Skulker

As many of you will know, I am a trainee bird ringer and have been since 2014. Involved in the complicated process is putting a small, lightweight ring on the leg of a bird, on which is inscribed a unique number. This enables individual birds to be recognised if they are later recaught or found dead, allowing ornithologists to learn more about their migration and biology.

In my four years of being a ringer, I’ve had the chance to ring a wide variety of bird species, ranging from over 100 Blue Tits to some scarcities including Yellow Wagtail, Redstart, Wheatear and Wood Warbler and larger birds such as Stock Dove and Woodpigeon. However, last Sunday’s ringing experience will probably go down as one of my favourites so far.

Fellow Sussex young birder Mya Bambrick and I arrived at Knepp Estate, south-west of Horsham, at 6am. There we met my trainer Tony Davis who had already set up four mist-nets around a field consisting of mainly bramble and willow scrub. This is a fantastic habitat for migrating birds as well as several scarce breeders due to the amount of cover the scrub produces and the blackberries which ripen at exactly the right time to fuel many migratory passerines on their southward journeys. The mist-nests are ideal for catching birds as they are fine enough to be invisible to birds flying between bushes, which fly into the net and fall into a pocket from which they are extracted by licensed ringers.

It was on the first net-round when I noticed that there was something slightly different in the bottom pocket of one of the mist-nets. It didn’t take long for me to realise that it was a Grasshopper Warbler. Grasshopper Warblers, so-called due to their bizarre song which resembles that of a stridulating grasshopper, is a localised breeding species found mainly in fens and coarse grassland and is not often found in high density. However, while researching for this blog post, it was good to learn that they are showing a positive population trend with the UK population experiencing a 23% increase in numbers in the 14 years between 1995 and 2009. This is thought to be as a result of improved survival rates in the wintering grounds of west Africa. Particular preference is shown by British Grasshopper Warblers towards Senegal and The Gambia, which we have learnt from recoveries of ringed birds in those countries. However despite this recent increase, this is in comparison to a proportionally larger decrease which took place in the years prior to that period. Only a few decades ago, this species used to be found in a greater range of habitats than to which it is currently restricted.

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The Grasshopper Warbler

Grasshopper Warblers (often shortened to just Gropper) are renowned for the difficulty involved to see them. They have skulking habits, only really coming out into the open when the males sing their distinctive song. Most of the time they remain hidden in thick vegetation. In fact I’ve only seen this species twice before, and both times the birds were located by the loud song. The first time was a bird claiming its territory in May 2014 in a sand dune in Budle Bay, Northumberland and the second had probably only just arrived in the UK in April last year, when I found one singing in a garden at Selsey Bill in West Sussex from a small clump of ornamental pampas grass. In fact in the past 20 years Tony had only caught two or three, highlighting how lucky we were to catch this reclusive skulker.

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This was my only photo of a Grasshopper Warbler before Sunday, from Northumberland. This photo illustrates how hard-to-see Grasshopper Warblers are usually. And this one was, in relation to most other sightings, ‘showing well’!

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Donkey of the night

African Penguins were originally called Jackass Penguins not too long ago, in fact the bird book that I use for southern Africa includes them under that latter name. I have to admit I’ve always found that name slightly amusing, although I didn’t know why it was applied to Africa’s only breeding penguin until last week at the Stony Point colony.

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The African Penguins have adapted to their higher latitude environment by possessing a pink gland above their eyes, where blood rushes to in hot weather to hasten heat loss.

There are six species of penguins which have been recorded in Africa, predominantly in South Africa. All except for the African Penguin are vagrants. Even the African Penguin is quite localised, restricted by its requirement for predator-free islands or occasionally mainland sites. These mainland sites are always situated between a major town and the sea, to provide a barrier which predators cannot cross. Examples of these mainland colonies include Boulders Beach and Stony Point, with their barriers from predators being Simon’s Town and Betty’s Bay respectively. Therefore these colonies have only established recently as the towns have developed into a sufficient size, in fact both were founded in the 1980s and now contain between 2000 and 3000 penguins.

Stony Point was the colony we visited on our trip to South Africa. I would highly recommend it for anyone wanting to see the penguins in South Africa. It costs only 20 Rand (£1) to enter, and gives access to a long boardwalk which takes you directly through the colony. The penguins come so close that there are times when you are standing immediately above one which has chosen to shelter underneath the boardwalk! There are also a number of information boards along the boardwalk, one of which informed me of the etymology of the ‘Jackass’ Penguin: the species is known for its donkey-like braying sound which it often produces at night!

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Penguins, a section of the boardwalk and the outskirts of Betty’s Bay in the background

Humans have a long relationship with penguins, which has not always been good. This is particularly regarding guano collecting, which was a big business in the 19th century. Guano was very important during that era for farming as a manure to fertilise crops. It lead to the human colonisation of many offshore bird colonies as guano collecting became a full-time job. The problem with this in relation to African Penguins is that they nest naturally in burrows dug into guano, which therefore has to be very deep. If all the guano (often from other seabirds such as Cape Gannets or Cape Cormorants) has been removed by humans, then the penguins have nowhere to nest.

Fortunately, guano is no longer collected from areas where the penguins nest. Although, the guano layers are still not deep enough in many colonies for penguins to dig a nest. At Stony Point, we saw that artificial concrete nests had been installed. These nests are similar to a very large flowerpot lying on its side, half-buried. These have allowed the expansion of the colony where the quantity of guano available would have limited it.

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An example of one of the artificial nests.

There is another threat to African Penguins posed by humans. Sadly, this one is still an ongoing risk and very unpredictable: oil spills. Ships running aground can spill massive volumes of oil, which can severely harm seabird populations. Penguins are at a particular risk as they spend a lot of time near the surface of the ocean where the oil accumulates. The main problem the oil produces is that it impairs the waterproofing capabilities of the birds’ feathers. This exposes the birds to the full force of the water’s cold temperatures leading to hypothermia. Even the lucky ones who make it back to shore face consequences when they attempt to remove the oil from their feathers: it is often ingested and causes damage to the digestive system.

These threats among others have produced a catastrophic decline of 95% since the beginning of the 19th century, when 4 million penguins inhabited South Africa and Namibia. Now, there are only around 50,000 penguins left. At this rate of decline, we could see the extinction of the African Penguin in the wild by the year 2026 – just 8 years away.

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If the trend continues, this chick could be part of the eighth-to-last generation of African Penguins.

Fortunately there are a number of organisations working towards a happy ending for the African Penguin. Among these, SANCCOB is the predominant group performing rescue operations on penguins, particularly those affected by oil spills, while the Dyer Island Conservation Trust has opened the African Penguin and Seabird Sanctuary in Gansbaai which will act as a centre for research and education. I am hopeful that iconic African Penguin’s downward trend can be reversed.

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Not grousing about grouse

grouse
verb: to complain; to grumble

Yesterday I returned from a 17-day trip to Namibia and South Africa and after a string of special sightings, grousing is exactly what I wasn’t doing. One particular highlight was sightings of an order of birds I have never been lucky enough to encounter before.

Sandgrouse belong to the bird order Pterocliformes. This came about after they had previously been placed in two other orders. Firstly, they were included in the Galliformes, where the true grouse reside. They were placed here due to their anatomical similarities to the true grouse, although later on there was the realisation that this was not a result of genetic similarity but of convergent evolution (where two or more unrelated taxa evolve similar features, for example echolocation in the case of dolphins and bats). The next order they were included in was the Columbiformes which also contains pigeons and doves. This was because it was thought that they employed peristalsis in the oesophagus to suck up water – a pumping action which can draw liquid into the gullet – which is unusual in birds. Although now it is thought that this is incorrect, which stimulated the choice to place them in their own order.

There are sixteen species of sandgrouse species, found mostly in Asia and Africa. There are also some species in Europe such as Pin-tailed and Black-bellied which are found around the western Mediterranean. One has even made it to the UK: while most sandgrouse species are sedentary or make seasonal altitudinal movements at most, the Pallas’s Sandgrouse, which is usually found in central Asia, can be irruptive. Large irruptions have not been experienced in Europe for decades although they did occur regularly in the late 19th century. One irruption lead to thousands flooding into the UK and even breeding in a few locations.

As an order, they are well known for their drinking habits. Many species travel for miles to visit waterholes daily, where they can drink enough water in just few seconds to last them the 24 hours until the next visit. They are also famous for how they supply water to their young before they are able to fly to waterholes. The adult’s downy breast feathers are able to soak up lots of water, from which the chicks drink.

To avoid competition, different species visit waterholes at different times. This regularity makes waterholes ideal places to see many sandgrouse species with ease. During our stay at the Okaukuejo Camp in Etosha National Park, Namibia, we noticed that there was a poster by the reception which mentioned that Double-banded Sandgrouse visit the waterhole 40 minutes before sunrise and Namaqua Sandgrouse visit between 9am and 10am. We were lucky enough to have a chalet right next to the floodlit waterhole which is the main attraction at the camp. I was not going to refuse an opportunity to see my first sandgrouse species, so the next morning at 6.10 am I sat on a bench overlooking the waterhole. It wasn’t long before the first Double-banded arrived on the edge of the waterhole; at first it was only one or two at any time but before long there were at least thirty at once. Considering it was pitch-black everywhere around the floodlit waterhole, I was impressed.

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Due to the light my camera was set to a shutterspeed of 1/4, fortunately when they first landed the sandgrouse had a habit of staying stock still for a few seconds to check for danger before proceeding to drink.

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A female Double-banded Sandgrouse.

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Some sandgrouse smudges and a couple of less-blurry males.

After breakfast we headed out on a game drive on the semi-arid plains of the park. It was the dry season so waterholes were in low supply, so much so that individual ones are marked out on the map. At 9.45 am we arrived at the first waterhole of the day, on the edge of the Etosha Pan. This pan, when it wasn’t a pan, would have been the third largest lake in the world after the Caspian Sea and Lake Superior. It is not entirely known how the lake dried up however tectonic movements changing the course of the river that fed it seems to be the most plausible explanation. Nowadays, its dry, salt-encrusted state causes a few small water-bodies to draw in animals from a very wide radius.

Among the springbok, gemsbok and other mammals that this particular waterhole had attracted, I noticed a good number of what I originally thought were Cape Turtle Doves. Although after a closer inspection I realised that they definitely were not these but Namaqua Sandgrouse, at exactly the right time in the morning!

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The light was better for our sighting of the Namaqua Sandgrouse than for the Double-banded Sandgrouse, however the distance was compromised. This image shows a male on the left and a female on the right.

After having never previously laid eyes on these fascinating birds, seeing two species in just one day was certainly more than I expected. Although a few days later, it became evident that the trip was about to become even better for sandgrouse. We were at our final destination of the Namibia leg of our travels, a lodge named Ondekaremba near to the Windhoek Airport. We had dropped our bags off at the lodge before then returning the rental car at the airport (then subsequently hailing a taxi for our return to the lodge and a hotel transfer to the airport the following morning). We were beginning to think this was not a good idea as the access road to the lodge was a four-mile dirt track weaving through the bushveld and a dry riverbed which was unforeseen. However, it certainly became worthwhile when my mum spotted some movement on the side of the road. My dad, seated on the nearest side of the car to the birds, proclaimed that they were sandgrouse which lead to my panicked scramble across the backseats. By the time the car had come to a stop they were so close that I had to lean right out of the window to get a view of them below us. There were two, presumably a male and a female. The female was hard to see in the roadside grass although the male was walking slowly unobscured along the road itself. Compared to the poor light for the Double-bandeds and the distance involved with the Namaquas, I had no excuses with these birds. Luckily, in my opinion I don’t need any! What made this encounter even more memorable was the fact that they were a third species: Burchell’s! I couldn’t help feeling that my luck was well and truly in. Three out of the four species inhabiting Southern Africa in less than a week is not bad going.

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The male Burchell’s Sandgrouse.

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This species is known for travelling around 100 miles each day to its favourite waterhole.

 

 

 

 

 

Species no. 3000!

Admittedly Stratiotes aloides, known vernacularly as Water-soldier, is not the most desired plant to have in an ecosystem. It is possible that it is native in East Anglia and Lincolnshire however in Sussex, where this species became number 3000 on my pan-species list, it is more likely to be introduced.

Yesterday I joined the Sussex Botanical Recording Society on a visit to Court Lodge Farm on the Pevensey Levels, which possesses a rich assemblage of aquatic plants in the many ditches. Some special species recorded included Potamogeton obtusifolius (Blunt-leaved Pondweed) and Petroselinum segetum (Corn Parsley), the latter growing on the banks of the ditches rather than within them as was the case with the pondweed.

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An example of one of the ditches where we were recording. The majority of the water plants you can see in the photo would  be Lemna trisulca (Ivy-leaved Duckweed), Elodea nuttallii (Nuttall’s Waterweed) and the aforementioned Potamogeton obtusifolius (Blunt-leaved Pondweed).

Although despite these Levels specialities being present, for the ditches it is hard to escape the colonisation of several non-native invasive plants. Fortunately we didn’t come across any ditches which were dominated by these unwanted waterweeds however both Azolla filiculoides (Water Fern) and Hydrocotyle ranunculoides (Floating Pennywort) were found along with the robust growth of Water-soldier.

Water-soldier can be quite problematic for native flora. Small populations can, if left undisturbed by boats or large numbers of waterfowl, develop into armies. These can completely annex stretches of canals or ditches, out-competing ‘friendlier’ water plants for resources. The following quote is from the Water-soldier’s species account in the recently published Flora of Sussex: “On Pevensey Levels it has spread considerably, and in 2010 was found to be completely covering a ditch for several hundred metres”.

Despite this, I find its biology quite interesting. In the autumn it will begin to stop photosynthesising, and gradually lose the gas in its leaves that keeps it afloat. It will sink to the bottom of the ditch or canal where the water is unlikely to freeze. In the spring the increased strength of the sun’s rays will penetrate deep enough to allow the sharp, serrated, sword-shaped leaves to photosynthesise again, producing oxygen which gives the rosettes their buoyancy.

I was not originally planning to write a blog post on the Water-soldier until I realised today while inputting yesterday’s finds into my list that it fits into the 3000th slot. I am quite relieved that I have managed to reach this milestone, as the target I set myself in a blog post I wrote when I reached 2000 was to record my 3000th species before my 15th birthday. As of today I’m 14 years, 11 months and 1 day old. So I reached my target, but only just. It is hard for me to imagine stopping pan-species listing, however with upcoming GCSEs and A Levels I imagine I might have to slow down a little. But to keep it ticking, I have decided to set myself another target: 4000 by the end of 2019. Wish me luck!

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Two plants surrounded by Frogbit (Hydrocharis morsus-ranae) resembling miniature water-lilies.

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The snow-white flower of Water-soldier. The flowers are not seen too often, with the main method of reproduction being vegetative: the lowest leaves of the plant have axillary buds which will detach when the leaves decay and can disperse long distances before resprouting. This species is what’s known as dioecious – this means that male and female flowers are found on different plants. For some reason, there are very few if any male plants in England, so all reproduction in this country is vegetative as described above.

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The four or five plants in the photo here represent about half of the largest population of them I saw, luckily it hasn’t reached the levels of dominance seen at other parts of the Levels.

Sussex Rarities – Hairstreaks & Clubtails

This morning, having heard some exciting news on the website of the Sussex branch of Butterfly Conservation, I found myself in Ditchling Common Country Park, scanning bracken after bracken with my binoculars. I was looking for a Black Hairstreak or two. The windy and overcast conditions were not conducive to my hopes of sightings along the lines of the day-count of 98 that was made earlier in the month!

These numbers are quite extraordinary considering the fact that this species was only confirmed to be found in Sussex just over a week ago. Following a few battered individuals found at the same site last year, a survey has been undertaken to determine the presence of this colony. Its appearance here is particularly notable as this site is far from the existing distribution of this species in the UK. It is thought to be confined to a band of clay soil in the Midlands, mainly Cambs, Northants and Oxon.

The closest Black Hairstreaks have previously come to Sussex is Surrey, where they were introduced in the middle of the 20th century. However, the habitat at the introduction site was destroyed and the species disappeared there. The species is not known for their long distance movements or dispersal at all, in fact patches of identical habitat to where they are found elsewhere on the same site often go uninhabited due to the reluctance of the butterfly to travel long distances. Therefore it is thought that this colony is also an introduction similar to the Surrey one, although despite it only being discovered very recently it is likely that the species first appeared in the 1990s – this is because the expanse of the population at Ditchling Common suggests that it has been expanding for quite a while. It’s so slow that the rate of expansion, even of a healthy population, is estimated to be only about a kilometre per decade!

Now, back to this morning. The foodplant of the Black Hairstreak is Blackthorn, and it was in abundance at the country park. This was especially true at a corridor that extends from the fish pond south-west to the Folders Lane East. This was where we focused our searching, which turned out eventually to be the right idea. At 10.30 the sunshine finally made a prolonged appearance and the wind died down slightly. This appeared to trigger the daily emergence of the hairstreaks to warm up on the bracken. The first one we found was perched at quite a gradient on one of the fronds, perfectly angled towards the sun. After a few minutes of sitting very still, it switched sides rather in the fashion of a sunbather aiming for an even tan. As it had not yet gained enough thermal energy it was being quite ‘co-operative’, allowing for great views. This sighting was repeated with up to three other Black Hairstreaks, a very satisfying way to see a new butterfly species for me: not a common occurrence!

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Although the sexes are hard to differentiate on physical appearance, it is likely that those we found were females. The males will emerge earlier, in order to have established a territory prior to the emergence of the females. They will fiercely defend their territory, which is usually centred around an oak known as the ‘master oak’, and approaching the end of the flight period this activity will render them quite battered and damaged. It is likely that this species is past its peak already this year. The species’ very short flight period is one reason why this colony may have remained undiscovered for such a long period of time. Years where the population is dramatically increased compared to previous and following years are also characteristic of this species. It is likely that this year is one of these ‘boom years’ which is what may have lead to this year being the one in which this colony was finally discovered. So if you haven’t yet had a chance to visit this true Sussex rarity, I would recommend that you do so sooner rather than later. Their short adult stage will be over before the end of June, and in future years there probably won’t be as many as there have been this year.

Black Hairstreaks are not the only entomological rarity I’ve had the good luck to see in Sussex this month. At the beginning of the month I took a walk along a small stretch of the River Rother, near Fittleworth in West Sussex. Having been advised about their presence there by Amy Robjohns and Olly Frampton, I was on the lookout for Common Clubtails, a species that isn’t actually as common in the UK as its name suggests. On the British Dragonfly Society website it is described as “extremely local”, only being found on a few rivers in Wales and southern and central England.

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However, its scarcity on a national basis was certainly not evident along this tranquil, luscious river in the mid-morning sun. Along only a few hundred metres of the river we managed to find at least 10 either hunting along the river or perched on bankside vegetation and overhanging willows. The vast majority were males which were patrolling their recently acquired territories while many females would be seeking protection in the nearby woodlands away from the water. They will soon return to mate and lay a new batch of eggs, which will complete their immature stages in the silty riverbed within 3-5 years.

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Orchid on the Hill

The Early Spider-orchids Ophrys sphegodes at Castle Hill NNR have one of the best views of the South Downs as well as Brighton to their south-west. On the northern edge of Woodingdean, a chalk grassland slope supports this nationally scarce species, which has only a scattered distribution along the South Coast from Dorset to Kent.

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This orchid is named after its appearance, with its flowers apparently resembling the abdomen of orb-weaver spiders. However, its flower shape has evolved so that it resembles bees, which come to try and mate with the flower, known as pseudo-copulation. This is also the case in the perhaps more appropriately named Bee Orchid for example. To complement the shape of the flower, these orchids also release the scent of female bees which further entices the male bees to unknowingly pollinate the plants.

However this technique may show to be detrimental towards the success of the species in the face of climate change. Despite the strength and accuracy of the scents wafted by the flower, they cannot compete with actual female bees. Therefore, the plants most likely to pollinate and reproduce successfully are those which blossom after the male bee has emerged although before the females. Although sadly warmer spring temperatures are pushing the phenology (life cycles) of these two species out of sync.

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It is also interesting to observe the variation in the exquisite patterns shown on different individual flowers, such as these:

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Travelling to find these orchids (a new plant for me) was a perfect break from revision. Despite their rarity, there are several reliable sites such as Durlston Country Park and Dancing Ledge in Dorset, Samphire Hoe in Kent and of course where I visited today, Castle Hill NNR in East Sussex. I would definitely recommend looking for them before they stop flowering in early June!

 

The Conservationist’s Battleground

It’s just past midday and in the 35 degree heat, we drive along the National Highway-29 with an expanse of wild floodplain to our north and forested highlands to our south. As we pass a small, one-man roadside fortification, a shooting post, we are told about this area’s ever-present war. This is not just a deterrent where untrained local militia shoot at an intruder’s feet to ward them off. Someone was fatally shot here the previous night, as they are every few weeks.

‘The Pride of Assam’ roams the Kaziranga National Park we had just exited. With an alleged higher potency than the horns of its African counterpart, it is in particularly high demand in Asian countries, especially Vietnam, where it is used as a supposed cure for cancer. Its value is highlighted by the risks the poachers will take to harvest it. Approximately the same number of people are killed by the anti-poaching force each year as their quarry are by poachers: the Greater One-horned Rhinoceros.

The Greater One-horned Rhinoceros, also known as the Indian Rhinoceros, is one of five rhino species worldwide, with three being found in Asia. Every species has experienced declines.

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Adult female Greater One-horned Rhinoceros in Kaziranga National Park

The Javan Rhinoceros is one of the rarest large mammals in the world. It used to be widespread in south-east Asia, with its range stretching from the Sunderbans in east India, east to the Vietnam coast and south to Central Java. Now, only around 120 years  since it first became locally extinct in India, the sole remaining population inhabits the Ujung Kulon National Park. The park has an area of 1200 square kilometres, of which about a third is marine and supports as few as 60 Javan Rhinos.

The Sumatran Rhinoceros is only slightly less rare. It once had a similar range to the Javan Rhinoceros, and although it didn’t inhabit Vietnam, it was found in Borneo, where one of the four or five populations is located. Although there are more individual populations than the Javan Rhinoceros, these are tiny and probably add up to fewer than 100 individuals.

Fortunately, the Greater One-horned Rhinoceros is approaching 4000 individuals having almost doubled over the past couple of decades. Despite this, as with the other two species we have looked at, the distribution has decreased from a wide band ranging from Pakistan to the easternmost point of India to several scattered pockets in south Nepal, West Bengal and along the Brahmaputra River in Assam; and there is a chance there is a population in the Royal Manas National Park in Bhutan.

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One of the first rhinos we saw in Kaziranga National Park

The increase in the population of this species is at least partly due to the work of anti-poachers around the populations of this rhino, particularly around the national parks where many of the rhinos live. Nepal is an excellent example where the holy grail of zero-poaching has actually been achieved, where several very popular species in the markets of Vietnam and other East Asian countries such as Tiger, Asian Elephant and Rhinos live. With almost a quarter of the country assigned as national parks and other protected areas such as Bardiya NP and Chitwan NP, where I was lucky enough to see both Tiger and Rhino several years ago, and a huge commitment from the authorities, it has illustrated that the war against poaching doesn’t have to be an insurmountable battle.

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Inhabitants of the many river sandbanks along the Brahmaputra River. In some places such as near Chitwan National Park, children are being educated about conservation with projects such as Eco Clubs in schools.

In my opinion Kaziranga National Park and other areas in India which support the Greater One-horned Rhino may soon realise the abolition of poaching. If the anti-poaching rangers continue risking their lives to save this magnificent animal, and other approaches such as monitoring and education continue to be implemented, then this rhino may just survive and perhaps even prosper.

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Mother and calf on the misty plains of elephant-grass.