Insects, mammals and birds are known to use tools, but empirical evidence of the ecological impor... more Insects, mammals and birds are known to use tools, but empirical evidence of the ecological importance of tool-use is scarce. Here, we present the first ecological study of tool-use by a bird species. Woodpecker finches use twigs or cactus spines to pry arthropods out of tree-holes. We compared tool-use during wet and dry seasons in two different vegetation zones: the Arid Zone and the humid Scalesia Zone. In the Scalesia Zone, where food was abundant and easily accessible, woodpecker finches rarely used tools. In contrast, in the Arid Zone, where food was limited and hard to access, they obtained half of their prey using tools during the dry season. Tool-use enabled the birds to reach particularly large and otherwise inaccessible prey hidden in tree-holes. Our data suggest that tool-use in the woodpecker finch has evolved in response to the dry and unpredictable conditions in the coastal zone of the Galápagos Islands.
One of the main functions of exploratory behaviour is to gain information about the environment. ... more One of the main functions of exploratory behaviour is to gain information about the environment. The adaptive value of such behaviour should vary with ecological conditions influencing the diversity and stability of resources, as well as with the costs associated with gathering information. Consequently, predictions can be made about environmental factors influencing the evolution of exploration. We used comparative methods, combining a field experiment with literature data, to study correlated evolution between explorative behaviour and ecology among 13 species of Darwin's finches. Controlling for phylogenetic influences, we found that exploration (measured as the proportion of individuals responding in the experiment) increased with diet diversity and the amount of fruit in diet, consistent with theories stating that exploration aimed at finding new food types should be more beneficial for generalists than for specialists. However, our study is the first to demonstrate a correlation between neophilia and food diversity. Contrary to our prediction, species with a high percentage of concealed food in their diet were less explorative. A possible explanation for this novel finding is that in our study
Renewable Agriculture and Food Systems, Sep 1, 2022
Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However... more Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However, agricultural landscapes are embedded in complex, social-ecological systems and therefore require a strong social-ecological approach for effective conservation measures. The Galapagos Islands are globally recognized for their high levels of biodiversity. Nevertheless, in recent years, Galapagos landbirds have suffered rapid declines, specifically in the agricultural zone. Our study is the first to examine the farmers’ perception of landbirds in the agricultural zone of Santa Cruz, Galapagos Islands. We conducted semi-structured interviews with 38 farmers to characterize the relationship between farmers and landbirds including how landbirds affect farmers and farmers’ perceptions of landbirds. The interviewed farmers managed a diverse array of farm types including coffee in agroforestry settings (23.7%), small-scale fruit and vegetable (60.5%) and livestock production (15.8%). We found that 86.9% of farmers had a positive or neutral perception of birds despite 52.6% of farmers finding finches bothersome. The most common techniques farmers employed to deter birds were putting out food and water, using nets to protect seedbeds and crops and using protective tubes around young plants. Our results suggest a positive potential for future conservation work targeted on farmland biodiversity. Future conservation projects should also address disservices and the mitigation of crop raiding by landbirds, the uninformed use of pesticides and other pest issues such as ants and rats.
The fly, Philornis downsi Dodge & Aitken, was first collected in 1964 on the Galápagos Is... more The fly, Philornis downsi Dodge & Aitken, was first collected in 1964 on the Galápagos Islands and is now widespread across the archipelago. Virtually nothing is known about the behaviour and ecology of the fly as well as for the genus in general. Here, we describe all larval instars for the first time, and discuss infection intensity and impacts of parasitism on nestling survival of Darwin's finches. Adult P. downsi are non-parasitic free-living flies, whereas the larvae are obligate blood-feeding parasites on nestling birds. The larvae show a marked shift in their host site specificity--a novel finding for the genus Philornis: the first and early second larval instars live as agents of myiasis in finch nostrils and other tissues, while the older second and third instar larvae reside in the nest material and feed externally on the blood of nestlings, leading to blood losses in nestlings of 18-55%. Pupation occurs in the bottom layer of the nest. The combined effects of tissue damage by the endoparasitic instar larvae and anaemia by nest-dwelling haematophagous instar larvae account for the high nestling mortality (76%) due to Philornis parasitism. This represents the highest mortality by Philornis reported in the literature and emphasizes the extremely serious threat this parasite poses for the endemic passerine fauna of the Galápagos Islands.
We examined different song parameters leading to a complex song configuration, and song output (p... more We examined different song parameters leading to a complex song configuration, and song output (production), and their relation in male Moustached Warblers and discuss them with reference to female choice. With more than 120 different syllables per two minutes of song, male Moustached Warblers can be regarded as one of the most complex singers within the genus Acrocephalus. We found significant differences between males for almost all song parameters investigated (repertoire size, switching and repetition rate, song speed and strophe length) but not for time spent singing per 20 minutes. This individual variation probably is an important cue for female mate choice. Male Moustached Warblers achieve song complexity mainly via frequent syllable switching. Song complexity seems to be consistent throughout the song and our results suggest that females could assess the overall song complexity of a singer by examining even very short song bouts. Furthermore, a high proportion of motifs-clusters of syllables with the same sequence-occurs within the song of each male which would also facilitate assessment of song complexity by females. However, repertoire size and strophe length were positively related, thus it remains to be investigated which song feature, if any, females actually use.
Social and ecological interactions in the Galapagos Islands, Oct 28, 2017
This chapter discusses the invasion of an avian nest fly, Philornis downsi, to the Galapagos Isla... more This chapter discusses the invasion of an avian nest fly, Philornis downsi, to the Galapagos Islands, its interactions with novel bird hosts, and the strategies that are being implemented to protect threatened, endemic bird species. Philornis downsi was first recorded in the Galapagos less than 60 years ago and is the first bird parasite with parasitic larval stages and non-parasitic adults to reach the islands. Since its introduction, it has successfully spread to most islands and habitats in the archipelago and is associated with a wide range of bird hosts. The consequences of its feeding habits on naive birds have been deleterious to a large number of species, many of which are in decline. An international research group, coordinated by the Charles Darwin Foundation and Galapagos National Park Directorate, is studying various aspects of the biology of P. downsi and its impacts on selected bird species with the aim of fully understanding the complex interactions between flies and birds. The ultimate aim of these investigations is the development of effective management tools.
SummaryThe endemic Galapagos MartinProgne modestais a rare species. Population sizes in the past ... more SummaryThe endemic Galapagos MartinProgne modestais a rare species. Population sizes in the past are unknown, but the few reports available suggest that it has become rarer in some sites. To obtain a better understanding of its population status, a simultaneous survey was conducted in 2017 around the coastline of 14 islands and 23 islets resulting in sightings of only 26 individuals. A simultaneous survey on Sierra Negra volcano on Isabela Island added five more individuals. However, observations from early expeditions and expeditions since 2015 have shown that the volcanoes of Isabela Island are important feeding areas and probable breeding areas for the Galapagos Martin, but these were largely excluded from the survey in 2017 due to logistical reasons. Historical and recent nesting sites include Tagus Cove on Isabela Island and Daphne Major Island. During our 2017 count, three possible new nesting sites were discovered: Daphne Minor, Santiago and a small crater on Punta Cristóbal on southwestern Isabela Island. From 2015 to 2018, 15 nests were also observed on the cliff in Tagus Cove. Two accessible nests were collected and revealed the first records ofPhilornis downsiin Galapagos Martin nests. The impact of parasitism byP. downsiis unknown but potentially severe. Given the lack of general knowledge about the biology of this species and its apparent low population sizes, further studies are urgently needed.
The smooth-billed ani (Crotophaga ani) is a widespread introduced bird species in the biologicall... more The smooth-billed ani (Crotophaga ani) is a widespread introduced bird species in the biologically important archipelago of Galápagos. Many scientists and local people consider it to be a damaging invasive, and it is possible that it impacts native species and ecosystems via multiple mechanisms. However, evidence for this is largely anecdotal and research on smooth-billed anis in Galápagos is limited. Despite this, there have been repeated attempts to control or eradicate the population over the past few decades, all without long-term success. These attempts continue, but no official plan of action regarding this species currently exists. This review brings together all available information on smooth-billed anis in Galápagos. We use both published and unpublished research to answer the following questions: 1. What is known about the history of the smooth-billed anis' introduction to Galápagos? 2. What are the possible impacts of smooth-billed anis in Galápagos? 3. What attempts have been undertaken to control or eradicate smooth-billed anis in Galápagos and what were their outcomes? In answering these questions, we highlight numerous knowledge gaps, in both the current understanding of the impacts of this introduced species and the effectiveness of potential control or eradication methods. We find an urgent need for further research before considered, resourceefficient decisions can be made regarding smooth-billed anis in Galápagos.
The obligate dipterian bird parasite Philornis downsi and the facultative parasitic fly Sarcodexi... more The obligate dipterian bird parasite Philornis downsi and the facultative parasitic fly Sarcodexia lambens were, until recently, unknown on the Galápagos archipelago. The first sign of parasitism of P. downsi on Darwin's finches was found in 1997. Parasitism data were collected from 177 nests of 12 bird species, including eight endemic species. In this study we examined host specificity, infection prevalence (percentage of infested nests), parasite load per nest and per nestling, and breeding success for two climatically different years, 1998 and 2000. We found Philornis downsi in 97% of the investigated nests, Sarcodexia lambens in 32% of the nests and a still unidentified endoparasitic Muscidae in 87% of the clutches investigated. The first two ectoparasites showed no host preference and were found in the dry deciduous coastal zone as well as in the evergreen moist forest. Parasite load per nest varied through the breeding stages, with no parasites during incubation, but with numbers increasing with nestling development. Parasite load per nest showed little variation, but variation in brood size led to different infestation rates per nestling. Small broods suffered higher parasite loads and higher nestling mortality, thus inducing a possible impact on population dynamics.
Toxoplasma gondii is a zoonotic intracellular parasite of particular concern in the conservation ... more Toxoplasma gondii is a zoonotic intracellular parasite of particular concern in the conservation of wildlife due to its ability to infect all homeotherms and potentially cause acute fatal disease in naive species. In the Galapagos (Ecuador), an archipelago composed of more than a hundred islets and islands, the presence of T. gondii can be attributed to human-introduced domestic cats, but little is known about its transmission in wildlife populations. We compared the prevalence of antibodies against T. gondii in sympatric Galapagos wild bird species that differ in diet and contact with oocyst-contaminated soil to determine the relative importance of trophic habits as an exposure factor. Plasma samples were obtained from 163 land birds inhabiting Santa Cruz, one of the cat-inhabited islands, and from 187 seabirds breeding in cat-free surrounding islands (Daphne Major, North Seymour, and South Plaza). These samples were tested for the presence of T. gondii antibodies using the modifie...
Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However... more Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However, agricultural landscapes are embedded in complex, social-ecological systems and therefore require a strong social-ecological approach for effective conservation measures. The Galapagos Islands are globally recognized for their high levels of biodiversity. Nevertheless, in recent years, Galapagos landbirds have suffered rapid declines, specifically in the agricultural zone. Our study is the first to examine the farmers’ perception of landbirds in the agricultural zone of Santa Cruz, Galapagos Islands. We conducted semi-structured interviews with 38 farmers to characterize the relationship between farmers and landbirds including how landbirds affect farmers and farmers’ perceptions of landbirds. The interviewed farmers managed a diverse array of farm types including coffee in agroforestry settings (23.7%), small-scale fruit and vegetable (60.5%) and livestock production (15.8%). We found ...
<jats:p>Emerging pathogens can have devastating effects on naive hosts, but disease outcome... more <jats:p>Emerging pathogens can have devastating effects on naive hosts, but disease outcomes often vary among hosts. Comparing the cellular response of different host species to infection can provide insight into mechanisms of host defense and the basis of host susceptibility to disease. Here, we used RNA-seq to characterize the transcriptomic response of Darwin's finches to avian poxvirus, which is introduced to the Galapagos Islands. We tested whether gene expression differs between infected and uninfected birds, and whether transcriptomic differences were related either to known antiviral mechanisms and/or the co-option of the host cellular environment by the virus. We compared two species, the medium ground finch (Geospiza fortis) and the vegetarian finch (Platyspiza crassirostris), to determine whether related species have similar responses to the same novel pathogen. We found that medium ground finches had a strong transcriptomic response to infection, upregulating genes involved in the innate immune response including interferon production, inflammation, and other immune signaling pathways. In contrast, vegetarian finches had a more limited response to infection. Our results also revealed evidence of viral manipulation of the host's cellular function and metabolism, providing insight into the ways in which poxviruses affect their hosts. Many of the transcriptomic responses to infection mirrored known processes seen in model and in-vitro studies of poxviruses indicating that many pathways of host defense against poxviruses are conserved among vertebrates and present even in hosts without a long evolutionary history with the virus. At the same time, the variation we observed between closely related species indicates that some endemic species of Galapagos finch may be more susceptible to avian pox than others.</jats:p>
Populations of several species of birds endemic to the Galápagos Islands have declined during rec... more Populations of several species of birds endemic to the Galápagos Islands have declined during recent decades, including endemic Little Vermilion Flycatchers (Pyrocephalus nanus). Understanding the reasons for the low breeding success of this species is a prerequisite for developing efficient conservation strategies. Studies of sympatric Darwin's finches suggest two potential reasons: parasitism by the invasive parasitic fly Philornis downsi and extreme climatic events. We investigated the role of each in the breeding success of Little Vermilion Flycatchers during three breeding seasons in the agricultural zone of Isabela Island. We found that Little Vermilion Flycatchers were severely affected by P. downsi, depending on the time of breeding. Nest success was high early in the breeding season (60% were successful) when rates of P. downsi prevalence and intensity were low, but nest success was zero and all nests were infested later in the breeding season. Philornis downsi prevalence and intensity increased with increasing temperature. Both low and high levels of rainfall had a negative effect on nest survival. A parasite removal experiment using insecticide confirmed the detrimental effect of the invasive parasite; nests infested with P. downsi had significantly lower nest success than treated nests. Injection of insecticide into nest bases can be an efficient short-term way to increase the nesting success of Little Vermilion Flycatchers, but finding long-term measures to control the P. downsi population is of utmost importance. La mouche vampire aviaire Philornis downsi menace la moucherolle des Galápagos RÉSUMÉ. Les populations de plusieurs espèces d'oiseaux endémiques des îles Galápagos ont décliné depuis quelques décennies, y compris celle des moucherolles des Galápagos (Pyrocephalus nanus). Il est essentiel de comprendre les raisons du faible taux de reproduction de cette espèce pour développer des stratégies de conservation efficaces. Des études menées sur les pinsons de Darwin sympatriques suggèrent deux raisons possibles : le parasitisme lié à la mouche vampire aviaire Philornis downsi et les événements climatiques extrêmes. Nous avons enquêté sur le rôle de chaque succès de reproduction des moucherolles des Galápagos au cours de trois saisons de reproduction dans la zone agricole de l'île d'Isabela. Nous avons constaté que les moucherolles des Galápagos étaient très affectées par la P. downsi, selon le moment de la période de reproduction. Le succès des nids était élevé au début de la saison de reproduction (60 % d'entre eux réussissaient) lorsque la prévalence et l'intensité des taux de P. downsi étaient faibles, alors que le succès des nids était nul et que tous les nids étaient infestés plus tard au cours de la saison de reproduction. La prévalence et l'intensité des populations de Philornis downsi augmentait avec la hausse des températures. Les niveaux de pluviosité faibles ou élevés entraînaient des effets négatifs sur la survie des nids. Une expérience d'élimination des parasites à l'aide d'insecticide a confirmé les effets délétères des parasites invasifs ; les nids infestés de P. downsi présentaient un taux de succès des nids nettement inférieur par rapport aux nids traités. L'injection d'insecticide dans les bases des nids peut constituer un moyen efficace à court terme pour augmenter le succès de la nidification des moucherolles des Galápagos, mais il est indispensable de trouver des mesures à long terme pour contrôler la population de P. downsi.
On Floreana, the smallest inhabited island in the Gal apagos, populations of several species of b... more On Floreana, the smallest inhabited island in the Gal apagos, populations of several species of birds have either been extirpated or, based on anecdotal evidence and small-scale surveys, are declining. Our objective, therefore, was to conduct a comprehensive survey of landbirds encompassing the entire island during three breeding seasons (2014-2016). We conducted surveys at 59 points in 2014, 257 in 2015, and 295 in 2016. Each survey point was sampled once. We detected 12 species during our surveys. Gal apagos Flycatchers, Yellow Warblers, Small and Medium ground-finches, and Small Tree-Finches were widely distributed over the entire island. Common Cactus-Finches and Medium Tree-Finches had more restricted distributions in the lower or higher parts of the island. Few Dark-billed Cuckoos (Coccyzus melacoryphus), Paint-billed Crakes (Neocrex erythrops), Gal apagos Doves (Zenaida galapagoensis), and Gal apagos Short-eared Owls (Asio flammeus galapagoensis) were recorded. Small Ground-Finches and Small Tree-Finches were found at densities comparable to those on other Gal apagos Islands, whereas densities of Gal apagos Flycatchers and Yellow Warblers were higher on Floreana than on other islands. Endemic Medium Tree-Finches were confined to an area of 24 km², mainly in the highlands, but were still widespread and common in their restricted habitat, with the number of territories estimated to be between 3900 and 4700. Of 22 originally occurring landbirds on Floreana, no fewer than 10 species have either been extirpated or are likely to have been extirpated since the arrival of the first human inhabitants. The combined effects of introduced mammals, large-scale habitat destruction, and direct human persecution were responsible for the extirpation of six species during the 19th century. Three additional species have been extirpated since 1960, likely due to the introduction of the parasitic fly Philornis downsi, and this fly remains a major threat for the remaining bird species. Developing strategies for reducing the impact of these flies on the birds of the Galapagos Islands must be a high priority. In addition, habitat management and restoration, including the control of invasive plants and promotion of native tree species, will be critically important in conserving landbird populations on Floreana.
Insects, mammals and birds are known to use tools, but empirical evidence of the ecological impor... more Insects, mammals and birds are known to use tools, but empirical evidence of the ecological importance of tool-use is scarce. Here, we present the first ecological study of tool-use by a bird species. Woodpecker finches use twigs or cactus spines to pry arthropods out of tree-holes. We compared tool-use during wet and dry seasons in two different vegetation zones: the Arid Zone and the humid Scalesia Zone. In the Scalesia Zone, where food was abundant and easily accessible, woodpecker finches rarely used tools. In contrast, in the Arid Zone, where food was limited and hard to access, they obtained half of their prey using tools during the dry season. Tool-use enabled the birds to reach particularly large and otherwise inaccessible prey hidden in tree-holes. Our data suggest that tool-use in the woodpecker finch has evolved in response to the dry and unpredictable conditions in the coastal zone of the Galápagos Islands.
One of the main functions of exploratory behaviour is to gain information about the environment. ... more One of the main functions of exploratory behaviour is to gain information about the environment. The adaptive value of such behaviour should vary with ecological conditions influencing the diversity and stability of resources, as well as with the costs associated with gathering information. Consequently, predictions can be made about environmental factors influencing the evolution of exploration. We used comparative methods, combining a field experiment with literature data, to study correlated evolution between explorative behaviour and ecology among 13 species of Darwin's finches. Controlling for phylogenetic influences, we found that exploration (measured as the proportion of individuals responding in the experiment) increased with diet diversity and the amount of fruit in diet, consistent with theories stating that exploration aimed at finding new food types should be more beneficial for generalists than for specialists. However, our study is the first to demonstrate a correlation between neophilia and food diversity. Contrary to our prediction, species with a high percentage of concealed food in their diet were less explorative. A possible explanation for this novel finding is that in our study
Renewable Agriculture and Food Systems, Sep 1, 2022
Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However... more Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However, agricultural landscapes are embedded in complex, social-ecological systems and therefore require a strong social-ecological approach for effective conservation measures. The Galapagos Islands are globally recognized for their high levels of biodiversity. Nevertheless, in recent years, Galapagos landbirds have suffered rapid declines, specifically in the agricultural zone. Our study is the first to examine the farmers’ perception of landbirds in the agricultural zone of Santa Cruz, Galapagos Islands. We conducted semi-structured interviews with 38 farmers to characterize the relationship between farmers and landbirds including how landbirds affect farmers and farmers’ perceptions of landbirds. The interviewed farmers managed a diverse array of farm types including coffee in agroforestry settings (23.7%), small-scale fruit and vegetable (60.5%) and livestock production (15.8%). We found that 86.9% of farmers had a positive or neutral perception of birds despite 52.6% of farmers finding finches bothersome. The most common techniques farmers employed to deter birds were putting out food and water, using nets to protect seedbeds and crops and using protective tubes around young plants. Our results suggest a positive potential for future conservation work targeted on farmland biodiversity. Future conservation projects should also address disservices and the mitigation of crop raiding by landbirds, the uninformed use of pesticides and other pest issues such as ants and rats.
The fly, Philornis downsi Dodge &amp; Aitken, was first collected in 1964 on the Galápagos Is... more The fly, Philornis downsi Dodge &amp; Aitken, was first collected in 1964 on the Galápagos Islands and is now widespread across the archipelago. Virtually nothing is known about the behaviour and ecology of the fly as well as for the genus in general. Here, we describe all larval instars for the first time, and discuss infection intensity and impacts of parasitism on nestling survival of Darwin&#39;s finches. Adult P. downsi are non-parasitic free-living flies, whereas the larvae are obligate blood-feeding parasites on nestling birds. The larvae show a marked shift in their host site specificity--a novel finding for the genus Philornis: the first and early second larval instars live as agents of myiasis in finch nostrils and other tissues, while the older second and third instar larvae reside in the nest material and feed externally on the blood of nestlings, leading to blood losses in nestlings of 18-55%. Pupation occurs in the bottom layer of the nest. The combined effects of tissue damage by the endoparasitic instar larvae and anaemia by nest-dwelling haematophagous instar larvae account for the high nestling mortality (76%) due to Philornis parasitism. This represents the highest mortality by Philornis reported in the literature and emphasizes the extremely serious threat this parasite poses for the endemic passerine fauna of the Galápagos Islands.
We examined different song parameters leading to a complex song configuration, and song output (p... more We examined different song parameters leading to a complex song configuration, and song output (production), and their relation in male Moustached Warblers and discuss them with reference to female choice. With more than 120 different syllables per two minutes of song, male Moustached Warblers can be regarded as one of the most complex singers within the genus Acrocephalus. We found significant differences between males for almost all song parameters investigated (repertoire size, switching and repetition rate, song speed and strophe length) but not for time spent singing per 20 minutes. This individual variation probably is an important cue for female mate choice. Male Moustached Warblers achieve song complexity mainly via frequent syllable switching. Song complexity seems to be consistent throughout the song and our results suggest that females could assess the overall song complexity of a singer by examining even very short song bouts. Furthermore, a high proportion of motifs-clusters of syllables with the same sequence-occurs within the song of each male which would also facilitate assessment of song complexity by females. However, repertoire size and strophe length were positively related, thus it remains to be investigated which song feature, if any, females actually use.
Social and ecological interactions in the Galapagos Islands, Oct 28, 2017
This chapter discusses the invasion of an avian nest fly, Philornis downsi, to the Galapagos Isla... more This chapter discusses the invasion of an avian nest fly, Philornis downsi, to the Galapagos Islands, its interactions with novel bird hosts, and the strategies that are being implemented to protect threatened, endemic bird species. Philornis downsi was first recorded in the Galapagos less than 60 years ago and is the first bird parasite with parasitic larval stages and non-parasitic adults to reach the islands. Since its introduction, it has successfully spread to most islands and habitats in the archipelago and is associated with a wide range of bird hosts. The consequences of its feeding habits on naive birds have been deleterious to a large number of species, many of which are in decline. An international research group, coordinated by the Charles Darwin Foundation and Galapagos National Park Directorate, is studying various aspects of the biology of P. downsi and its impacts on selected bird species with the aim of fully understanding the complex interactions between flies and birds. The ultimate aim of these investigations is the development of effective management tools.
SummaryThe endemic Galapagos MartinProgne modestais a rare species. Population sizes in the past ... more SummaryThe endemic Galapagos MartinProgne modestais a rare species. Population sizes in the past are unknown, but the few reports available suggest that it has become rarer in some sites. To obtain a better understanding of its population status, a simultaneous survey was conducted in 2017 around the coastline of 14 islands and 23 islets resulting in sightings of only 26 individuals. A simultaneous survey on Sierra Negra volcano on Isabela Island added five more individuals. However, observations from early expeditions and expeditions since 2015 have shown that the volcanoes of Isabela Island are important feeding areas and probable breeding areas for the Galapagos Martin, but these were largely excluded from the survey in 2017 due to logistical reasons. Historical and recent nesting sites include Tagus Cove on Isabela Island and Daphne Major Island. During our 2017 count, three possible new nesting sites were discovered: Daphne Minor, Santiago and a small crater on Punta Cristóbal on southwestern Isabela Island. From 2015 to 2018, 15 nests were also observed on the cliff in Tagus Cove. Two accessible nests were collected and revealed the first records ofPhilornis downsiin Galapagos Martin nests. The impact of parasitism byP. downsiis unknown but potentially severe. Given the lack of general knowledge about the biology of this species and its apparent low population sizes, further studies are urgently needed.
The smooth-billed ani (Crotophaga ani) is a widespread introduced bird species in the biologicall... more The smooth-billed ani (Crotophaga ani) is a widespread introduced bird species in the biologically important archipelago of Galápagos. Many scientists and local people consider it to be a damaging invasive, and it is possible that it impacts native species and ecosystems via multiple mechanisms. However, evidence for this is largely anecdotal and research on smooth-billed anis in Galápagos is limited. Despite this, there have been repeated attempts to control or eradicate the population over the past few decades, all without long-term success. These attempts continue, but no official plan of action regarding this species currently exists. This review brings together all available information on smooth-billed anis in Galápagos. We use both published and unpublished research to answer the following questions: 1. What is known about the history of the smooth-billed anis' introduction to Galápagos? 2. What are the possible impacts of smooth-billed anis in Galápagos? 3. What attempts have been undertaken to control or eradicate smooth-billed anis in Galápagos and what were their outcomes? In answering these questions, we highlight numerous knowledge gaps, in both the current understanding of the impacts of this introduced species and the effectiveness of potential control or eradication methods. We find an urgent need for further research before considered, resourceefficient decisions can be made regarding smooth-billed anis in Galápagos.
The obligate dipterian bird parasite Philornis downsi and the facultative parasitic fly Sarcodexi... more The obligate dipterian bird parasite Philornis downsi and the facultative parasitic fly Sarcodexia lambens were, until recently, unknown on the Galápagos archipelago. The first sign of parasitism of P. downsi on Darwin's finches was found in 1997. Parasitism data were collected from 177 nests of 12 bird species, including eight endemic species. In this study we examined host specificity, infection prevalence (percentage of infested nests), parasite load per nest and per nestling, and breeding success for two climatically different years, 1998 and 2000. We found Philornis downsi in 97% of the investigated nests, Sarcodexia lambens in 32% of the nests and a still unidentified endoparasitic Muscidae in 87% of the clutches investigated. The first two ectoparasites showed no host preference and were found in the dry deciduous coastal zone as well as in the evergreen moist forest. Parasite load per nest varied through the breeding stages, with no parasites during incubation, but with numbers increasing with nestling development. Parasite load per nest showed little variation, but variation in brood size led to different infestation rates per nestling. Small broods suffered higher parasite loads and higher nestling mortality, thus inducing a possible impact on population dynamics.
Toxoplasma gondii is a zoonotic intracellular parasite of particular concern in the conservation ... more Toxoplasma gondii is a zoonotic intracellular parasite of particular concern in the conservation of wildlife due to its ability to infect all homeotherms and potentially cause acute fatal disease in naive species. In the Galapagos (Ecuador), an archipelago composed of more than a hundred islets and islands, the presence of T. gondii can be attributed to human-introduced domestic cats, but little is known about its transmission in wildlife populations. We compared the prevalence of antibodies against T. gondii in sympatric Galapagos wild bird species that differ in diet and contact with oocyst-contaminated soil to determine the relative importance of trophic habits as an exposure factor. Plasma samples were obtained from 163 land birds inhabiting Santa Cruz, one of the cat-inhabited islands, and from 187 seabirds breeding in cat-free surrounding islands (Daphne Major, North Seymour, and South Plaza). These samples were tested for the presence of T. gondii antibodies using the modifie...
Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However... more Conservation practices in agricultural landscapes can greatly mitigate biodiversity loss. However, agricultural landscapes are embedded in complex, social-ecological systems and therefore require a strong social-ecological approach for effective conservation measures. The Galapagos Islands are globally recognized for their high levels of biodiversity. Nevertheless, in recent years, Galapagos landbirds have suffered rapid declines, specifically in the agricultural zone. Our study is the first to examine the farmers’ perception of landbirds in the agricultural zone of Santa Cruz, Galapagos Islands. We conducted semi-structured interviews with 38 farmers to characterize the relationship between farmers and landbirds including how landbirds affect farmers and farmers’ perceptions of landbirds. The interviewed farmers managed a diverse array of farm types including coffee in agroforestry settings (23.7%), small-scale fruit and vegetable (60.5%) and livestock production (15.8%). We found ...
<jats:p>Emerging pathogens can have devastating effects on naive hosts, but disease outcome... more <jats:p>Emerging pathogens can have devastating effects on naive hosts, but disease outcomes often vary among hosts. Comparing the cellular response of different host species to infection can provide insight into mechanisms of host defense and the basis of host susceptibility to disease. Here, we used RNA-seq to characterize the transcriptomic response of Darwin's finches to avian poxvirus, which is introduced to the Galapagos Islands. We tested whether gene expression differs between infected and uninfected birds, and whether transcriptomic differences were related either to known antiviral mechanisms and/or the co-option of the host cellular environment by the virus. We compared two species, the medium ground finch (Geospiza fortis) and the vegetarian finch (Platyspiza crassirostris), to determine whether related species have similar responses to the same novel pathogen. We found that medium ground finches had a strong transcriptomic response to infection, upregulating genes involved in the innate immune response including interferon production, inflammation, and other immune signaling pathways. In contrast, vegetarian finches had a more limited response to infection. Our results also revealed evidence of viral manipulation of the host's cellular function and metabolism, providing insight into the ways in which poxviruses affect their hosts. Many of the transcriptomic responses to infection mirrored known processes seen in model and in-vitro studies of poxviruses indicating that many pathways of host defense against poxviruses are conserved among vertebrates and present even in hosts without a long evolutionary history with the virus. At the same time, the variation we observed between closely related species indicates that some endemic species of Galapagos finch may be more susceptible to avian pox than others.</jats:p>
Populations of several species of birds endemic to the Galápagos Islands have declined during rec... more Populations of several species of birds endemic to the Galápagos Islands have declined during recent decades, including endemic Little Vermilion Flycatchers (Pyrocephalus nanus). Understanding the reasons for the low breeding success of this species is a prerequisite for developing efficient conservation strategies. Studies of sympatric Darwin's finches suggest two potential reasons: parasitism by the invasive parasitic fly Philornis downsi and extreme climatic events. We investigated the role of each in the breeding success of Little Vermilion Flycatchers during three breeding seasons in the agricultural zone of Isabela Island. We found that Little Vermilion Flycatchers were severely affected by P. downsi, depending on the time of breeding. Nest success was high early in the breeding season (60% were successful) when rates of P. downsi prevalence and intensity were low, but nest success was zero and all nests were infested later in the breeding season. Philornis downsi prevalence and intensity increased with increasing temperature. Both low and high levels of rainfall had a negative effect on nest survival. A parasite removal experiment using insecticide confirmed the detrimental effect of the invasive parasite; nests infested with P. downsi had significantly lower nest success than treated nests. Injection of insecticide into nest bases can be an efficient short-term way to increase the nesting success of Little Vermilion Flycatchers, but finding long-term measures to control the P. downsi population is of utmost importance. La mouche vampire aviaire Philornis downsi menace la moucherolle des Galápagos RÉSUMÉ. Les populations de plusieurs espèces d'oiseaux endémiques des îles Galápagos ont décliné depuis quelques décennies, y compris celle des moucherolles des Galápagos (Pyrocephalus nanus). Il est essentiel de comprendre les raisons du faible taux de reproduction de cette espèce pour développer des stratégies de conservation efficaces. Des études menées sur les pinsons de Darwin sympatriques suggèrent deux raisons possibles : le parasitisme lié à la mouche vampire aviaire Philornis downsi et les événements climatiques extrêmes. Nous avons enquêté sur le rôle de chaque succès de reproduction des moucherolles des Galápagos au cours de trois saisons de reproduction dans la zone agricole de l'île d'Isabela. Nous avons constaté que les moucherolles des Galápagos étaient très affectées par la P. downsi, selon le moment de la période de reproduction. Le succès des nids était élevé au début de la saison de reproduction (60 % d'entre eux réussissaient) lorsque la prévalence et l'intensité des taux de P. downsi étaient faibles, alors que le succès des nids était nul et que tous les nids étaient infestés plus tard au cours de la saison de reproduction. La prévalence et l'intensité des populations de Philornis downsi augmentait avec la hausse des températures. Les niveaux de pluviosité faibles ou élevés entraînaient des effets négatifs sur la survie des nids. Une expérience d'élimination des parasites à l'aide d'insecticide a confirmé les effets délétères des parasites invasifs ; les nids infestés de P. downsi présentaient un taux de succès des nids nettement inférieur par rapport aux nids traités. L'injection d'insecticide dans les bases des nids peut constituer un moyen efficace à court terme pour augmenter le succès de la nidification des moucherolles des Galápagos, mais il est indispensable de trouver des mesures à long terme pour contrôler la population de P. downsi.
On Floreana, the smallest inhabited island in the Gal apagos, populations of several species of b... more On Floreana, the smallest inhabited island in the Gal apagos, populations of several species of birds have either been extirpated or, based on anecdotal evidence and small-scale surveys, are declining. Our objective, therefore, was to conduct a comprehensive survey of landbirds encompassing the entire island during three breeding seasons (2014-2016). We conducted surveys at 59 points in 2014, 257 in 2015, and 295 in 2016. Each survey point was sampled once. We detected 12 species during our surveys. Gal apagos Flycatchers, Yellow Warblers, Small and Medium ground-finches, and Small Tree-Finches were widely distributed over the entire island. Common Cactus-Finches and Medium Tree-Finches had more restricted distributions in the lower or higher parts of the island. Few Dark-billed Cuckoos (Coccyzus melacoryphus), Paint-billed Crakes (Neocrex erythrops), Gal apagos Doves (Zenaida galapagoensis), and Gal apagos Short-eared Owls (Asio flammeus galapagoensis) were recorded. Small Ground-Finches and Small Tree-Finches were found at densities comparable to those on other Gal apagos Islands, whereas densities of Gal apagos Flycatchers and Yellow Warblers were higher on Floreana than on other islands. Endemic Medium Tree-Finches were confined to an area of 24 km², mainly in the highlands, but were still widespread and common in their restricted habitat, with the number of territories estimated to be between 3900 and 4700. Of 22 originally occurring landbirds on Floreana, no fewer than 10 species have either been extirpated or are likely to have been extirpated since the arrival of the first human inhabitants. The combined effects of introduced mammals, large-scale habitat destruction, and direct human persecution were responsible for the extirpation of six species during the 19th century. Three additional species have been extirpated since 1960, likely due to the introduction of the parasitic fly Philornis downsi, and this fly remains a major threat for the remaining bird species. Developing strategies for reducing the impact of these flies on the birds of the Galapagos Islands must be a high priority. In addition, habitat management and restoration, including the control of invasive plants and promotion of native tree species, will be critically important in conserving landbird populations on Floreana.
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