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Changes of population trends and mortality patterns in response to the reintroduction of large predators: The case study of African ungulates

Large predators have been reintroduced to an increasing number of protected areas in South Africa. However, the conditions allowing both prey and predator populations to be sustained in enclosed areas are still unclear as there is a lack of understanding of the consequences of such reintroductions for ungulate population dynamics. Variation in lion numbers, two decades after their first release, offered a special opportunity to test the effects of predation pressure on the population dynamics of seven ungulate species in

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Long-term persistence of wildlife populations in a pastoral area

Facilitating coexistence between people and wildlife is a major conservation challenge in East Africa. Some conservation models aim to balance the needs of people and wildlife, but the effectiveness of these models is rarely assessed. Using a case-study approach, we assessed the ecological performance of a pastoral area in northern Tanzania (Manyara Ranch) and established a long-term wildlife population monitoring program (carried out intermittently from 2003 to 2008 and regularly from 2011 to 2019) embedded in a distance sampling framework.

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Population dynamics of the Maasai giraffe (Giraffa camelopardalis tippelskirchi) in Tarangire-Manyara Ecosystem

Demographic studies can show overall population performance, help understand population structure and recognize animal distribution and movement. In order to investigate the social structure of giraffes in the Tarangire-Manyara Ecosystem, data on population structure, sex ratios, age ratios and habitat preference were examined in three protected areas. These areas included Lake Manyara National Park, Manyara Ranch and Tarangire National Park. A total of 348 giraffes were sexed and aged in the three areas combined. Manyara Ranch had the largest maximum

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Early detection of declining populations using floor and ceiling models

1. Within Caughley’s (1994) declining population paradigm for conservation, we develop a realistic method of detecting population changes using floor and ceiling population models. 2. A theoretical framework for detecting declining populations is presented and applied to four ungulate species from Kruger National Park, South Africa. 3. Census data are fitted to a non-linear autoregressive population model. Based on this model two auxiliary models, called the floor and ceiling models, are derived. These models predict the upper and lower threshold

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Large-scale ruminant genome sequencing provides insights into their evolution and distinct traits

The ruminants are one of the most successful mammalian lineages, exhibiting morphological and habitat diversity and containing several key livestock species. To better understand their evolution, we generated and analyzed de novo assembled genomes of 44 ruminant species, representing all six Ruminantia families. We used these genomes to create a time-calibrated phylogeny to resolve topological controversies, overcoming the challenges of incomplete lineage sorting. Population dynamic analyses show that population declines commenced between 100,000 and 50,000 years ago, which is concomitant

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Ecology of the giraffe in Tsavo East National Park, Kenya

The decrease in woody vegetation in Tsavo National Park has probably had adverse effects on woodland-adapted herbivores, including the giraffe (Girafa camelopardalis). In an ecological study we attempted to assess this species’ density, habitat preference and utilization, and population dynamics, using mainly road strip counts and identification of individual animals. Population structure varied seasonally and locally, indicating differential distribution of sex/age classes. Records on individually known animals suggested an annual mortality rate of c. 10% for adult plus subadult animals.

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ENSO, rainfall and temperature influences on extreme population declines among African savanna ungulates

Climatic variation associated with the North Atlantic Oscillation (NAO) and El Nin˜o- Southern Oscillation (ENSO) has a widespread influence on the population dynamics of many organisms worldwide. While previous analyses have related the dynamics of northern ungulates to the NAO, there has been no comparable assessment for the species rich assemblages of tropical and subtropical Africa. Census records for 11 ungulate species in South Africa’s Kruger National Park over 1977–96 reveal severe population declines by seven species, which were inadequately

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Season of birth affects juvenile survival of giraffe

Variation in timing of reproduction and subsequent juvenile survival often plays an important role in population dynamics of temperate and boreal ungulates. Tropical ungulates often give birth year round, but survival effects of birth season for tropical ungulate species are unknown. We used a population of giraffe in the Tarangire Ecosystem of northern Tanzania, East Africa to determine whether calf survival varied by season of birth. Variation in juvenile survival according to season of birth was significant, with calves born

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All the eggs in one basket: A countrywide assessment of current and historical giraffe population distribution in Uganda

To design effective conservation and management strategies at the national scale, it is important to consider population trends across space and time. Here we assessed the near threatened Rothschild’s giraffe (Giraffa camelopardalis rothschildi) in Uganda. We applied individual-based photographic surveys to generate abundance estimates for all extant populations, using either mark-recapture estimates or complete enumeration, and reviewed available historical records to reconstruct the population history of giraffe in Uganda. Although anecdotal evidence from the early 20th century suggests giraffe were

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Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes

In long-distance migratory systems, local fluctuations in the predator–prey ratio can exhibit extreme variability within a single year depending upon the seasonal location of migratory species. Such systems offer an opportunity to empirically investigate cyclic population density effects on short-term food web interactions by taking advantage of the large seasonal shifts in migratory prey biomass. We utilized a large-mammal predator–prey savanna food web to evaluate support for hypotheses relating to the indirect effects of “apparent competition” and “apparent mutualism” from

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