Category: United Kingdom

Common Dolphin

Common Dolphin

  • The most abundant cetacean in the world, with around 6 million (it should be noted that there are 1350 humans in the world, for every individual common dolphin).

Despite this fact and its name, the common dolphin is not thought of as the model dolphin (that honour goes to the bottlenose dolphin due to its popular appearances in aquaria and the media). It did, however, feature heavily in Ancient Greek and Roman art and culture, most notably in a mural painted by the Greek Minoan civilization.

It is currently the only member of the genus Delphinus. The common dolphin belongs to the subfamily Delphininae, making this dolphin closely related to the three different species of bottlenose dolphins, humpback dolphins, striped dolphins, spinner dolphins, clymene dolphin, spotted dolphins, fraser’s dolphin and the tucuxi and guiana dolphin.[5] The common dolphin was originally categorized into two different species (now thought to be ecotypes), the short-beaked common dolphin and the long-beaked common dolphin. However, recent evidence has shown that generally long-beaked dolphins of this species have originated from the short-beaked population, and therefore there is no close links between different long-beaked dolphins in any part of the world.

Currently, the common dolphin is divided into four subspecies:

  • D. d. delphis, the nominate subspecies
  • D. d. bairdii, the Eastern North Pacific long-beaked common dolphin
  • D. d. ponticus, the Black Sea common dolphin
  • D. d. tropicalis, the Indo-Pacific common dolphin

A number of fossils were erroneously placed in the same genus, but this has since been corrected. 

Common dolphins can live in aggregations of hundreds or even thousands of dolphins,though are often seen in groups numbering several hundred individuals (with subgroups consisting of 20-30 individuals). Occasionally, different groups will come together to form mega-pods which can consist of over 10,000 dolphins – quite a site to witness. Genetic studies in the Northeast Atlantic suggest that common dolphin pods generally do not consist of close kin, but rather of members that are not closely related. Unlike many delphinids, common dolphins do not live in a matriarchal society. That being said, closely related individuals are usually found in similar geographical locations fairly consistently, providing evidence that this species displays site fidelity (at least in the North-eastern Atlantic). Male common dolphins display greater site fidelity in relation to their kin than females.

Common dolphin pod structure often consists of nursery pods (which includes females and calves), bachelor pods (consisting of all males) and mixed groups of males and females, including sub-adults and calves. Genetic evidence seems to indicate that common dolphins live in fission-fusion societies, where dolphins form pods that are not necessarily stable and do not necessarily consist of related individuals. It is not known if common dolphins form lifelong bonds with other individuals  like the long-term male alliances seen in bottlenose dolphins.

There is some evidence that common dolphins use signature whistles, similar to that of the bottlenose dolphin. These whistles are believed to serve as an acoustic label the dolphin equivalent of a name.  It takes approximately 1 year for a calf to learn its signature whistle after which it remains stable for the rest of a dolphin’s life.

In South Africa, as many as 29 common dolphin signature whistle types were detected. However, it was difficult to determine if each dolphin had its own signature whistle due to the vast number of dolphins present (over 1,000) and anthropogenic background noise. Additionally, considering the vast number of dolphins present and  taking into account their feeding and diving behaviour, it appears that common dolphin signature whistles are also used for group cohesion. Another hypothesis for the function of signature whistles, is that they serve as a beacon for lost individuals.

Common dolphins sometimes associate with other dolphin species, such as pilot whales (note, not actually whales). In the Gulf of Corinth, common dolphins frequently display mixed species association, especially with striped and Rissos’ dolphins. Over one third of all dolphin sightings in the gulf consisted of mixed species associations that partially consisted of common dolphins. In mixed species associations, the ratio of striped to common dolphins ranged from 6-11:1. When Rissos’ dolphins were present (there would usually be only one or two individuals), it appeared that much of their scars were the result of interactions between striped and spinner dolphins. In much of the interactions, the Rissos’ dolphins would chase and herd the common dolphins toward the boat, while the common dolphins would try and swim under the Rissos’ dolphin. When groups of common and striped dolphins would charge at each other, the Rissos’ dolphin would chase the striped dolphins. Sometimes these interactions appeared to be playful, and at other times aggressive. Synchronized swimming and surfacing was commonly observed. These interactions take place in the deepest part of the Gulf, furthest from shore and usually consist of a total of 60 dolphins from all three species.

There have been 15 cases of common dolphin and striped dolphin hybrids being recorded. Genetic and observational evidence has demonstrated that the hybrids are fertile and are capable of not only reproducing with other hybrids, but are capable of reproducing with each of the parent species. Striped dolphins have been known to mate with other dolphins, as the Clymene dolphin is the result of hybrid speciation between striped and spinner dolphins. However, this is unlikely to happen with common dolphins, as their population in the Gulf of Corinth is too low. Common dolphins and bottlenose dolphins have been known to interbreed in captivity. There is one confirmed case of a hybrid between a bottlenose and common dolphin in Southern Spain, an important feeding ground for both species. The mother was a female bottlenose dolphin (dubbed as Billie) who has spent 10 years within a common dolphin pod. Billie was observed assisting common calves reach the surface at three different intervals and would babysit the calves after the mother went through labour. They have also been observed bow riding on baleen whales, and they also bow ride on boats. They are fast swimmers and breaching behaviour and aerial acrobatics are common with this species. They are also known to display altruistic behaviours to support injured members.

The short-beaked common dolphin is pregnant for 10 to 11 months. The new-born calf has a length of 70 to 100 centimetres (2.3 to 3.3 ft) and weighs about 10 kilograms. For the Black Sea population, weaning occurs at between five and six months, but occurs later (up to about 19 months) in other areas. Typical interbirth interval ranges from one year for the Black Sea population to three years for eastern Pacific Ocean populations. Age of sexual maturity also varies by location, but can range between two and seven years for females and three and 12 years for males. No evidence exists of any major reproductive differences between the two species. In captivity, the long-beaked common dolphin has hybridized with the common bottlenose dolphin . One of the hybrids has been bred back to a bottlenose dolphin, demonstrating such hybrids are fertile.

Find our news section below this video of a megapod of common dolphins

Striped Dolphin

Striped Dolphin

The striped dolphin (sometimes called the Euphrosyne dolphin) has been heavily researched and is found in temperate and tropical waters around the world. It has (until recently been included in the genus Stenella, but it has been shown to actually be an oceanic dolphin. According to a recent study, the closest relatives of the striped dolphin are the Clymene dolphin, the common dolphins, the Atlantic spotted dolphin, and “Tursiops” aduncus, which was formerly considered a subspecies of the common bottlenose dolphin. The striped dolphin was described by Franz Meyen in 1833.

A striped dolphin leaps in the Mediterranean Sea off Toulon

The striped dolphin has a similar size and shape to several other dolphins that inhabit the waters it does (see pantropical spotted dolphin, Atlantic spotted dolphin, Clymene dolphin). However, its colouring is very different and makes it relatively easy to notice at sea. The underside is blue, white, or pink. One or two black bands circle the eyes, and then run across the back, to the flipper. These bands widen to the width of the flipper which are the same size. Two further black stripes run from behind the ear — one is short and ends just above the flipper. The other is longer and thickens along the flanks until it curves down under the belly just prior to the tail stock. Above these stripes, the dolphin’s flanks are coloured light blue or grey. All appendages are black, as well. At birth, individuals weigh about 10 kg (22 lb) and are up to a meter (3 feet) long. By adulthood, they have grown to 2.4 m (8 ft) (females) or 2.6 m (8.5 ft) (males) and weigh 150 kg (330 lb) (female) or 160 kg (352 lb) (male). Research suggested sexual maturity was reached at 12 years in Mediterranean females and in the Pacific at between seven and 9 years. Longevity is about 55–60 years. Gestation lasts about 12 months, with a three- or four-year gap between calving.

In common with other dolphins in its genus, the striped dolphin moves in large groups — usually up to thousands of individuals in number. Groups may be smaller in the Mediterranean and Atlantic. They may also mix with common dolphins. The striped dolphin is as capable as any dolphin at performing acrobatics — frequently breaching and jumping far above the surface of the water. Sometimes, it approaches boats in the Atlantic and Mediterranean, but this is dramatically less common in other areas, particularly in the Pacific, where it has been heavily exploited in the past. Striped dolphins are known as “streakers” throughout the eastern tropical Pacific due to their behavior of rapidly swimming away from vessels to avoid collisions.

The striped dolphin feeds on small pelagic fish and squid.

Striped dolphins jumping in the Gulf of Corinth

The striped dolphin inhabits temperate or tropical, off-shore waters. It is found in abundance in the North and South Atlantic Oceans, including the Mediterranean (sightings and strandings have been reported rather recently in Sea of Marmara[6]) and Gulf of Mexico, the Indian Ocean, and the Pacific Ocean. Roughly speaking, it occupies a range running from 40°N to 30°S. It has been found in water temperatures ranging from 10 to 26 °C, though the standard range is 18-22 °C. In the western Pacific, where the species has been extensively studied, a distinctive migration pattern has been identified. This has not been the case in other areas. The dolphin appears to be common in all areas of its range, though that may not be continuous; areas of low population density do exist. The total population is in excess of two million. The southernmost record is of a stranded individual nearby Dunedin, southern New Zealand in 2017.[7]

Japanese whalers have hunted striped dolphins in the western Pacific since at least the 1940s. In the heyday of “striped dolphin drives”, at least 8,000 to 9,000 individuals were killed each year, and in one exceptional year, 21,000 individuals were killed, though since the 1980s, following the introduction of quotas, this number has fallen to around 1,000 kills per year. Conservationists are concerned about the Mediterranean population which is threatened by pollution, disease, busy shipping lanes, and heavy incidental catches in fishing nets such as long-liners, trawlers, gill nets, trammel and purse seine nets. . Recent threats include military sonar, and chemical pollution from near by harbours. Hydrocarbons are also a major concern such has PCBs (polychlorinated biphenyls) and HCB (hexachlorobenzene). These are said to give problems to additional food chains as well as doing a full body test to see what hydrocarbons may be passed down through parturition and lactation. Attempts have been made to keep the striped dolphin in captivity, but most have failed, with the exception of a few captured in Japan for the Taiji Whale Museum.

Striped dolphins are one of the targeted species in the Taiji dolphin drive hunt.

The adult striped dolphin eats fish, squid, octopus, krill, and other crustaceans. Mediterranean striped dolphins seem to prey primarily on cephalopods (50-100% of stomach contents), while north-eastern Atlantic striped dolphins most often prey on fish, frequently cod. They mainly feed on cephalopods, crustaceans, and bony fishes. They feed anywhere within the water column where prey is concentrated, and they can dive to depths of 700 m to hunt deeper-dwelling species.

 

Small numbers of dolphins live nearby Gijón

The eastern tropical Pacific and Mediterranean populations of the striped dolphin are listed on Appendix II  of the Convention on the Conservation of Migratory Species of Wild Animals (CMS), since they have an unfavourable conservation status or would benefit significantly from international co-operation organized by tailored agreements.[9]

On the IUCN Red List the striped dolphin classifies as vulnerable due to a 30% reduction in its subpopulation over the last three generations. These dolphins may also be an indicator species for long term monitoring of heavy metal accumulation in the marine environment because of its importance in the Japan pelagic food web as well as its ability to live for many years. Various other groups have signed memorandum, agreeing not to hunt them.

Conservation efforts have included having ship lines take a new path to their destination such as cruise lines as well as reduced human interaction close up. Feeding the dolphins has also become a problem, and has led to behavioural changes. This has also been suggested as another reason for mortality events.

The striped dolphin once thrived, numbering 127,880 before 1990. Since then, the population has suffered from incidental catches in fisheries. Mortality has been considered unsustainable, but there is a lack of data which hampers conservation efforts.

Various cases of stranding over the years have been a cause for alarm. With an unfavourable conservation status and the increasing amount of debris piling in the ocean every year, striped dolphin’s population is decreasing. 37 dolphins stranded off the Spanish Mediterranean coast were suffering from dolphin morbillivirus (DMV). The causes of these stranding have been changing from epizootic to enzootic.

There is a suggestion that theses strandings are caused by a virus, and that the virus is becoming more common.

Forest of Dean

Forest of Dean - Boar Watching

The Forest of Dean is perhaps one of the biggest and healthiest woodlands within the UK.

Part of this is down to its significant population of wild boar.

Before humans hunted wild boar to extinction, they were a highly important part of our ecosystem, and generally woodlands in the UK show their absence.

What do I mean? One of the benefits of wild boar is that their rooting behavior. While humans often do not like this, as this rooting behavior can destroy gardens or picturesque roundabouts,  areas that have had this treatment are perfect for trees to germinate and start to grow.

Indeed we were astounded walking around the forest to see so many small copses of new tree nurseries. In this sense wild boar fulfill a similar niche of being ecosystem engineers as beavers in rivers.

Apart from the boar, there is a healthy population of deer. Roe deer exist here naturally. Fallow deer were introduced by the Normans and this is the most common species to see. In recent years Muntjac deer have also recently become established and are fascinating. There are a small number of red deer that still exist though seeing these is a lucky day.

Adult rooting with boarlets (or as some call them Humbugs)
One of the big advantages of boar presence is a reduction of ground cover

Wild boar are surprisingly large animals and we have had a couple of encounters with them on our visits.

The best way to spot them is by driving some of the back roads in the early evening.

I have once spotted a family from the car, and this year two boar ran past while we were walking a forest path.

Both were in a similar location. I will put together a page of information that will be sent with any booking made from the accommodation further down the page, or I can provide just this information for £10 if you have found a place to stay elsewhere.

View of the forest
River Wye running through
Boar track among dog tracks
Dung beetle at work
Droppings - Pine marten?
More rooting behavior signs

The Forest of Dean is a truly wild woodland. While it is scattered with villages and towns, this is the only place I have seen beetles actually behaving as dung beetles, in the UK.

The government has also started a process of translocating pine martens to the area, and while the animal is shy, signs of its presence will increase over the next few years. If the translocation is successful, then it will also slowly remove the grey squirrels from this wood, which apart from being good for the health of the trees, will allow red squirrels to recolonize.

Visiting a place like this allows you to hunt for signs of the animals such as tracks, as well as spotting the actual animal itself.

Boar are highly intelligent, and fascinating to see. Care should be taken as they can be dangerous, particularly when they have young.

Places to stay

Below is a variety of lodgings which are close to wild parts of the forest. There is also a link to search all accommodation available within the forest of dean. Any bookings support the work of the site. The places we have listed are close to where we have had our sightings, however boar are found throughout the forest so do not feel restricted to just the places we listed.

Campsites will be listed below the hotels.

Link to search all available lodgings listed on booking.com throughout the Forest of Dean
Inglewood House Monmouth, prices from £90
Demense Farm Guesthouse, monmouth, prices from £122
Raglan Lodge, Monmouth, prices from £40
[booking_product_helper shortname=”forest of dean”]
Forest Walk Coleford, prices from £60
Lodge rooms, Coleford, prices from £80
Bell Hotel Coleford, Prices from £60
Angel Hotel Coleford, Prices from £99

Campsites coming soon

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Devon river otter – beavers

River Otter in Devon - Beavers

Beavers can be seen once again, living wild in the UK. This is fantastic news for the cleanliness of our rivers. Despite rumours spread about their impacts on fish the beavers return is fantastic for the health of the river. Furthermore, beaver dams often make great nursaries for fish fry.

Young beaver, sighted in the middle of the day

The UK is missing much of its wildlife, that once lived here. Humans have gradually eliminated much of the mammals that we once shared this country with. In particular, in England we have lost almost all large wilderness ecosystems, which makes it hard to reintroduce mammals we pushed to local extinction.

However, beavers are an exception. Being water mammals, they live in rivers – places that we cant grow crops anyway.

People have argued that they would dam large numbers of rivers, and flood vast landscapes, making it impossible for fish to migrate up stream (bizarrely forgetting that beavers and fish have coexisted in the UK and the rest of Europe for millions of years). However in Europe, one of the most useful things that Beavers do, is reduce the height of flooding, and largely eliminate flash flooding. Indeed, a village in Wales that had been flooded for three years in a row, set aside 10 acres above the village and introduced a family of beaver, and there have been no floods since then.

Back in 2008 a family of beavers appeared on the River Otter. The government immediately said that they needed testing for diseases, but would not be allowed to return regardless of the outcome. The village complained, and eventually the beavers were given five years of living on the River Otter, during which time a study would be carried out.

Initially, there was concern we did not know the origin of these beavers. Genetic analysis showed that they were European beavers, and a health check showed them to be clear of illnesses that can afflict them.

As expected, the beavers were highly beneficial. They have thrived on the river, and now around 30 lives in the original stretch of river, there are now thought to be between 300 and 500 living wild in Devon and this number is only increasing. They have increased biodiversity, slowed river flow and improved water quality. Recently they were given the right to remain permanently by the British government. Given the space, beavers will likely return to all parts of the UK in the next few decades.

A clear view of the young beaver's tail
We could see these beavers in the entrance to their lodge

Beavers are wonderful animals to watch. As environmental engineers they change the river and surrounding area, and these changes are often highly beneficial for other animals. In Europe, beaver pools are often very good for fish nurseries, as well as being highly popular for both water voles and otters.

The beavers on the River Otter are no different. I recently spent some time with my family on this river watching the beavers.

As with any wildlife trip, I had done extensive research so knew roughly where to look.  However we found it surprisingly easy to find them.

Beavers make a  fantastic introduction to wildlife watching for small children. This is because they are reasonably predictable, most active in the early morning and early evening.

Also, given their security of being safe in the water  you can sit or stand on one bank and watch them on the  opposite bank, and they will happily get on with their own lives.

My children are six and eight and in a weekend we saw the beavers perhaps six times for a total of around an hour. Their excitement was wonderful to see

A walk along the bank of the River Otter may well lead to a sighting. However if you are in the right place, you are highly likely to see them. 

Below are a series of links for you to use on your visit. These should help you find a place to stay nearby.

I will put together some brief information about where we have encountered beavers, and where we found the dams. The cost will be £10, though if you book accomodation through one of the links below it will be reduced to £5. 

The area where the beavers live is covered in villages. Generally these are small so staying anywhere in the area is good. The maps hows all booking.com listed places, or indeed use the blue enclosed search link.

Beaver dam
Dam with flooded wood

Places within Ottery St Mary

Tumbling Weir Hotel, Ottery St Mary. Click image for more
The Wheel House, Ottery St Mary, click image for more
Search booking.com for devon hotels

This is a rural area, so hotels are not exactly where the beavers live. However, beavers have spread throughout the river otter valley, and there are now thought to be around 30. Use the above link to access rest of the hotels in the area, and the map below to see what is available

[booking_product_helper shortname=”river otter beavers”]

 

 

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