Kasper Thorup - Academia.edu (original) (raw)

Papers by Kasper Thorup

How do geometric constraints influence migration patterns?-Null models exclusively invoking geome... more How do geometric constraints influence migration patterns?-Null models exclusively invoking geometric constraints have recently been demonstrated to provide new insight as to what explains geographic patterns of species richness and range size distribution. Analyses of migration patterns have traditionally been conducted in the absence of appropriate simulations and analytical models. Here we present a null model exclusively invoking geometric constraints and a more advanced analytical model incorporating spread along a migration direction that allow investigation of the influence of physiographical and physiological boundaries for terrestrial taxa, with ocean and sea as geometric constraints, in relation to observed patterns of migration. Our models take into account the low recovery probability of terrestrial taxa over sea. The null model was not found to explain any of the directional variation in the ring-recoveries, but when comparing the distribution of data modeled using a simple clock-and-compass model with distributions of ring-recoveries, geometric constraints were found to explain up to 22% of the variation in ring-recoveries. However, the assumed directional concentrations per step used in the model were much higher than expected, and the qualitative fit of the model was rather poor even when non-terrestrial sites of recoveries were excluded.

Western Phylloscopus bonelli and Eastern Bonelli's Warblers P. orientalis occur as vagrants i... more Western Phylloscopus bonelli and Eastern Bonelli's Warblers P. orientalis occur as vagrants in northwest Europe. Up until 2006, a total of ten Western and five Eastern Bonelli's warblers were recorded in Norway, Sweden and Finland. Only recently have the two taxa attained full species rank, primarily based on differ- ences in DNA, but also in differences in vocalization and minor

A number of possibilities exist for tracking the sometimes even global journeys undertaken by mig... more A number of possibilities exist for tracking the sometimes even global journeys undertaken by migrating birds. Birds fitted with radio transmitters can either be located from the ground or from aircraft (conventional satellite tracking), or from space. Alternatively, positional information obtained by onboard equipment (e.g. GPS units) can be transmitted to receivers in space. Using these tracking methods has provided biologists with a wealth of insight into the migration routes, stopovers and other behaviours in long-distance migrants that are otherwise very difficult to follow. This knowledge has important implicat ions for e.g. conservation and understanding disease transmission and effects of climate chang e. The weight of satellite radio transmitters complicates study of the majority of bird species, but the weight is likely to be greatly reduced in the near future.

... In birds, protandry has been widely reported (Ketterson and Nolan 1976; Myers 1981; Francis a... more ... In birds, protandry has been widely reported (Ketterson and Nolan 1976; Myers 1981; Francis and Cooke 1986; Otahal 1995), and long-term surveys ... Acknowledgments We wish to thank the numerous ringers col-lecting the data, and JM Lausten, P. Lyngs, J. Rabøl as well as ...

With the aim of quantifying spatio-temporal and social factors affecting territorial calls in Lit... more With the aim of quantifying spatio-temporal and social factors affecting territorial calls in Little Owls, we collected data on the calling behaviour of radio tracked individuals from a low-density population in Northern Jutland, Denmark. There was considerable seasonal variation in calling activity. During the breeding season, males calling away from the nest were located in the direction of the neighbouring nesting site, and males with a neighbour within hearing distance called more often than those with a longer distance to the nearest neighbour. Call posts were on average closer to the nest than telemetry observations, but did not appear to be related to mate distance. With a sound pressure level of 82 dB(A) at 1m distance, the territorial calls were estimated to be audible to a distance of 4.4 km. Call posts were on average 4.1 m above the ground, which probably maximizes the transmission distance.

Before dispersal, social and spatial behaviour in owls has only been briefly studied. We used rad... more Before dispersal, social and spatial behaviour in owls has only been briefly studied. We used radio tracking to monitor age-influenced social and spatial behaviour in 10 juvenile Little Owls (Athene noctua) from nests in Northern Jutland, Denmark. On average, the post-fledging dependency period lasted 35 days (n = 6). Juveniles stayed on the natal territory 45 days (n = 5) from independence to dispersal. Half of the juveniles had dispersed by mid-September, and the other half remained on the natal territory until at least mid-October. The home range size (minimum convex polygons) was 0.56 ± 0.53 ha (mean ± SD) from fledging to independence and 3.25 ± 4.15 ha from independence to dispersal. Within the first 40 days after fledging, the nightly distance from the nest and the distance between siblings increased, and the frequency and intensity of begging calls decreased. These results were consistent with the notion that food provided by the parents decreased as juvenile foraging skills increased.

Proceedings of the National Academy of Sciences of the United States of America, 2007

Billions of songbirds migrate several thousand kilometers from breeding to wintering grounds and ... more Billions of songbirds migrate several thousand kilometers from breeding to wintering grounds and are challenged with crossing ecological barriers and facing displacement by winds along the route. A satisfactory explanation of long-distance animal navigation is still lacking, partly because of limitations on field-based study. The navigational tasks faced by adults and juveniles differ fundamentally, because only adults migrate toward wintering grounds known from the previous year. Here, we show by radio tracking from small aircraft that only adult, and not juvenile, long-distance migrating white-crowned sparrows rapidly recognize and correct for a continent-wide displacement of 3,700 km from the west coast of North America to previously unvisited areas on the east coast. These results show that the learned navigational map used by adult long-distance migratory songbirds extends at least on a continental scale. The juveniles with less experience rely on their innate program to find their distant wintering areas and continue to migrate in the innate direction without correcting for displacement.

Ecology and Evolution, 2014

For the study of migratory connectivity, birds have been individually marked by metal rings for m... more For the study of migratory connectivity, birds have been individually marked by metal rings for more than 100 years. The resulting ring recovery data have been compiled in numerous bird migration atlases. However, estimation of what proportion of a particular population is migrating to which region is confounded by spatial heterogeneity in ring recovery probability. We present a product multinomial model that enables quantifying the continent-wide distribution of different bird populations during different seasons based on ring recovery data while accounting for spatial heterogeneity of ring recovery probability. We applied the model to an example data set of the European robin Erithacus rubecula. We assumed that ring recovery probability was equal between different groups of birds and that survival probability was constant. Simulated data indicate that violation of the assumption of constant survival did not affect our estimated bird distribution parameters but biased the estimates for recovery probability. Posterior predictive model checking indicated a good general model fit but also revealed lack of fit for a few groups of birds. This lack of fit may be due to between-group differences in the spatial distribution on smaller scales within regions. We found that 48% of the Scandinavian robins, but only 31% of the central European robins, wintered in northern Africa. The remaining parts of both populations wintered in southern and central Europe. Therefore, a substantial part of the Scandinavian population appears to leap over individuals from the central European population during migration. The model is applied to summary tables of numbers of ringed and recovered birds. This allows us to handle very large data sets as, for example, those presented in bird migration atlases.

Journal of Ornithology, 2013

Survival rate is an essential component of population dynamics; therefore, identification of vari... more Survival rate is an essential component of population dynamics; therefore, identification of variation in mortality rates and the factors that influence them might be of key importance in understanding why populations increase or decrease. In Denmark, the Little Owl Athene noctua, a species strongly associated with anthropogenically modified landscapes, is declining fast and may soon face extinction. The population decline is ultimately associated with reduced survival of independent offspring, but reduced survival rates of adults may possibly contribute to the observed decline. To explore the causes of current survival rates, we estimated age-and season-specific survival rates and causes of mortality in Danish Little Owls on the basis of ringed birds 1920-2002, radio tagged adult and juveniles 2005-2008 and nest surveys 2006-2008. We estimate that 32 % of all eggs fledge and survive to 2 weeks post hatching (age of ringing) and 47 % of the nestlings from ringing to fledging. Fifty-five percentage of the radio-tracked fledged young survived to dispersal, i.e. a total survival rate from egg to dispersal of 8 %. Analyses of combined ringing and radio tracking data showed a lower survival rate in the 1st year of life and a much lower rate in the first 3 months of life. Furthermore, the analyses indicated that survival was lower in the winter months for ringing data during 1920-2002 but not for radiotagged owls during 2005-2008 that experienced the highest mortality rates during the breeding season. In radio-tagged adults and fledged juveniles, accidents in buildings and other human infrastructures were responsible for two-thirds of all fatalities. Anthropogenic habitats currently comprise the nesting and roosting habitats for the last Danish Little Owls. The accidental deaths associated with these might to some extent be considered as a contributing factor to the present negative population growth rate of this population.

Journal of Ornithology, 2012

ABSTRACT Migratory birds are frequently found far outside their normal range but the phenomenon i... more ABSTRACT Migratory birds are frequently found far outside their normal range but the phenomenon is poorly understood. We used radio telemetry to track individual migratory flights of several species of songbirds on the Faroe Islands, far west of their normal migration route. Birds with expected easterly and south-easterly migration direction departed westwards out over the Atlantic Ocean, indicating that these birds are actively flying in the “wrong” direction and that their occurrence is not caused by wind drift. This is in contrast to the apparently normal south-westerly to easterly departure directions in birds expected to migrate south or southwest.

Journal of Experimental Biology, 2009

Nowadays few people consider finding their way in unfamiliar areas a problem as a GPS (Global Pos... more Nowadays few people consider finding their way in unfamiliar areas a problem as a GPS (Global Positioning System) combined with some simple map software can easily tell you how to get from A to B. Although this opportunity has only become available during the last decade, recent experiments show that long-distance migrating animals had already solved this problem. Even after displacement over thousands of kilometres to previously unknown areas, experienced but not first time migrant birds quickly adjust their course toward their destination, proving the existence of an experience-based GPS in these birds. Determining latitude is a relatively simple task, even for humans, whereas longitude poses much larger problems. Birds and other animals however have found a way to achieve this, although we do not yet know how. Possible ways of determining longitude includes using celestial cues in combination with an internal clock, geomagnetic cues such as magnetic intensity or perhaps even olfactory cues. Presently, there is not enough evidence to rule out any of these, and years of studying birds in a laboratory setting have yielded partly contradictory results. We suggest that a concerted effort, where the study of animals in a natural setting goes hand-in-hand with lab-based study, may be necessary to fully understand the mechanism underlying the long-distance navigation system of birds. As such, researchers must remain receptive to alternative interpretations and bear in mind that animal navigation may not necessarily be similar to the human system, and that we know from many years of investigation of long-distance navigation in birds that at least some birds do have a GPS -but we are uncertain how it works.

Journal of Experimental Biology, 2007

Songbird movements as an example Imagine tracking the individual movements of red-billed queleas ... more Songbird movements as an example Imagine tracking the individual movements of red-billed queleas (Quelea quelea) across the African continent . Queleas are the world's most abundant birds and have a breeding population in excess of 1.5·billion. Single colonies can contain up to 30·million birds and these large individual colonies can destroy up to 5% of grain crops in the Sahel zone of Africa . Queleas can migrate long distances, sometimes more Tracking animals over large temporal and spatial scales has revealed invaluable and spectacular biological information, particularly when the paths and fates of individuals can be monitored on a global scale. However, only large animals (greater than ~300·g) currently can be followed globally because of power and size constraints on the tracking devices. And yet the vast majority of animals is small. Tracking small animals is important because they are often part of evolutionary and ecological experiments, they provide important ecosystem services and they are of conservation concern or pose harm to human health. Here, we propose a small-animal satellite tracking system that would enable the global monitoring of animals down to the size of the smallest birds, mammals (bats), marine life and eventually large insects. To create the scientific framework necessary for such a global project, we formed the ICARUS initiative (www.IcarusInitiative.org), the International Cooperation for Animal Research Using Space. ICARUS also highlights how small-animal tracking could address some of the 'Grand Challenges in Environmental Sciences' identified by the US National Academy of Sciences, such as the spread of infectious diseases or the relationship between biological diversity and ecosystem functioning. Smallanimal tracking would allow the quantitative assessment of dispersal and migration in natural populations and thus help solve enigmas regarding population dynamics, extinctions and invasions. Experimental biologists may find a global small-animal tracking system helpful in testing, validating and expanding laboratory-derived discoveries in wild, natural populations. We suggest that the relatively modest investment into a global small-animal tracking system will pay off by providing unprecedented insights into both basic and applied nature.

Journal of Experimental Biology, 2009

The identification of the sensory cues and mechanisms by which migratory birds are able to reach ... more The identification of the sensory cues and mechanisms by which migratory birds are able to reach the same breeding and wintering grounds year after year has eluded biologists despite more than 50 years of intensive study. While a number of environmental cues have been proposed to play a role in the navigation of birds, arguments still persist about which cues are essential for the experience based navigation shown by adult migrants. To date, few studies have tested the sensory basis of navigational cues used during actual migration in the wild: mainly laboratory based studies or homing during the non-migratory season have been used to investigate this behaviour. Here we tested the role of olfactory and magnetic cues in the migration of the catbird (Dumetella carolinensis) by radio tracking the migration of birds with sensory manipulations during their actual migratory flights. Our data suggest that adult birds treated with zinc sulphate to produce anosmia were unable to show the same orientation as control adults, and instead reverted to a direction similar to that shown by juveniles making their first migration. The magnetic manipulation had no effect on the orientation of either adults or juveniles. These results allow us to propose that the olfactory sense may play a role in experience based migration in adult catbirds. While the olfactory sense has been shown to play a role in the homing of pigeons and other birds, this is the first time it has been implicated in migratory orientation.

Ringing & Migration, 2009

scientific bird ringing was initiated to study the movements of birds, particularly annual migran... more scientific bird ringing was initiated to study the movements of birds, particularly annual migrants. When a ringed bird is reported to the ringing scheme we have the location of that bird at two points in time -where and when it was ringed and where and when it was found. The collation of reports of ringed birds (recoveries) allows patterns of location change with time to be described. Different methods of presenting these simple data have been devised over the years; initially, the aim was to summarise our knowledge of where birds go. quantitative inference about population behaviour from recovery data is complicated by several factors, particularly the differences in recovery probabilities between different regions. however, the power of ringing-data analysis is now being increased using statistical methods to correct for the expected geographical biases in recovery patterns. The quantitative interpretation of movement patterns of birds is essential for basing conservation policy on sound evidence. The continuation of large-scale ringing and recovery efforts, and the development of statistical tools for analysis and interpretation of the data at continental scales, are therefore vital for the conservation of migratory birds and to understand the impact and spread of disease.

How do geometric constraints influence migration patterns?-Null models exclusively invoking geome... more How do geometric constraints influence migration patterns?-Null models exclusively invoking geometric constraints have recently been demonstrated to provide new insight as to what explains geographic patterns of species richness and range size distribution. Analyses of migration patterns have traditionally been conducted in the absence of appropriate simulations and analytical models. Here we present a null model exclusively invoking geometric constraints and a more advanced analytical model incorporating spread along a migration direction that allow investigation of the influence of physiographical and physiological boundaries for terrestrial taxa, with ocean and sea as geometric constraints, in relation to observed patterns of migration. Our models take into account the low recovery probability of terrestrial taxa over sea. The null model was not found to explain any of the directional variation in the ring-recoveries, but when comparing the distribution of data modeled using a simple clock-and-compass model with distributions of ring-recoveries, geometric constraints were found to explain up to 22% of the variation in ring-recoveries. However, the assumed directional concentrations per step used in the model were much higher than expected, and the qualitative fit of the model was rather poor even when non-terrestrial sites of recoveries were excluded.

Western Phylloscopus bonelli and Eastern Bonelli's Warblers P. orientalis occur as vagrants i... more Western Phylloscopus bonelli and Eastern Bonelli's Warblers P. orientalis occur as vagrants in northwest Europe. Up until 2006, a total of ten Western and five Eastern Bonelli's warblers were recorded in Norway, Sweden and Finland. Only recently have the two taxa attained full species rank, primarily based on differ- ences in DNA, but also in differences in vocalization and minor

A number of possibilities exist for tracking the sometimes even global journeys undertaken by mig... more A number of possibilities exist for tracking the sometimes even global journeys undertaken by migrating birds. Birds fitted with radio transmitters can either be located from the ground or from aircraft (conventional satellite tracking), or from space. Alternatively, positional information obtained by onboard equipment (e.g. GPS units) can be transmitted to receivers in space. Using these tracking methods has provided biologists with a wealth of insight into the migration routes, stopovers and other behaviours in long-distance migrants that are otherwise very difficult to follow. This knowledge has important implicat ions for e.g. conservation and understanding disease transmission and effects of climate chang e. The weight of satellite radio transmitters complicates study of the majority of bird species, but the weight is likely to be greatly reduced in the near future.

... In birds, protandry has been widely reported (Ketterson and Nolan 1976; Myers 1981; Francis a... more ... In birds, protandry has been widely reported (Ketterson and Nolan 1976; Myers 1981; Francis and Cooke 1986; Otahal 1995), and long-term surveys ... Acknowledgments We wish to thank the numerous ringers col-lecting the data, and JM Lausten, P. Lyngs, J. Rabøl as well as ...

With the aim of quantifying spatio-temporal and social factors affecting territorial calls in Lit... more With the aim of quantifying spatio-temporal and social factors affecting territorial calls in Little Owls, we collected data on the calling behaviour of radio tracked individuals from a low-density population in Northern Jutland, Denmark. There was considerable seasonal variation in calling activity. During the breeding season, males calling away from the nest were located in the direction of the neighbouring nesting site, and males with a neighbour within hearing distance called more often than those with a longer distance to the nearest neighbour. Call posts were on average closer to the nest than telemetry observations, but did not appear to be related to mate distance. With a sound pressure level of 82 dB(A) at 1m distance, the territorial calls were estimated to be audible to a distance of 4.4 km. Call posts were on average 4.1 m above the ground, which probably maximizes the transmission distance.

Before dispersal, social and spatial behaviour in owls has only been briefly studied. We used rad... more Before dispersal, social and spatial behaviour in owls has only been briefly studied. We used radio tracking to monitor age-influenced social and spatial behaviour in 10 juvenile Little Owls (Athene noctua) from nests in Northern Jutland, Denmark. On average, the post-fledging dependency period lasted 35 days (n = 6). Juveniles stayed on the natal territory 45 days (n = 5) from independence to dispersal. Half of the juveniles had dispersed by mid-September, and the other half remained on the natal territory until at least mid-October. The home range size (minimum convex polygons) was 0.56 ± 0.53 ha (mean ± SD) from fledging to independence and 3.25 ± 4.15 ha from independence to dispersal. Within the first 40 days after fledging, the nightly distance from the nest and the distance between siblings increased, and the frequency and intensity of begging calls decreased. These results were consistent with the notion that food provided by the parents decreased as juvenile foraging skills increased.

Proceedings of the National Academy of Sciences of the United States of America, 2007

Billions of songbirds migrate several thousand kilometers from breeding to wintering grounds and ... more Billions of songbirds migrate several thousand kilometers from breeding to wintering grounds and are challenged with crossing ecological barriers and facing displacement by winds along the route. A satisfactory explanation of long-distance animal navigation is still lacking, partly because of limitations on field-based study. The navigational tasks faced by adults and juveniles differ fundamentally, because only adults migrate toward wintering grounds known from the previous year. Here, we show by radio tracking from small aircraft that only adult, and not juvenile, long-distance migrating white-crowned sparrows rapidly recognize and correct for a continent-wide displacement of 3,700 km from the west coast of North America to previously unvisited areas on the east coast. These results show that the learned navigational map used by adult long-distance migratory songbirds extends at least on a continental scale. The juveniles with less experience rely on their innate program to find their distant wintering areas and continue to migrate in the innate direction without correcting for displacement.

Ecology and Evolution, 2014

For the study of migratory connectivity, birds have been individually marked by metal rings for m... more For the study of migratory connectivity, birds have been individually marked by metal rings for more than 100 years. The resulting ring recovery data have been compiled in numerous bird migration atlases. However, estimation of what proportion of a particular population is migrating to which region is confounded by spatial heterogeneity in ring recovery probability. We present a product multinomial model that enables quantifying the continent-wide distribution of different bird populations during different seasons based on ring recovery data while accounting for spatial heterogeneity of ring recovery probability. We applied the model to an example data set of the European robin Erithacus rubecula. We assumed that ring recovery probability was equal between different groups of birds and that survival probability was constant. Simulated data indicate that violation of the assumption of constant survival did not affect our estimated bird distribution parameters but biased the estimates for recovery probability. Posterior predictive model checking indicated a good general model fit but also revealed lack of fit for a few groups of birds. This lack of fit may be due to between-group differences in the spatial distribution on smaller scales within regions. We found that 48% of the Scandinavian robins, but only 31% of the central European robins, wintered in northern Africa. The remaining parts of both populations wintered in southern and central Europe. Therefore, a substantial part of the Scandinavian population appears to leap over individuals from the central European population during migration. The model is applied to summary tables of numbers of ringed and recovered birds. This allows us to handle very large data sets as, for example, those presented in bird migration atlases.

Journal of Ornithology, 2013

Survival rate is an essential component of population dynamics; therefore, identification of vari... more Survival rate is an essential component of population dynamics; therefore, identification of variation in mortality rates and the factors that influence them might be of key importance in understanding why populations increase or decrease. In Denmark, the Little Owl Athene noctua, a species strongly associated with anthropogenically modified landscapes, is declining fast and may soon face extinction. The population decline is ultimately associated with reduced survival of independent offspring, but reduced survival rates of adults may possibly contribute to the observed decline. To explore the causes of current survival rates, we estimated age-and season-specific survival rates and causes of mortality in Danish Little Owls on the basis of ringed birds 1920-2002, radio tagged adult and juveniles 2005-2008 and nest surveys 2006-2008. We estimate that 32 % of all eggs fledge and survive to 2 weeks post hatching (age of ringing) and 47 % of the nestlings from ringing to fledging. Fifty-five percentage of the radio-tracked fledged young survived to dispersal, i.e. a total survival rate from egg to dispersal of 8 %. Analyses of combined ringing and radio tracking data showed a lower survival rate in the 1st year of life and a much lower rate in the first 3 months of life. Furthermore, the analyses indicated that survival was lower in the winter months for ringing data during 1920-2002 but not for radiotagged owls during 2005-2008 that experienced the highest mortality rates during the breeding season. In radio-tagged adults and fledged juveniles, accidents in buildings and other human infrastructures were responsible for two-thirds of all fatalities. Anthropogenic habitats currently comprise the nesting and roosting habitats for the last Danish Little Owls. The accidental deaths associated with these might to some extent be considered as a contributing factor to the present negative population growth rate of this population.

Journal of Ornithology, 2012

ABSTRACT Migratory birds are frequently found far outside their normal range but the phenomenon i... more ABSTRACT Migratory birds are frequently found far outside their normal range but the phenomenon is poorly understood. We used radio telemetry to track individual migratory flights of several species of songbirds on the Faroe Islands, far west of their normal migration route. Birds with expected easterly and south-easterly migration direction departed westwards out over the Atlantic Ocean, indicating that these birds are actively flying in the “wrong” direction and that their occurrence is not caused by wind drift. This is in contrast to the apparently normal south-westerly to easterly departure directions in birds expected to migrate south or southwest.

Journal of Experimental Biology, 2009

Nowadays few people consider finding their way in unfamiliar areas a problem as a GPS (Global Pos... more Nowadays few people consider finding their way in unfamiliar areas a problem as a GPS (Global Positioning System) combined with some simple map software can easily tell you how to get from A to B. Although this opportunity has only become available during the last decade, recent experiments show that long-distance migrating animals had already solved this problem. Even after displacement over thousands of kilometres to previously unknown areas, experienced but not first time migrant birds quickly adjust their course toward their destination, proving the existence of an experience-based GPS in these birds. Determining latitude is a relatively simple task, even for humans, whereas longitude poses much larger problems. Birds and other animals however have found a way to achieve this, although we do not yet know how. Possible ways of determining longitude includes using celestial cues in combination with an internal clock, geomagnetic cues such as magnetic intensity or perhaps even olfactory cues. Presently, there is not enough evidence to rule out any of these, and years of studying birds in a laboratory setting have yielded partly contradictory results. We suggest that a concerted effort, where the study of animals in a natural setting goes hand-in-hand with lab-based study, may be necessary to fully understand the mechanism underlying the long-distance navigation system of birds. As such, researchers must remain receptive to alternative interpretations and bear in mind that animal navigation may not necessarily be similar to the human system, and that we know from many years of investigation of long-distance navigation in birds that at least some birds do have a GPS -but we are uncertain how it works.

Journal of Experimental Biology, 2007

Songbird movements as an example Imagine tracking the individual movements of red-billed queleas ... more Songbird movements as an example Imagine tracking the individual movements of red-billed queleas (Quelea quelea) across the African continent . Queleas are the world's most abundant birds and have a breeding population in excess of 1.5·billion. Single colonies can contain up to 30·million birds and these large individual colonies can destroy up to 5% of grain crops in the Sahel zone of Africa . Queleas can migrate long distances, sometimes more Tracking animals over large temporal and spatial scales has revealed invaluable and spectacular biological information, particularly when the paths and fates of individuals can be monitored on a global scale. However, only large animals (greater than ~300·g) currently can be followed globally because of power and size constraints on the tracking devices. And yet the vast majority of animals is small. Tracking small animals is important because they are often part of evolutionary and ecological experiments, they provide important ecosystem services and they are of conservation concern or pose harm to human health. Here, we propose a small-animal satellite tracking system that would enable the global monitoring of animals down to the size of the smallest birds, mammals (bats), marine life and eventually large insects. To create the scientific framework necessary for such a global project, we formed the ICARUS initiative (www.IcarusInitiative.org), the International Cooperation for Animal Research Using Space. ICARUS also highlights how small-animal tracking could address some of the 'Grand Challenges in Environmental Sciences' identified by the US National Academy of Sciences, such as the spread of infectious diseases or the relationship between biological diversity and ecosystem functioning. Smallanimal tracking would allow the quantitative assessment of dispersal and migration in natural populations and thus help solve enigmas regarding population dynamics, extinctions and invasions. Experimental biologists may find a global small-animal tracking system helpful in testing, validating and expanding laboratory-derived discoveries in wild, natural populations. We suggest that the relatively modest investment into a global small-animal tracking system will pay off by providing unprecedented insights into both basic and applied nature.

Journal of Experimental Biology, 2009

The identification of the sensory cues and mechanisms by which migratory birds are able to reach ... more The identification of the sensory cues and mechanisms by which migratory birds are able to reach the same breeding and wintering grounds year after year has eluded biologists despite more than 50 years of intensive study. While a number of environmental cues have been proposed to play a role in the navigation of birds, arguments still persist about which cues are essential for the experience based navigation shown by adult migrants. To date, few studies have tested the sensory basis of navigational cues used during actual migration in the wild: mainly laboratory based studies or homing during the non-migratory season have been used to investigate this behaviour. Here we tested the role of olfactory and magnetic cues in the migration of the catbird (Dumetella carolinensis) by radio tracking the migration of birds with sensory manipulations during their actual migratory flights. Our data suggest that adult birds treated with zinc sulphate to produce anosmia were unable to show the same orientation as control adults, and instead reverted to a direction similar to that shown by juveniles making their first migration. The magnetic manipulation had no effect on the orientation of either adults or juveniles. These results allow us to propose that the olfactory sense may play a role in experience based migration in adult catbirds. While the olfactory sense has been shown to play a role in the homing of pigeons and other birds, this is the first time it has been implicated in migratory orientation.

Ringing & Migration, 2009

scientific bird ringing was initiated to study the movements of birds, particularly annual migran... more scientific bird ringing was initiated to study the movements of birds, particularly annual migrants. When a ringed bird is reported to the ringing scheme we have the location of that bird at two points in time -where and when it was ringed and where and when it was found. The collation of reports of ringed birds (recoveries) allows patterns of location change with time to be described. Different methods of presenting these simple data have been devised over the years; initially, the aim was to summarise our knowledge of where birds go. quantitative inference about population behaviour from recovery data is complicated by several factors, particularly the differences in recovery probabilities between different regions. however, the power of ringing-data analysis is now being increased using statistical methods to correct for the expected geographical biases in recovery patterns. The quantitative interpretation of movement patterns of birds is essential for basing conservation policy on sound evidence. The continuation of large-scale ringing and recovery efforts, and the development of statistical tools for analysis and interpretation of the data at continental scales, are therefore vital for the conservation of migratory birds and to understand the impact and spread of disease.