Thursday, 31 December 2020
Wednesday, 30 December 2020
Sunday, 27 December 2020
Saturday, 26 December 2020
Thursday, 24 December 2020
Wednesday, 23 December 2020
18-4-2018 CHOBE NAT PARK, BOTSWANA - BLACK HEADED HERON (Ardea melanocephala)
The black-headed heron, Ardea melanocephala, is a stately wading bird from the heron family Ardeidae. It stands at an impressive 85 cm in height, with a wingspan stretching to 150 cm. Its plumage is predominantly grey, with a darker shade above and a paler grey below. The bird is named for its striking black head, which contrasts with its grey body. A powerful dusky bill completes its commanding appearance.
When identifying the black-headed heron, look for its large size, nearly matching that of the grey heron. Its black head and neck, along with the grey body, are key distinguishing features. In flight, observe the slow wingbeats and the retracted neck, a common trait among herons. The white underwing coverts are particularly noticeable when the bird is airborne.
This heron is commonly found in a variety of wetland habitats throughout sub-Saharan Africa and Madagascar. It is comfortable in both shallow water and dry grasslands.
The black-headed heron is widespread across much of sub-Saharan Africa and Madagascar. It is mainly a resident species, though some individuals from West Africa may migrate northward during the rainy season.
The black-headed heron exhibits typical heron behavior, often seen feeding in shallow waters or stalking prey in grasslands. It is known to stand motionless, waiting for prey, or to slowly stalk its victim with stealth and precision.
The vocalizations of the black-headed heron include a distinctive loud croaking, often heard during dusk at heronries.
Breeding typically occurs in the wet season. The black-headed heron nests in colonies, which can be found in trees, reedbeds, or even on cliffs. It constructs a bulky stick nest and lays a clutch of 2 to 4 eggs.
The grey heron is the species most similar in appearance to the black-headed heron, but it can be differentiated by its size and coloration, particularly the grey heron's lack of a black head.
A versatile predator, the black-headed heron feeds on a diet that includes fish, frogs, large insects, small mammals, and birds. It employs both passive and active hunting strategies, either spearing its prey with its sharp bill or stalking it on land.
19-4-2018 NXABEGA LODGE OKAVANGO DELTA, BOTSWANA - TSESSEBE (Damaliscus lunatus)
The most important aggressive display of territorial dominance is in the horning of the ground. Another far more curious form of territory marking is through the anointing of their foreheads and horns with secretions from glands near their eyes. Tsessebe accomplish this by inserting grass stems into their preorbital glands to coat them with secretion, then waving it around, letting the secretions fall onto their heads and horns. This process is not as commonly seen as ground-horning, nor is its purpose as well known.
Several of their behaviors strike scientists as peculiar. One such behavior is the habit of sleeping tsessebe to rest their mouths on the ground with their horns sticking straight up into the air. Male tsessebe has also been observed standing in parallel ranks with their eyes closed, bobbing their heads back and forth. These habits are peculiar because scientists have yet to find a proper explanation for their purposes or functions.
Tsessebe are primarily grazing herbivores in grasslands, open plains, and lightly wooded savannas, but they are also found in rolling uplands and very rarely in flat plains below 1500 m above sea level. Tsessebe found in the Serengeti usually feed in the morning between 8:00 and 9:00 am and in the afternoon after 4:00 pm. The periods before and after feeding are spent resting and digesting or watering during dry seasons. Tsessebe can travel up to 5 km to reach a viable water source. To avoid encounters with territorial males or females, tsessebe usually travel along territorial borders, though it leaves them open to attacks by lions and leopards.
Tsessebe reproduce at a rate of one calf per year per mating couple. Calves reach sexual maturity in two to three and half years. After mating, the gestation period of a tsessebe cow lasts seven months. The rut, or period when males start competing for females, starts in mid-February and stretches through March. The female estrous cycle is shorter, but happens in this time.
The breeding process starts with the development of a lek. Leks are established by the congregation of adult males in an area that females visit only for mating. Lekking is of particular interest since the female choice of a mate in the lek area is independent of any direct male influence. Several options are available to explain how females choose a mate, but the most interesting is in the way the male's group in the middle of a lek.
The grouping of males can appeal to females for several reasons. First, groups of males can protect from predators. Secondly, if males group in an area with a low food supply, it prevents competition between males and females for resources. Finally, the grouping of males provides females with a wider variety of mates to choose from, as they are all located in one central area.[13] Dominant males occupy the center of the leks, so females are more likely to mate at the center than at the periphery of the lek.
Subscribe to:
Posts (Atom)