These relatively underpublicized national parks both extend westward from the Selous Game Reserve, but they are otherwise very different in character. The more conventional safari destination, gazetted in 1964, Mikumi is the country's fourth-largest national park, protecting some 3,260 sq. km (1,271 sq. miles) of open grassland and wooded slopes flanking the main highway through southern Tanzania, immediately east of the small junction town after which it is named. By contrast, the 1,915-sq.-km (747-sq.-mile) Udzungwa Mountains National Park, created in 1992, protects the forested northeastern block of Tanzania's most extensive mountain range, an area known for its immense biodiversity and wealth of endemic plant and animal species.
Wildlife moves freely across the common border between Mikumi and Selous, but the two reserves are mutually inaccessible by road. However, Mikumi is easily accessed from the Tanzam Highway, and though it is seldom marketed as a standalone safari destination, it is a place to break up the long drive between Dar es Salaam and Ruaha National Park. The main game-viewing circuit loops northwest of the main road, through the Mkata Floodplain, a landscape of swaying grass and isolated trees reminiscent of the Serengeti. The floodplain supports large numbers of elephant, giraffe, buffalo, zebra, wildebeest, eland, impala, waterbuck, reedbuck, warthog, and yellow baboon, as well as healthy populations of lion and spotted hyena. Occasional transient packs of African wild dog are seen, too, whereas patches of miombo woodland harbor the impressive greater kudu and sable antelope. Among the more visible of 400-plus recorded bird species are the handsome bateleur eagle, outsized ground hornbill, and colorful lilac-breasted roller.
Spanning altitudes of 245 to 2,780m (804-9,118 ft.), Udzungwa is the largest of the Eastern Arc Mountains, a series of a dozen crystalline ranges that rise from the coastal belt of Tanzania to support East Africa's most ancient and biologically diverse forests. Although three-quarters of Udzungwa's forest cover has been chopped down over the course of the past two millennia, around 2,720 sq. km (800 sq. miles) is still intact, most of it protected within the national park or adjoining forest reserves. The forest of Udzungwa is home to several endemics (species that occur nowhere else), including two monkeys, Uhehe red colobus and Sanje crested mangabey, and several birds, of which the Udzungwa forest partridge, discovered as recently as 1991, is the most remarkable. And this list of endemics is still growing: Recent discoveries include the Matunda dwarf galago, first described in 1996, and the world's largest species of elephant shrew, first photographed in 2005; the kipunji monkey was simultaneously discovered in a forest reserve in the western Udzungwa and on the more southerly Mount Rungwe area in 2004.
For all its ecological significance, Udzungwa remains a somewhat unsung gem. There are no roads within the national park, but a network of walking trails traverses the forested eastern slopes, mostly starting at the Mang'ula entrance gate. These include the self-guided Prince Bernhard Waterfall Trail, which leads to a small but pretty waterfall less than 1 mile from the entrance gate, and offers a good chance of sighting the endemic red colobus monkey and a variety of birds, including green-headed oriole. The guided Sanje Waterfall Trail is a 4-hour round-trip hike leading to a cascade that drops about 305m (1,000 ft.) over three stages into a pool where swimming is permitted. The longest hike is the Mwanihana Trail, which ascends to the second-highest point in the range and involves camping for 2 nights in areas that offer a good chance of spotting the endemic mangabey, the rare Abbott's duiker, and larger mammals such as elephant.