Description of Published Research
Elevational migration patterns and hypoxia physiology influence avian malaria prevalence and intensity in the Himalayas.
Himalayan birds show two kinds of elevational movement strategies. Some are year-round high-elevation residents while others are seasonal migrants. Farah Ishtiaq and I tested for the effect of elevational movement strategy on the prevalence and intensity of avian blood parasite infections in Himalayan birds. We further tested how these infections affected the hemoglobin concentration, a critical oxygen transport mechanism, of birds. We found that elevational migrants transport avian hemo-parasite infections from low to high elevations through their elevational movements. Furthermore, hemoglobin concentration was suppressed in high elevation resident but not elevational migrant birds during high intensity infections, suggesting that high-elevation residents might be more at risk due to avian malaria than elevational migrants that have been exposed to these infections for centuries. Check out this cool paper here!
Himalayan birds show two kinds of elevational movement strategies. Some are year-round high-elevation residents while others are seasonal migrants. Farah Ishtiaq and I tested for the effect of elevational movement strategy on the prevalence and intensity of avian blood parasite infections in Himalayan birds. We further tested how these infections affected the hemoglobin concentration, a critical oxygen transport mechanism, of birds. We found that elevational migrants transport avian hemo-parasite infections from low to high elevations through their elevational movements. Furthermore, hemoglobin concentration was suppressed in high elevation resident but not elevational migrant birds during high intensity infections, suggesting that high-elevation residents might be more at risk due to avian malaria than elevational migrants that have been exposed to these infections for centuries. Check out this cool paper here!
Breast-stripe Dimorphism and beak eco-morphology in Green-backed Tits (Parus monticolus)
A bird’s plumage serves many purposes. It keeps the bird warm on cold days, is used in species identification and recognition, and often serves as a signal of a male bird’s health and quality. Breast stripes in the great tit (Parus major) have been extensively studied and linked to a variety of functions from male quality to social dominance and higher fitness. Green-backed tits (Parus monticolus) also have a large vertical breast stripe. Males have a thick black breast stripe while females have a thin ashy stripe (See Figure, males top panel, females bottom panel). We quantified this trait in a Himalayan population of green-backed tits to show that males do in fact have a much bigger and broader breast stripe, a trait that can be used to sex the otherwise monomorphic bird in field. We also compared beak morphology of male and female green-backed tits among the sexes and within the sexes across seasons. We found that not only are male beaks differently shaped than female beaks, they also grow shorter in the breeding season when they are likely doing a lot of courtship feeding while the female incubates the eggs! Check it out here!
A bird’s plumage serves many purposes. It keeps the bird warm on cold days, is used in species identification and recognition, and often serves as a signal of a male bird’s health and quality. Breast stripes in the great tit (Parus major) have been extensively studied and linked to a variety of functions from male quality to social dominance and higher fitness. Green-backed tits (Parus monticolus) also have a large vertical breast stripe. Males have a thick black breast stripe while females have a thin ashy stripe (See Figure, males top panel, females bottom panel). We quantified this trait in a Himalayan population of green-backed tits to show that males do in fact have a much bigger and broader breast stripe, a trait that can be used to sex the otherwise monomorphic bird in field. We also compared beak morphology of male and female green-backed tits among the sexes and within the sexes across seasons. We found that not only are male beaks differently shaped than female beaks, they also grow shorter in the breeding season when they are likely doing a lot of courtship feeding while the female incubates the eggs! Check it out here!
Avian Vocal Mimicry in Tawny Larks (Galerida deva)
The Sykes’s (Tawny) lark (Galerida deva) is a little-known endemic of the Indian subcontinent. The famous Indian ornithologist Salim Ali describes it as a remarkable vocal mimic, yet the extent and diversity of its mimicry has not been described in detail. Taylor Crisologo, a Cornell undergrad interested in avian vocal mimicry; Viral Joshi, a bird recordist from Gujarat, India and I published a paper where we describe the incredible variety of birds the Sykes’s larks mimic in Viral’s native Amareli in Gujarat. Using acoustic analysis, we also measured how accurate the larks were at mimicking species they regularly mimicked. Among the calls we analyzed, Sykes’s larks mimicked 34 species of birds. While they mimic some birds very accurately, the figure shows the spectogram of a common babbler and its mimicry by the lark below, other species mimicry by larks is easily distinguishable in structure with acoustic analysis. This study will hopefully lead to more studies on the function of mimicry in this species.
The Sykes’s (Tawny) lark (Galerida deva) is a little-known endemic of the Indian subcontinent. The famous Indian ornithologist Salim Ali describes it as a remarkable vocal mimic, yet the extent and diversity of its mimicry has not been described in detail. Taylor Crisologo, a Cornell undergrad interested in avian vocal mimicry; Viral Joshi, a bird recordist from Gujarat, India and I published a paper where we describe the incredible variety of birds the Sykes’s larks mimic in Viral’s native Amareli in Gujarat. Using acoustic analysis, we also measured how accurate the larks were at mimicking species they regularly mimicked. Among the calls we analyzed, Sykes’s larks mimicked 34 species of birds. While they mimic some birds very accurately, the figure shows the spectogram of a common babbler and its mimicry by the lark below, other species mimicry by larks is easily distinguishable in structure with acoustic analysis. This study will hopefully lead to more studies on the function of mimicry in this species.
Significant range-overestimation for Western Ghats endemic birds
The total range size of a bird species is an important determinant of its probability of extinction according to the IUCN. In a recently published paper, we showed that species distribution models for 18 Western Ghats endemic birds predict that these species are found in a much smaller subset of their distributional range. This has significant implications for their IUCN threat categorizations. Check it out here!
The total range size of a bird species is an important determinant of its probability of extinction according to the IUCN. In a recently published paper, we showed that species distribution models for 18 Western Ghats endemic birds predict that these species are found in a much smaller subset of their distributional range. This has significant implications for their IUCN threat categorizations. Check it out here!
Interspecific competition among Himalayan titmice?
Elevational species replacement is a widespread pattern among montane birds. Interspecific competition is considered an important driver of elevational distribution on tropical mountains but its importance in temperate systems has not been widely tested. We studied whether interspecific competition drives the distribution of two Himalayan birds the cinereous tit and the green-backed tit. We carried out behavioral experiments to study competition over space (playbacks) and competition over food (feeder trials). We show that although green-backed tits are behaviorally dominant over cinereous tits, habitat might be more important in driving the distribution of these two species. This study was recently accepted for publication in the Journal of Avian Biology.
Check out this video of green-backed tits dominating over cinereous tits in our feeder experiment!
Photo credits: Shailee Shah, Soham Dixit and HBW
Elevational species replacement is a widespread pattern among montane birds. Interspecific competition is considered an important driver of elevational distribution on tropical mountains but its importance in temperate systems has not been widely tested. We studied whether interspecific competition drives the distribution of two Himalayan birds the cinereous tit and the green-backed tit. We carried out behavioral experiments to study competition over space (playbacks) and competition over food (feeder trials). We show that although green-backed tits are behaviorally dominant over cinereous tits, habitat might be more important in driving the distribution of these two species. This study was recently accepted for publication in the Journal of Avian Biology.
Check out this video of green-backed tits dominating over cinereous tits in our feeder experiment!
Photo credits: Shailee Shah, Soham Dixit and HBW
Life-history characteristics influence physiological strategies to cope with hypoxia in Himalayan birds
Hypobaric hypoxia represents an important physiological stressor for montane organisms. We demonstrate that physiological strategies to cope with hypoxia vary among birds with the duration of time species spend in hypoxic conditions annually. Taking a novel comparative physiology approach we studied variation in haemoglobin concentration across nine elevational migrants, which live at high-elevations for only 4-6 months/year, and six year-round high-elevation resident birds across a 2200m Himalayan elevational gradient. We show that elevational migrants increase blood haemoglobin concentration by increasing haematocrit (red-cell volume) which is significantly different from high-elevation residents which increase mean cellular haemoglobin concentration to cope with hypoxia. Read it here
Hypobaric hypoxia represents an important physiological stressor for montane organisms. We demonstrate that physiological strategies to cope with hypoxia vary among birds with the duration of time species spend in hypoxic conditions annually. Taking a novel comparative physiology approach we studied variation in haemoglobin concentration across nine elevational migrants, which live at high-elevations for only 4-6 months/year, and six year-round high-elevation resident birds across a 2200m Himalayan elevational gradient. We show that elevational migrants increase blood haemoglobin concentration by increasing haematocrit (red-cell volume) which is significantly different from high-elevation residents which increase mean cellular haemoglobin concentration to cope with hypoxia. Read it here
A Comprehensive Bird Checklist From Our Field-site (Chopta-Mandal)
Two technicians Soham Dixit and Viral Joshi who worked with me during my 2015 field season and I just published a paper on the elevational distribution of birds in my study site in the western Himalayas. Check out the paper here. I feel its extremely important to document and publish natural history as it can serve as a baseline for future studies and work toward filling the so-called “Wallacean short-fall”. Last year, Andre Dhondt (my PhD advisor) and I published the first description of a nest of yellow-browed tit (Sylviparus modestus) from India. It’s the western-most and elevationally highest nest described so far.
Two technicians Soham Dixit and Viral Joshi who worked with me during my 2015 field season and I just published a paper on the elevational distribution of birds in my study site in the western Himalayas. Check out the paper here. I feel its extremely important to document and publish natural history as it can serve as a baseline for future studies and work toward filling the so-called “Wallacean short-fall”. Last year, Andre Dhondt (my PhD advisor) and I published the first description of a nest of yellow-browed tit (Sylviparus modestus) from India. It’s the western-most and elevationally highest nest described so far.
Fruiting Season Length Drives Global Distribution of Female Only Care in Frugivorous Passerines
Contingas, manikins and birds of paradise are some of the best examples of how elaborate, ornate and crazy male bird plumage can get. These birds also have some thing else in common. They are all frugivores and have female-only parental care where the male’s only role in reproduction is mating with the female. The female then goes on to build the nest and raise chicks all by herself. Due to several other reasons, all tropical birds have small clutch sizes and frugivores more so, often having a brood of one or two eggs. Frank La Sorte and I predicted that if the female has to do it all alone, then such a feat is only possible in areas where the fruiting seasons are really long so females can have abundant food resources for lengthy periods of time in which she can raise multiple small broods. We did a global analysis involving all frugivorous passerines and show that female-only care birds are concentrated in areas with the longest fruiting seasons in the equatorial tropics. Frugivores away from the equator are more likely to be species showing bi-parental care and probably with males that aren’t as flashy as birds of paradise.
Contingas, manikins and birds of paradise are some of the best examples of how elaborate, ornate and crazy male bird plumage can get. These birds also have some thing else in common. They are all frugivores and have female-only parental care where the male’s only role in reproduction is mating with the female. The female then goes on to build the nest and raise chicks all by herself. Due to several other reasons, all tropical birds have small clutch sizes and frugivores more so, often having a brood of one or two eggs. Frank La Sorte and I predicted that if the female has to do it all alone, then such a feat is only possible in areas where the fruiting seasons are really long so females can have abundant food resources for lengthy periods of time in which she can raise multiple small broods. We did a global analysis involving all frugivorous passerines and show that female-only care birds are concentrated in areas with the longest fruiting seasons in the equatorial tropics. Frugivores away from the equator are more likely to be species showing bi-parental care and probably with males that aren’t as flashy as birds of paradise.
Cavity nesting affects the life history evolution of Old World Flycatchers.
Nick Mason and I tested some long standing predictions of the effect of cavity nesting on the life history of birds, in a comparative phylogenetic framework. We chose the Muscicapidae or Old World Flycatchers as our candidate group because of a good dispersion of cavity-nesting and open-nesting traits across species. We discovered that cavity nesting has evolved multiple times independently in this group. We show that interspecific competition has had a strong impact on which species are cavity nesting. We also show that migratory behavior is much more common in cavity nesting lineages than open nesting lineages and hence cavity nesting has been crucial for the evolution of migratory behavior in Old World Flycatchers.
Read the paper here and coverage about it here. The figure shows the most comprehensive phylogeny of muscicapidae till date.
Nick Mason and I tested some long standing predictions of the effect of cavity nesting on the life history of birds, in a comparative phylogenetic framework. We chose the Muscicapidae or Old World Flycatchers as our candidate group because of a good dispersion of cavity-nesting and open-nesting traits across species. We discovered that cavity nesting has evolved multiple times independently in this group. We show that interspecific competition has had a strong impact on which species are cavity nesting. We also show that migratory behavior is much more common in cavity nesting lineages than open nesting lineages and hence cavity nesting has been crucial for the evolution of migratory behavior in Old World Flycatchers.
Read the paper here and coverage about it here. The figure shows the most comprehensive phylogeny of muscicapidae till date.
Morphometry of Himalayan birds
Over the past 3 years, I have been collecting detailed morphological and natural history data on west Himlayan birds through mist netting across a 2500m elevational gradient. I have data on beak, wing, tarsus, mass, breeding status and other ecological variables for more than 1500 individual birds of more than 100 species. Write to me if you would like to request any data. The data is a result of a lot of hard-work and I would expect a formal collaboration before I can share data.
Over the past 3 years, I have been collecting detailed morphological and natural history data on west Himlayan birds through mist netting across a 2500m elevational gradient. I have data on beak, wing, tarsus, mass, breeding status and other ecological variables for more than 1500 individual birds of more than 100 species. Write to me if you would like to request any data. The data is a result of a lot of hard-work and I would expect a formal collaboration before I can share data.
Connectivity within sky-island bird populations.
For two months before joining grad school, I worked as a research fellow for the National Centre for Biological Sciences in the unique Western Ghats "sky-island" habitats. Working with Robin Vijayan's skilled field assistants, we travelled across sky-islands mist netting highly range restricted and endemic birds. This was quite a unique experience for me as I was mist-netting for the first time in my life, with assistants (or rather any local) with whom I didn't share a common language, in some of the most breath- taking landscapes I have been in, which have some REALLY cool animals and plants. Every time I was frustrated with the language barrier, we caught something cool like a Crested Goshawk or saw something cool like a Nilgiri Marten, making it all worth while (Read about my experiences).
King cobra Telemetry Project (KCTP)
For eight months I worked at the Agumbe Rainforest Research Station as a project supervisor on the KCTP. It was an amazing experience to live at a field station in the rainforest, wake up to the song of the Malabar Whistling Thrush, track king cobras, observe birds, talk to eco-tourists about rainforest conservation, it was all in a day's work there. I also analyzed some of the data previously collected by the project and we published a paper on the effects of translocation on the ranging patterns and behavior of the king cobra. However, in this paper we are also addressing the larger issue of rampant snake translocation all across India and its probable effects on translocated snakes.
Kaziranga Corridor Monitoring Program
After finishing my Master's degree, in early 2010, Aaranyak hired me as a technician to design a corridor monitoring protocol for large mammals in the Kaziranga National Park-Karbi Anglong Wildlife Sanctuary landscape, a world heritage site in north-east India. This beautiful floodplain has one of the highest densities of tigers along with about 2000 rhinos, elephants and wild water buffaloes making it an exhilarating place to work. However, the fringes of the park also have a burgeoning human population making the conservation of this landscape challenging. We developed a unique method to monitor the three corridors that connect the Kaziranga floodplain with the Karbi Anglong hills using track-plots and measuring the frequency of tracks to arrive at a corridor use index. The Aaranyak team has been regularly monitoring the corridor using this method for the past three years.
The Wildlife Institute of India and research on birds in Teak (Tectona grandis) plantations.
My Master's at the Wildlife Institute of India was a highly enriching experience. Apart from taking a many courses ecology, this course also gave me the opportunity to conceive, plan and execute an independent research project. For my Master's Dissertation, I researched the bird communities in two age classes of teak and compered them to the surrounding natural forests. I discovered that teak plantations vary significantly across seasons in th number of species they support. This research also resulted in the range extension of the Sri Lanka Frogmouth, a cryptic nocturnal bird and the first detailed description of the avifauna of this region.
Food habits of the Indian Fox (Vulpes benghalensis)
In the summer of 2007, SPROUTS Mumbai and Tiger Watch Ranthambore, gave me the opportunity to do my first field research! I observed the den site behavior of a family of 3 adult and 4 juvenile foxes on the outskirts of the Ranthambore Tiger Reserve in Rajasthan, India. I also analyzed fox scat samples and discovered that the main prey for the foxes was the abundant termites that made extensive tunnels just under the soil surface. Other highlights of the trip included about 150 species of birds and the opportune sighting of a couple of Honey Badgers on a night walk. My observations and experiences were published in the magazine of the Bombay Natural History Society, Hornbill. This experience hooked me to, what I feel, is a life of field research. The Fox, Outfoxed!
