Faith in a bird

Encountering a relatively inconspicuous temperate pine species in the higher reaches of the Indian Western Himalayas, was entirely an outcome of my exploratory trails across the captivating landscape and habitations of Kinnaur in Himachal Pradesh.

Spotting the endemic

While ambling along the streets of a village named Kalpa, I sighted a huddled group of locals, adorned in their customary green velvet caps. They were immersed in deep discussion over the season’s irrigation water distribution logistics across households. This impressive community effort seemed to be governed by an indigenously constituted Gaon Vikas Committee (Village Development Committee) that has been in existence for a very long time. While enquiring if other forms of common property resources were being cooperatively managed in this manner, I stumbled upon a local edible pine nut known as Chilgoza. Chilgoza is collectively extracted from the wild by the native population, for self-consumption and for sale. I found that the pine nut is essentially a seed embedded in the cones of a specific pine tree that these mountain inhabitants referred to as Ree Bothang.

A spell of research engagements revealed that this temperate pine is scientifically known as Pinus gerardiana as a gesture of reverence for the indefatigable spirit of British explorer, Captain Alexander Gerard, who defied perilous topographical barriers to penetrate this secluded region way back in 1817. In his travelogue, Gerard vividly described the landscape to be rugged and mountainous to an extraordinary degree. He was the first to spot this obscure native pine and to introduce it to the formal domains of the botanical world.

I gathered that this was indeed a rare variety of pine. Its sparse and fragmented global distribution across steep xeric terrain of the western Hindu Kush Himalayas was perplexing, stirring me towards some in-depth probing. This initiative yielded striking results. Insights from recent phylogenetic studies attribute the nature of this scant and scattered distribution to unusual tectonic and climatic events during the Cenozoic era. These disrupting forces created constricted isolating environments influencing the evolutionary patterns and the distinctive sporadic occurrence of this temperate species.

This sequence of revelations was really intriguing. I lost no time and set off on reconnaissance surveys across the native habitat of the species. The intensity of cone collection was eye-catching, and I was propelled onto an important ecological concern. If the seeds were being over-extracted to be sold as edible pine nuts, would it not threaten natural regeneration and the sustainability of this range-restricted species? Would local governance mechanisms of resource use mediate any such unsustainable trends?

There I was in an arena that needed me to investigate and weigh the ecological versus livelihood outcomes of natural resource exploitation. Except in this case, conservation concerns appeared to be of prime importance as the temperate pine species under scrutiny was rare.

I felt it was imperative to alert the State Forest Department about my apprehensions and the exigencies of prioritising conservation of an endemic species. I did not hesitate to propose the urgency of a fieldbased research study in the Kinnaur Himalayas for comprehending the gravity of the situation. My genuine concerns did not go unheeded and a study was commissioned by the Department. The interdisciplinary field endeavour, conceived to assess the plight of these forests, focused on unearthing resource-use regimes, livelihood stakes and resource status under changing contextual parameters. The entire expanse of Chilgoza pine habitat between elevations of 2000 and 3000 meters was covered.

Trajectory of resource transitions

Oral history accounts gathered in the field, and archival evidence confirmed that until a few decades ago, the region was quite remote. Therefore, market potential of the pine nut yield remained virtually untapped. As pine nuts were extracted mainly for self-consumption and the population base of the region was insignificant, it may well be presumed that there were hardly any threats to these endemic pine forests in the past. The locals reiterated that it was not unusual to find ripe cones dangling from the branches even after the population’s needs had been fully met.

The speedy development of National Highway-22, for strategic reasons after the 1962 Chinese aggression, dismantled all geographical barriers. A rapid transition towards horticulture followed causing booming local economies and rising incomes.

Better road connectivity and market integration also triggered the sale of pine nuts on an unprecedented scale. The resource started fetching a very high market price as it originates mainly from this restricted geographical domain. Field insights revealed shocking inter-temporal trends. Over the years, the lure of lucrative gains seems to have led to a vicious cycle of destructive and near-total harvesting of pine cones, declining yields, and spiralling prices. With the seeds sold off as pine nuts, one could envisage the insurmountable threats for natural regeneration.

Evidence emanating from the forest surveys corroborated these expected trends. Over-lopped branches due to reckless cone collection were a common sight. As anticipated, the sightings of seedlings and saplings were meagre across most of the forest transects, raising vital concerns about the long-term sustainability of these rare forests. To add to these woes, there has also been a sizeable loss of healthy Chilgoza forests to a series of hydropower projects and haphazard road alignments.

Neither the local community nor the State appeared to have confronted the negative ecological implications of resource extraction. The endemic nature of this species was not even common knowledge.

I discovered that the emerging scientific evidence on the vulnerability of the Himalayas to climate change predict primary extinction threats for range-restricted species such as Chilgoza pine. Under such impending circumstances these tree line forests would have nowhere to seek refuge.

Assuaging discovery As natural regeneration had bothered me right from the inception of this study, I was hell-bent on photodocumenting every Chilgoza seedling and sapling encountered in the forest plots. These images exposed some unusual trends. Healthy regeneration was evident below rocks and I wondered how the seeds came to be dispersed in such odd locations. In some of these areas, clustered seedling growth was also visible. Meanwhile, stray local insights on the common crow’s affinity to hoard pine seeds belowground kept baffling me intermittently.

Although my research journey so far seemed to be ending on a dismal note, an accidental discovery provided some room for solace. Thanks to my ordinary “point and shoot” camera, I seem to have inadvertently spotted an avian wonder which is capable of fostering natural regeneration for pines like Chilgoza. Such are the rewards of sauntering in the wilderness. It turns out that I was the first to have made this discovery along these Western Himalayan forest tracts! In what follows I elaborate on my path to the discovery.

While trailing behind my field team, I sensed a lot of bird activity in one of the Chilgoza pine forests we were passing. At first I thought the resonating sounds were those of a persevering woodpecker. When I finally spotted a bird precariously perched like a weather cock atop a mature cone dangling from the branch of a Chilgoza tree. I managed to capture it on my camera. It turned out to be the large-spotted nutcracker (Nucifraga multipunctata) of the corvid family, which is endemic to the Western Himalayas. Nutcrackers are a small genus of 2-3 species closely associated with montane coniferous forests across parts of North America, Europe and Asia. They are specialised feeders on pine seeds which forms a large fraction of their diet.

But what was the explanation for the cropping up of seedlings in the most unusual locations? Did it have anything to do with the common crow concealing seeds that my local respondents were trying to convey? I did not seem to have a definitive answer. But I had no idea that I was on the verge of unearthing one of the most fascinating biological interactions. While trying to make some sense of my inexplicable field observations, I chanced upon Hutchins and Lanner’s research work as well as Diana Tomback’s invigorating research findings on the role of avian seed dispersal for pines that have wingless seeds. The wingless feature of Chilgoza pine seeds was a vital clue for unravelling the mystery I could not solve. It appears that 20 out of a 100 odd species of pine belonging to the genus Pinus, have wingless seeds that cannot be scattered by wind. 19 of these, including the Chilgoza pine, fall under the subgenus Strobus, which are known to be dispersed by corvids, especially nutcrackers. There is established evidence on this nature of avian seed dispersal in the case of eight of these Strobus pines. It is presumed to be the same for the remaining species as well.

This bird-pine relationship is a classic instance of obligate mutualism, wherein neither species can survive without the other. This coexistence is crucial and mutually beneficial. While the pine is virtually dependent on its avian seed disperser for regeneration, the nutcracker is heavily dependent on the pine for its primary year-round food source.

Studies pertaining to the Western temperate belts have established that these nutcrackers have excellent spatial memory. They harvest tens of thousands of pine seeds and bury them in small caches for later retrieval during winter, spring and parts of the following summer. Their caches function as seed dispersal, as seeds that are not retrieved germinate in favourable years and congenial microsites. These fascinating insights were enough to deduce that the cropping up of single or multi-stem juvenile pines in the most unusual locations that I had repeatedly spotted could well be untapped nutcracker caches.

Morphological traits of both species have ingeniously evolved over time to facilitate this specialized interaction. The nutcracker has a sturdy pointed bill to break open cones easily and a well-developed pouch below the tongue to transport nearly 80-90 seeds at a time, to its caching sites. Bird-dispersed pines have special features which assist nutcracker foraging. For instance, seeds are wingless and heavy. Ripe seeds are retained in cones either by indehiscence or restraining flanges after cones dehisce. These traits prevent loss of seeds due to wind dispersal or passive seed dispersal. Nutcrackers cache in a variety of different topographical sites and away at long distances, sometimes causing seedling growth in clusters and a genetic population structure that is quite distinct from wind dispersed pines.

Scientific evidence has established that nutcrackers are primary seed disperses for pines that have wingless seeds. Some other vertebrates may occasionally be effective as dispersers but rarely establishers. Only the nutcracker performs both roles.

This is because nutcrackers scatter-hoard well beyond their metabolic needs, at depths to reduce predation and desiccation and in sites favourable for growth making them potential dispersers capable of regenerating these Strobus pine forests.

Based on these scientific insights and my supportive field evidence, there is a high chance that bird-pine mutualism in Chilgoza pine forests does exist. A recent study undertaken to confirm the genetic diversity in Chilgoza forests found high rates of cross-pollination pointing towards substantial chances of pollen and seed migration from one site to another. The researchers did not provide any explanation for these trends. But this finding could well be attributed to the nutcrackers scatter hoarding of seeds across the landscape. This possibility is substantiated by recent research evidence from North America, where ringed nutcrackers were found to disperse seeds up to 32 kilometers¸ moving seeds longer distances than wind, rodents and every other seed-hoarding bird. These results consistently reinforce the feasibility of active nutcracker-pine interaction in Kinnaur. In this eventuality, the ruthless nature of seed extraction unravelled in this study could jeopardize the survival of the nutcracker and the pivotal role it may be playing in re-wilding the degrading landscape.

The poor status of Chilgoza pine forests calls for immediate attention to prevent the endemic species from aging away, besides mitigating threats to the fragile mountain ecosystem it may be judiciously harbouring. As artificial propagation strategies have not produced the expected results and a concerted conservation drive is still warranted, managing forests to enhance nutcracker visitation can be a cost-effective strategy for restoring the depleting forest stock. To achieve this end, locals could be incentivised to leave a few cones behind on every tree. It is also important to curtail cone collection altogether on a rotational basis from a few areas to facilitate recovery and regeneration. A similar approach could be initiated to restrict grazing so that seedlings and saplings are not susceptible to browsing or trampling.

This article is from issue


2020 Sep