the effect of successful scrounging). However,
scrounging was not related to poor learning ability because almost all the individuals that learned the novel foraging skill in Experiment
2 (removing a rubber lid to reach food) were scroungers. These findings suggest that group members differ in their foraging strategies
and learning abilities according to their rank and that subordinate group members may be more opportunistic and flexible in their
behavior than dominants, making use of both scrounging and novel foraging opportunities.
Location South Africa.
Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges.
Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings.
Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not
least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas
anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as
ecological processes that influence habitat suitability.
Location South Africa.
Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges.
Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings.
Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not
least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas
anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as
ecological processes that influence habitat suitability.
Here, using behavioural observations and playback experiments, we compared the behavioural change in a solitary species (the scimitarbill) and a social species (the pied babbler), to the presence and alarm calls of one another.
Our results revealed that scimitarbills underwent significant behavioural changes in the presence of social pied babblers: they reduced their vigilance rate by over 60%, increased their foraging efficiency and expanded their niche by moving into open habitat and excavating subterranean food items. In contrast, pied babblers – who have an effective intraspecific sentinel system – did not show significant behavioural changes to the presence or alarm calls of scimitarbills.
These results suggest that interspecific interceptive eavesdropping can provide significant benefits, influencing the behaviour and habitat utilization of eavesdropping species.
but their importance for cooperatively breeding birds has remained relatively unexplored. The high degree of sociality typical of cooperative
societies may indicate an important role of social foraging for learning and innovation. We studied 1) social foraging strategies
and 2) the acquisition of a novel foraging skill in 16 groups of wild, cooperatively breeding Arabian babblers (Turdoides squamiceps).
In Experiment 1, we provided a foraging grid of 96 feeding wells to each group, allowing them either to search for food individually
(producer) or to join other birds (scrounger). Subordinates scrounged significantly more than dominant individuals, spent longer on
the foraging grid, and had a higher proportion of their foraging steps rewarded (due to the effect of successful scrounging). However,
scrounging was not related to poor learning ability because almost all the individuals that learned the novel foraging skill in Experiment
2 (removing a rubber lid to reach food) were scroungers. These findings suggest that group members differ in their foraging strategies
and learning abilities according to their rank and that subordinate group members may be more opportunistic and flexible in their
behavior than dominants, making use of both scrounging and novel foraging opportunities.
Location South Africa.
Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges.
Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings.
Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not
least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas
anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as
ecological processes that influence habitat suitability.
Location South Africa.
Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges.
Results Fifty-six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate-change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human-modified elements in the landscape, such as croplands, plantations or buildings.
Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not
least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas
anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as
ecological processes that influence habitat suitability.
Here, using behavioural observations and playback experiments, we compared the behavioural change in a solitary species (the scimitarbill) and a social species (the pied babbler), to the presence and alarm calls of one another.
Our results revealed that scimitarbills underwent significant behavioural changes in the presence of social pied babblers: they reduced their vigilance rate by over 60%, increased their foraging efficiency and expanded their niche by moving into open habitat and excavating subterranean food items. In contrast, pied babblers – who have an effective intraspecific sentinel system – did not show significant behavioural changes to the presence or alarm calls of scimitarbills.
These results suggest that interspecific interceptive eavesdropping can provide significant benefits, influencing the behaviour and habitat utilization of eavesdropping species.