Implications of farmland expansion for species abundance, richness and mean body mass in African raptor communities

Shaw, Philip; Kibuule, Micheal; Nalwanga, Dianah; Kaphu, George; Opige, Michael; Pomeroy, Derek

doi:10.1016/j.biocon.2019.03.039

Cited by 9 publications

(11 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…African white‐backed vulture ERs in southern Tanzania were more than double those in Kenya in some parks (Virani et al., 2011). Although we considered only PAs, we expect even higher rates of decline outside these parks, as shown elsewhere in Africa (Pomeroy et al., 2014; Shaw et al., 2019; Virani et al., 2011). Our results demonstrate both significant declines and the importance of southern Tanzania for the conservation of African vultures, where greater efforts will be needed to mitigate the threat of poisoning.…”

Section: Discussionmentioning

confidence: 65%

“…Generally, the NPs have higher wildlife densities and, thus, were chosen as presumed areas of importance for vulture foraging and monitoring in the landscape. We focused on PAs (as for NPs) because higher rates of decline outside of PAs are already well described (Pomeroy et al., 2014; Shaw et al., 2019; Virani et al., 2011). In addition, for wide‐ranging species, such as African white‐backed vultures, it can be assumed that lower abundance and higher declines outside PAs than inside are partially explained by reductions in their use of these areas as they undergo habitat conversion and reductions in wildlife abundance.…”

Section: Methodsmentioning

confidence: 99%

“…We calculated recent ER as birds per 100 km from the last 3 years of study (2019)(2020)(2021) for comparison with other work. ERs for the 3 southern Tanzania NPs were compared with other savannah ecosystems in East Africa based on recent counts from across Kenya (Ogada et al, 2022) and Uganda (Shaw et al, 2019).…”

Section: Transect Analysesmentioning

confidence: 99%

See 2 more Smart Citations

Value of combining transect counts and telemetry data to determine short‐term population trends in a globally threatened species

Kendall

Bracebridge

Lynch

et al. 2023

Conservation Biology

View full text Add to dashboard Cite

In order to evaluate conservation interventions, it is necessary to obtain reliable population trends for short (<10 years) time scales. Telemetry can be used to estimate survival rates, and has become a common tool for assessing population trends, but can be limited by high costs, weight and technology constraints that limit duration of function and number of fixes, and can be biased to specific behavioral traits of tagged individuals. Encounter rates calculated from transects can be useful for assessing changes across multiple species, but can have large confidence intervals and can be affected by variation in survey conditions. Declines of African vultures, largely due to poisoning, have been well‐documented over the last several decades, but our understanding of more recent trends is lacking. We used two methods to assess population trends in three protected areas in southern Tanzania over 6–8 years: telemetry data primarily from White‐backed vultures to estimate survival rates, with corresponding estimated population trajectories based on population models, and transect counts for six scavenging raptors. Both methods suggest significant declines for White‐backed vultures in Ruaha and Nyerere National Parks, while only telemetry estimates suggested significant declines in Katavi National Park. Encounter rates calculated from transects also showed declines in Nyerere National Park for Lappet‐faced vultures and Bateleurs and in Ruaha National Park for White‐headed vultures. Mortalities recorded and inferred from telemetry suggest that poisoning is prevalent while highlighting the challenges of determining cause of death when working across large landscapes. Despite these declines, southern Tanzania remains an important stronghold for African vultures with higher current encounter rates than elsewhere in East Africa. However, preventing further declines will heavily depend on the ability to mitigate the threat of poisoning. This study demonstrates the value of using multiple techniques when attempting to understand population trends over short time periods.This article is protected by copyright. All rights reserved

show abstract

Section: Discussionmentioning

confidence: 65%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Value of combining transect counts and telemetry data to determine short‐term population trends in a globally threatened species

Kendall

Bracebridge

Lynch

et al. 2023

Conservation Biology

View full text Add to dashboard Cite

show abstract

“…Of growing concern is that these trends are mirrored in many other parts of southern and eastern Africa (e.g. Kalema et al 2015, Shaw et al 2019, Tripathi et al 2021), where they are mainly attributed to human population growth and the coincidental spread of agriculture, rural development, and fuelwood harvesting, and linked with accelerating rates of loss of dense woodland habitat. Hence, the destruction and degradation of woodland is a documented phenomenon, both locally and across the continent, indicating that the future prognosis for the eastern escarpment Taita Falcon population, and for the species globally, may be bleak without prompt and effective conservation management.…”

Section: Discussionmentioning

confidence: 99%

Drivers of scarcity in the globally threatened Taita Falcon Falco fasciinucha: competition and habitat quality in the eastern escarpment region of South Africa

Jenkins¹,

Zyl²,

Colyn

et al. 2023

Bird Conservation International

View full text Add to dashboard Cite

Summary The Taita Falcon Falco fasciinucha is known to occur and breed at only a few locations in eastern and southern Africa and is currently listed as globally “Vulnerable” and “Critically Endangered” in South Africa. An accurate estimation of its conservation status is however hampered by a lack of data and understanding of the species’ habitat requirements and competitive interactions with congeners. Our aim was to address some of these knowledge gaps. We conducted cliff-nesting raptor surveys across a substantial area of the Mpumalanga/Limpopo escarpment in north-eastern South Africa and modelled habitat suitability for nesting Taita Falcons in relation to the proximity of conspecifics and a community of five other sympatric cliff-nesting raptor species, and in relation to a suite of biotic and abiotic environmental variables. Results suggested the location of Taita Falcon nest sites was negatively associated with distance to the nearest pair of conspecifics and the nearest pair of Lanner Falcons Falco biarmicus, and positively associated with tracts of intact, unfragmented forest and woodland around the base of the cliffs. Our results indicated that Taita Falcon and Lanner Falcon appeared to be responding in opposite ways to a directional change in environmental conditions. This response appeared to be detrimental to Taita Falcon and beneficial to Lanner Falcon. Furthermore, the degradation and destruction of Afrotropical woodland and forest is a documented and ongoing reality, both locally and across much of the Taita Falcon’s global distribution. We argue that our findings are sufficient to justify uplisting Taita Falcon to globally “Endangered”.

show abstract

“…The overall decline among seed-eating passerines in savannah-like habitats, as quantified by Zwarts et al (2018, 2023a, 2023b, 2023d), has resulted in a substantial decline in food supply of bird-eating raptors. On the other hand, the conversion of savannah into farmland and floodplains into rice fields will, temporarily at least, favour rodent-eating raptors (Anadon et al 2010, Buij et al 2012, 2013, Augiron et al 2015, Shaw et al 2019). The overall effect of changing landscapes on raptors in the sub-Sahara, especially on small and medium-sized species, is presently an enigma but in the long run augurs large changes (Amar et al 2018).…”

Section: Discussionmentioning

confidence: 99%

Distribution and Relative Density of Raptors in the Sub-Sahara during the Dry Season

Bijlsma¹,

Kamp²,

Zwarts³

2023

Ardea

View full text Add to dashboard Cite

The sub-Sahara between the Atlantic Ocean and Red Sea and between 5°N (Guinean vegetation zone) and 20°N (southern Sahara) was visited on 466 days during 15 dry seasons (late September – early March) in 1996–2019. Using a combination of field methods, ranging from road counts to surveys of single sites (non-random and random-stratified), a total of 22,696 raptors of 62 species were identified. These were allocated to 1° latitude-longitude grid cells. Palearctic migrants accounted for 13% of the total. Two Afrotropical raptors were by far the most common, Yellow-billed Kite Milvus aegyptius (46%) and Hooded Vulture Necrosyrtes monachus (25%). Diversity and density were lowest in the arid and semi-arid zones but increased with increasing annual rainfall and vegetation cover. Palearctic migrants almost exclusively occupied the driest zones (100–500 mm rainfall per year), African raptors were commonest in the more humid zones. Migrants were concentrated in the western and eastern sections of the sub-Sahara, in longitudinal agreement with the main crossing points on either side of the Mediterranean for the large majority of Palearctic migrants. Comparatively few migrants were encountered in the central Sahel (Mali-Niger-Chad), suggesting that most Palearctic raptors remained either in West or in East Africa upon entering the continent. Even harriers Circus spp., known to cross the full width of the Mediterranean Sea, showed a distinct East Africa bias in their distribution. Afrotropical raptors were more evenly distributed across the width of the sub-Sahara within the 100–1000-mm rainfall zone.

show abstract

Implications of farmland expansion for species abundance, richness and mean body mass in African raptor communities

Cited by 9 publications

References 49 publications

Value of combining transect counts and telemetry data to determine short‐term population trends in a globally threatened species

Value of combining transect counts and telemetry data to determine short‐term population trends in a globally threatened species

Drivers of scarcity in the globally threatened Taita Falcon Falco fasciinucha: competition and habitat quality in the eastern escarpment region of South Africa

Distribution and Relative Density of Raptors in the Sub-Sahara during the Dry Season

Contact Info

Product

Resources

About