Tag: mammal

Aragualan River Dolphin

Araguaian river dolphin by Rio Cicica

Araguaian river dolphin

The Araguaian river dolphin or Araguaian boto  is a South American river dolphin population native to the Araguaia–Tocantins basin of Brazil.

The recognition of I. araguaiaensis as a distinct species is still debated. It was originally distinguished from the Amazon river dolphin in January 2014. On the basis of nuclear microsatellite and mitochondrial DNA data as well as differences in skull morphology (it generally has a wider skull). It also differs from the Amazon and Bolivian river dolphins in the number of teeth per hemimandible (24–28 versus 25–29 and 31–35, respectively).

River dolphins have a complex set of acoustic calls that help shed light on their personalities, behaviours and interaction with other river dolphins. In a study by Gabriel Melo-Santos et. Al they analysed frequency contours of 727 signals They found that these signals had a critical similarity value of 96% and frequency contours were categorized into 237 sound-types. Interestingly the most notable and frequent sounds were emitted when calves were present shedding light on a close and complex mother child relationship. The findings show that the acoustic sounds of river dolphins are incredibly complex and are similar to those of by social delphinids, such as orcas and pilot whales.

The total population of the species is estimated to be of the order of 600 to 1500 individuals, and genetic diversity is limited.[4] The ecology of its habitat has been adversely affected by agricultural, ranching and industrial activities, as well as by the use of dams for hydroelectric power. The inhabited section of the Araguaia River probably extends over about 1500 km out of a total length of 2110 km. The Tocantins River habitat is fragmented by six hydroelectric dams, so the population there is at particular risk.[4] The authors of the discovery paper regard its probable eventual IUCN status to be Vulnerable or worse.

The largest number of individuals of the new species is likely to occur in and around Cantão State Park, which contains most of the lakes in the Araguaia basin. However, commercial fishermen around the park have been killing them because they sometimes steal fish from nets. Shooting is common, but around protected areas like Cantão, where the sound of a gun might attract park rangers, some fishermen have taken to putting out poisoned bait for dolphins. The southernmost population of the species is a small group of isolated individuals in the Tocantins river above the Serra da Mesa dam.

Below you will find a list of any articles which mention this species specifically, below that is a video of this species in the wild. Below this, we will list any tourism opportunities (if any that we connect with).

Amazon River Dolphin

Amazon river dolphin by Oceancetaceen sometimes known as the Orinoco

Amazon Dolphin

The Amazon river dolphin, (other names include boto, bufeo or pink river dolphin), is a species of toothed whale endemic to South America and is classified in the family Iniidae. Three subspecies are currently recognized: Amazon river dolphin,, Bolivian river dolphin and the Orinoco river dolphin while position of Araguaian river dolphin  within the clade is still unclear The three subspecies are each found in a separate river basin (in order) the Amazon basin, the upper Madeira River in Bolivia, and the Orinoco basin.

The Amazon river dolphin is the largest species of river dolphin, with adult males reaching 185 kilograms (408 lb) in weight, and 2.5 metres (8.2 ft) in length. Adults acquire a pink colour, more prominent in males, giving it its nickname “pink river dolphin”. Sexual dimorphism is very evident, with males measuring 16% longer and weighing 55% more than females.

Like other toothed whales, they have a melon, an organ that is used for bio sonar. The dorsal fin, although short in height, is regarded as long, and the pectoral fins are also large. The fin size, unfused vertebrae, and its relative size allow for improved manoeuvrability when navigating flooded forests and capturing prey.

They have one of the widest ranging diets among toothed whales, and feed on up to 53 different species of fish, such as croakers, catfish, tetras and piranhas. They also consume other animals such as river turtles, aquatic frogs, and freshwater crabs. However, this is not particularly surprising, as there are so many forms of life in the Amazon rainforest, and plenty is likely to occasionally find themselves in the river.

In 2018, this species was classed as endangered, by the IUCN with a declining population. Threats include incidental catch in fishing lines, direct hunting for use as fish bait or predator control, damming, and pollution; as with many species, habitat loss and continued human development is becoming a greater threat.

While it is the only species of river dolphin kept in captivity, almost exclusively in Venezuela and Europe, it is difficult to train and often die very young, when kept in captivity..

Life expectancy of the Amazon river dolphin in the wild is unknown, but in captivity, the longevity of healthy individuals has been recorded at between 10 and 30 years. However, a 1986 study of the average longevity of this species in captivity in the United States is only 33 months. An individual named Baby at the  Duisburg Zoo, Germany, lived at least 46 years, spending 45 years, 9 months at the zoo.

Below you will find any news articles on Amazon dolphin (though articles with both words also get sucked in). Also  we will add any information on where you can go to see these in the wild, beneath both of these.

Orca or Killer whales

Orca by Robert Pittman NOAA

Orca or Killer whale

As this species is a member of Cetacea, not carnivora. Never-the-less, this is the largest clear predator on the planet.

They are found in all of the worlds oceans. What is incredible, is that other apex predators, like the great white are rendered prey, simply be the arrival of Orcas on the scene.

One such example, is the arrival of the Orcas in South Africa. The great white sharks have vanished. While there are suggestions that they have not gone far (perhaps merely into the depths of the waters nearby)  it is clear that after a number were killed by the orcas they have given way.

They are not actually whales, being the largest member of the Oceanic Dolphin family, and as such appear to have the brainpower to defeat almost anything when they put their mind to it. As well as great white sharks, Orca will also hunt all of the baleen whales, including the blue whale which is the largest animal to ever roam the earth. They will also regularly hunt toothed whales such as false killer whales.

Each pod is lead by a dominant female, and these animals can live to be 50-90 years old. While this species eats a wide variety of fish, sharks, rays and marine mammals such as seals, other species of dolphins and whales, generally these animals specialize. Some generally eat fish, while others hunt mammals.

They have a wide range of hunting techniques, from polar orca working together to create waves to wash seals off icebergs, to intentionally beaching themselves in Argentina, to grab seals from the beach. Each group is capable of coming up with their own techniques which are taught to future generations.

Below you will find any articles from the blog, which mention the Killer whale (or Orca). Below that is a video of this species (it is a 50 minute documentary on this species). Below that, we will add any links which will allow you to try to see this species for yourself.

Southern right-whale dolphin

Southern right whale dolphin by Alcide Dessaines D' Orbigny

Southern right-whale dolphin

The southern right whale dolphin  is a small and slender species

 

 of cetacean, found in cool waters of the Southern Hemisphere. It is one of two species of right whale dolphin. This genus is characterized by the lack of a dorsal fin. The other species, the northern right whale dolphin, is found in deep oceans of the Northern Hemisphere and has a different pigmentation pattern than the southern right whale dolphin.

Southern right whale dolphins can be easily distinguished from other cetacean species within their range as they are the only dolphins without dorsal fins in the Southern Hemisphere. They have streamlined and graceful bodies, a single blowhole and a short and defined beak, possessing between 39 and 50 teeth per row.

A sharp dividing line separates the black dorsal part from the white ventral part of the body, running from the tail stock forward,  dipping down to the flipper insertion and sweeping back up, below the eyes, to cross the melon between the blowhole and snout crease. Younger individuals can be grey/brownish dorsally but develop adult coloration within the first year. The flippers of the southern right whale dolphins are small, recurved, predominantly white and located about one-quarter of the way back from the snout tip. Their flukes are small, have a white underside and dark grey upper side, with a notch in the middle and concave trailing edges.

There are no current global abundance and mortality estimates of the species although it is considered a fairly common and abundant species along its range, particularly in Chile. The very low sighting rate is most likely caused by a lack of sampling effort and due to the difficulties of sighting the animals in their offshore habitat.

Northern right-whale dolphin

Northern rhight whale dolphin

The northern right whale dolphin is a small, slender species of cetacean found in the cold and temperate waters of the North Pacific Ocean. Lacking a dorsal fin, and appearing superficially porpoise-like, it is one of the two species of right whale dolphin.

Northern right whale dolphins are fast swimmers. Their average swimming speed is around 26 km/h (16 mph) but they can reach speeds of up to 30–40 km/h (19-25 mph).
When travelling fast, a group looks as though they are bouncing along on the water, as they make low, graceful leaps together, sometimes travelling as far as 7 m in one leap. They can dive up to 200 m (660 ft) deep in search of squid and fish, especially lanternfish. Additionally,  also feeds on other prey items, such as Pacific hake, saury and mesopelagic fish.

It is estimated that a total of around 68,000 northern right whale dolphins inhabit the Pacific Ocean. Of those, around 26,000 (the geometric mean of their abundance estimates in US waters from 2008-2014) are placed into the California/ Oregon/ Washington stock for management purposes. Their minimum population estimate is around 18,600. Their abundances and distributions along the US coast do not only vary seasonally but also interannually, making the identification of population trends difficult.

Below is a list of any articles from this site, which mentions this species. Below that, is a video of the species in question. Below both of these we hope to add links which will help if you are looking to see this animal in the wild.

Hectors Dolphin

Hectors Dolphin photo by Avenue

Hectors Dolphin

Hector’s dolphin  is one of four dolphin species belonging to the genus Cephalorhynchus. Hector’s dolphin is the only cetacean endemic to New Zealand, and comprises two subspecies: C. h. hectori, the more numerous subspecies, also referred to as South Island Hector’s dolphin; and the critically endangered Māui dolphin (C. h. maui), found off the West Coast of the North Island.

It is the smallest dolphin species with adults length between 1.2 and 1.6m. The species’ range includes murky coastal waters out to 100 m (330 ft) depth, though almost all sightings are in waters shallower than 50 m (160 ft). Hector’s dolphins display a seasonal inshore-offshore movement; favouring shallow coastal waters during spring and summer, and moving offshore into deeper waters during autumn and winter. They have also been shown to return to the same location during consecutive summers, displaying high foraging site fidelity. The inshore-offshore movement of Hector’s dolphins are thought to relate to seasonal patterns of turbidity and the inshore movements of prey species during spring and summer.

There are 2 subspecies,

  • South Island Hectors dolphin – Threatened, and with a decreasing population, currently thought to number around 10,000
  •  Maui dolphin – critically endangered, population under 50.
These diverged 50,000-60,000

Below, you will see a list of articles on this subject, and below that, you will see a video on this species

Below both of these, we will add links and information (as we get it) so that you can see these dolphins if you are in the area.

Haviside Dolphin

Haviside dolphin by Joachim Huber

Haviside Dolphin

Heaviside’s dolphin is one of four dolphins in the genus Cephalorhynchus. The small cetacean is endemic to the Benguela ecosystem along the southwest coast of Africa. Heaviside’s are small and stocky with adults reaching a maximum length of 1.7m and weight of75 kg. The dolphin has a distinct black, grey and white body pattern, making it hard for it to be confused with any other dolphin found in the same waters. The head is cone shaped with a blunt beak. The dorsal fin is triangular in shape and centred in the middle of the back. The head and thorax are coloured light grey with darker patches around the eye. The dorsal fin,& fluke and dorsal cape are a dark grey to almost black with a band that extends forward from the dorsal fin to the blowhole. The underbelly is white, with bands that extend onto the lower rear of the body. Small white patches are located just behind the pectoral fins and a single white patch extends between these fins on the chest. Sexual dimorphism is minimal, however variation in the shape of the white patch covering the genital slit is distinct between genders. In males, the patch ends in a point, but in females widens out to cover the mammary slits.

Information on reproduction is limited for Heaviside’s dolphins, however they are thought to be comparable to Hector’s and Commerson’s dolphins. Females and males reach sexual maturity approximately between 5–9 years. Mating is thought to occur year-round, however individual females may only produce calves every 2–4 years. Gestation time is unknown. Maximum known lifespan is based on the oldest recorded individual at 26 years old. Levels of predation are unknown, however killer whales(Orcinus orca) are known predators and there is evidence of shark attack from body scars.
Heaviside’s have small home ranges of 50–80km as measured using satellite telemetry over 2–3 months and photographic resighting over up to 3 years.

 Some individuals have been resighted at the same location for up to 10 years. Prior to 2018, the “International Union for Conservation of Nature” International Union for Conservation of Nature (IUCN) listed the Heaviside’s as ‘Data Deficient’ however, as of 2017 the status was changed to ‘Near Threatened’, owing to improved knowledge on the species from multiple studies. Despite this, the overall population trend remains unknown, and there are many aspects of the species biology that remain to be studied. Heaviside’s dolphin is listed on Appendix II of the “Convention on the Conservation of Migratory Species of Wild Animals” Convention on the Conservation of Migratory Species of Wild Animals Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia. Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia. The Memorandum of Understanding was established in 2008 and aims to protect these species at a national, regional and global level.

Below here is a video of some of these dolphins, and below that is our usual list of articles on this species (we hope this number will increase in the near future).

Below this, we will add links for you to go and see these dolphins for yourself

Commerson Dolphin

Commison Dolphin

Commerson’s dolphin  (also known as  jacobita, skunk dolphin, piebald dolphin, panda dolphin, or tonina overa (in South America), is a small oceanic dolphin of the genus Cephalorhynchus. The dolphin takes its name from the  French naturalist Dr Philibert Commerson, who first described them in 1767 after sighting them in the Strait of Magellan. To the right of this is a map of the Primary subspecies, the secondary subspecies lives a large distance out into the Indian ocean.

There are two geographically-isolated but locally-common subspecies. The principal subspecies, C.c.commersonii, has sharply-delineated black-and-white patterning and is found around the tip of South America. The secondary subspecies, C.c.kerguelenensis, is larger than C.c.commersonii, has a less-sharply delineated dark and light grey patterning with a white ventral band, and is found around the Kerguelen Islands in the Indian Ocean.

Commerson’s dolphin is very active. It is often seen swimming rapidly on the surface and leaping from the water. It also spins and twists as it swims and may surf on breaking waves when very close to the shore. It will bow-ride and swim behind fast-moving boats. It is also known to swim upside-down, which is thought to improve the visibility of its prey.

This dolphin feeds on a mix of coastal and pelagic fish and squid. Those in the South American subpopulation supplement their diets with crustaceans Individuals have been recorded as entering the Santa Cruz River to forage there during low tide. They can be found in estuaries, especially during the breeding season.
The IUCN lists Commerson’s dolphin as Least Concern in its Red List of Threatened Species. The proximity of the dolphin to the shore makes accidental killing in Gillnet a common occurrence. The dolphin was killed for use as crab Bait (luring substance) by some Argentinian and Chilean fishermen in the 1970s and 1980s, but this practice has since been curtailed. The Commerson’s dolphin population of South America is listed on Appendix II of the “Convention on the Conservation of Migratory Species of Wild Animals” Convention on the Conservation of Migratory Species of Wild Animals. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.

There are a few of these dolphins in captivity.

Below is a video (there are clearer captive videos do have a look) below that will be a list of any stories on this species

Below that, I will add any links to people who can help you see these species in the wild.

Black Dolphin

Black Dolphin (Chilean)

The Chilean dolphin , also known as the black dolphin, is one of four dolphins in the genus Cephalorhynchus. The dolphin is found only off the coast of Chile; it is commonly referred to in the country as tonina. The Chilean dolphin is small at around 1.7 metres (5 ft 7 in) in length, with a blunt head., which means that it is regularly confused with a porpoise.

The population of the Chilean dolphin, perhaps one of the least studied of all cetaceans, is not known with certainty. There may be as many as a few thousand individuals, although at least one researcher, Steve Leatherwood, has suggested the population may be much lower.

The Chilean dolphin is listed on Appendix II Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. The total population is thought to be under 5000.

Below, you will first find a video on this species. Under this, you will find a list of any articles that have been written on this species (or any that will be written by the time you look). Below that, I will add any links that will help you see these animals in the wild.

White-beaked dolphin

White beaked dolphin

The white-beaked dolphin  is a marine mammal belonging 

to the family Delphinidae (oceanic dolphins) in the sub order Odontoceti (toothed whales). Their distribution is shown in the map.

The white-beaked dolphin is endemic to the cold temperate and subarctic waters of the North Atlantic Ocean, most commonly in seas less than 1,000 m (3,300 ft) deep. Due to the fact they are not fully adapted to Arctic conditions, they are more vulnerable to predators, most notably polar bears. Within this wider region, white-beaked dolphins are most commonly found in four locales: on the Labrador Shelf close to southwestern Greenland, around Iceland, off the northern and eastern coasts of Britain, and off the coast of Norway. In the Faroe Islands between Iceland and the United Kingdom the White-beaked dolphin is at risk of being hunted during drive catches of the long-finned pilot whales. They may also be incidentally trapped in the purse-sein and trawl nets of the area. There are no recognised subspecies.

The dolphin may easily be misidentified as the Atlantic white-sided dolphin, although the white-beaked is commonly found further north. The white-beaked dolphin is also typically larger, and does not have yellow streaks on its side.

Below is a video (no sound) of them filmed under water off the coast of the UK. Northern parts of the UK have populations, including Lyme bay and areas around the hebrides.

They are thought to number 100,000, so are listed as least concern.

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