Calling on the wolf4 min read . Updated: 10 Mar 2017, 07:09 PM IST
While the Himalayan wolves have the most distinct howl acoustic structure, the Indian wolf has the highest mean frequency
It was October 2014. Winter had descended on Ladakh—a cold and barren mountain terrain where the air is rarefied and the wind wild.
On a freezing morning in this inhospitable desert, a young American wildlife biologist, Lauren Hennelly, managed to get close to her research subject: the Himalayan wolf. “Since (these) wolves are rare and few researchers have even seen one here, I was worried that I was not going to end up with any sightings. Before arriving in India, I had previously studied mostly birds and bats; I had never conducted fieldwork on a large carnivore. Additionally, this study was challenging since I had to first find the wolves and then get close for recording and playing (their) calls," she says. Hennelly had arrived in July 2014 on a Fulbright-Nehru programme, in collaboration with the Dehradun-based Wildlife Institute of India (WII). She started her research work in September that year, and carried on till May 2015.
“Fieldwork was tough in the Transhimalaya. It was very cold and we had to camp in the open. We just sat outside for multiple days and waited for wolves. I remember waking up before the sun came out with the camp water all frozen, and cradling my teacup in my hands to warm them up," recounts Hennelly, the lead author of the study.
For days, Hennelly and her colleagues had been on the look-out in Changthang, a high-altitude plateau in Ladakh, for wolves, one of the most enigmatic large carnivores inhabiting this wind-chiselled landscape. Finally, in the vicinity of TsoKar, a high-altitude glacial lake, the team managed to record, for the first time, the howling of a pack of Himalayan wolves.
Hennelly had flown half-way around the globe to hear this sound for her interest lay in the acoustic structure of wolf howls.
Why? According to Hennelly and other wolf biologists, the howl is the main long-distance vocalization for social interaction and communication amongst wolves. Variations in wolf howl acoustic structure may give us insights into the evolutionary history, morphology and ecology of a population or subspecies. Moreover, individual wolves can be identified by their howls, like tigers can be identified by their unique stripe pattern.
The WII has also been working on Project Wolf, using howl surveys as a method to gain information on packs and estimate populations. There is a wide range of vocal variations across mammalian species such as seals, whales, rodents, primates and bats. Yet this area remains relatively unexplored for most mammal groups.
“Very little is known about the wolves of Transhimalaya and, generally, the wolves of India (the Himalayan wolf and Indian wolf)," says Hennelly. The Himalayas harbour one of the oldest and most mysterious wolf lineages, thought to have remained isolated for 800,000 years. Similarly, the Indian wolf lineage is said to be anywhere between 270,000-400,000 years old. “Due to their elusiveness and the challenge of conducting fieldwork in this region, research on these wolves is rare, and genetic samples scarce.
“The Himalayan and Indian wolf have a unique ancestry but very little is known about their ecology, distribution and behaviour, leading to confusion in taxonomic status. The taxonomic status of the Himalayan wolf is still debated and some scientists consider it to be a separate wolf species," says Hennelly, adding that this study was an opportunity to record the howls of Himalayan and Indian wolves in the hope of understanding the possible differences among India’s genetically distinct wolf lineages.
Not only is there uncertainty about their evolutionary significance, little is known about the current population trends and distribution of Himalayan and Indian wolves. Some of this uncertainty is because there is little understanding of how wolves from different regions of Asia are related to each other.
Understanding the distribution of these different types of wolves can help conservationists develop effective conservation programmes.
Equipped with a microphone, digital recorder and speaker for playing back recorded howls, Hennelly tracked wolves during their peak daily howling periods, morning and evening. “I recorded Himalayan wolves from Ladakh and Spiti. For Indian wolves, I recorded four packs in Maharashtra. I also visited zoos in Darjeeling, Gangtok, Nainital, Delhi and Pune to record captive Himalayan and Indian wolves," she says.
The survey-and-recording trip ended with a total of 418 wolf howls—301 howls of Himalayan wolves and 117 howls of Indian wolves. Additionally, she had 652 recordings from eight species across the globe.
“This was a pretty laborious process since there were 1,070 howls to go through! Each howl had to be analysed by gathering information on frequencies, using software specifically designed for studying animal vocalization. We had to obtain many different measurements to describe a wolf howl, such as peak frequency, average frequency, and duration of howl. Additionally, our team consisted of researchers from the US, India, Italy, Spain and England; we worked together on building a database with howls from many different wolf subspecies to compare with the Himalayan and Indian wolf howls," says Hennelly.
The study, Howl Variation Across Himalayan, North African, Indian And Holarctic Wolf Clades: Tracing Divergence In The World’s Oldest Wolf Lineages Using Acoustics, published in Current Zoology, illustrates that the long-range vocalization of the wolf shows distinct acoustic differences among subspecies. While the Himalayan wolves (and North African wolves) have the most distinct acoustic structure, the Indian wolf has the highest mean frequency. According to the group of five wildlife biologists who collaborated on this project, “understanding these acoustic differences contributes to a comprehensive view of the genetic, behavioural and ecological attributes of a species and aids in the taxonomic recognition of cryptic species."
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