Modification of the third phase in the framework for vertebrate species persistence in urban mosaic environments.

Urbanisation is rapidly transforming natural landscapes with consequences for biodiversity. Little is documented on the response of African wildlife to urbanisation. We reviewed case studies of vertebrate species' responses to urbanisation in KwaZulu-Natal, South Africa to determine trends. Connected habitat mosaics of natural and anthropogenic green spaces are critical for urban wildlife persistence. We present a novel modification to the final of three phases of the framework described by Evans et al. (2010), which documents this sequence for vertebrate species persistence, based on the perspective of our research. Species in suburbia exhibit an initial phase where behavioural and ecological flexibility, life-history traits and phenotypic plasticity either contribute to their success, or they stay at low numbers. Where successful, the next phase is a rapid increase in populations and distribution; anthropogenic food resources and alternate breeding sites are effectively exploited. The modified third phase either continues to spread, plateau or decline.

Indigenous knowledge of South African bird and rangeland ecology is effective for informing conservation science.

South Africa's communal rangelands constitute ~25% of the country's land cover and are largely managed for livestock grazing. These habitats play an important role in rural livelihoods and cultural practices. Using semi-structured interviews, we documented indigenous local ecological knowledge (LEK) held by rural dwellers linked to natural resource utilisation, environmental health and cultural keystone indicator species (CKIS) in the grassland communities of southern KwaZulu-Natal, South Africa. Our main objective was to examine the ability for LEK to inform conservation management. We found that people who were heavily reliant on natural resources attained a higher LEK score, indicating a greater breadth of ecological knowledge, which in turn shaped their perceptions of environmental change. Community members confirmed the presence of conservation concern species within this area, highlighting the limitations of only using citizen science databases for conservation management, as their observations within these databases are biased towards major road routes and protected or urban areas. LEK can play an important role in identifying habitats crucial to species' persistence and delineating population trends over time. Our surveys highlighted the importance of the Southern Ground-hornbill Bucorvus leadbeateri as a CKIS that acts as an early warning system of changing weather, notably rain. However, LEK is context-specific, and some CKIS species such as the Southern Ground-hornbill have wide distribution ranges. Consequently, the cultural associations and implications differ based on local belief systems that are often defined by the language spoken and the community's geographical location. Our study demonstrated the importance of including indigenous LEK in conservation planning for threatened species and habitats and the importance of traditional family values responsible for transferring oral knowledge.

Digestive efficiencies of Cape white-eyes (Zosterops virens), red-winged starlings (Onychognathus morio) and speckled mousebirds (Colius striatus) fed varying concentrations of equicaloric glucose or sucrose artificial fruit diets.

Digestive physiology is important for understanding the feeding behaviour of organisms. Specifically, studies on the digestive physiology of frugivorous and nectarivorous birds are important for elucidating their preference patterns in the wild and the selective pressures they exert on fruit pulp and nectar. In this study, digesta transit times and digestive efficiencies of three species of birds, the Cape white-eyes (Zosterops virens), red-winged starlings (Onychognathus morio) and speckled mousebirds (Colius striatus) were investigated on equicaloric glucose or sucrose artificial fruit diets. Three concentrations, approximating the natural range of sugar concentrations in sugary, bird-dispersed fruits were used: low (6.6%), medium (12.4%) and high (22%). Digesta transit times of birds increased with an increase in concentration for all diets but were generally higher on glucose diets. Intake rates, on the other hand, decreased with an increase in sugar concentration. All species of birds failed to maintain a constant assimilated energy intake on glucose diets but mousebirds and white-eyes maintained it on sucrose diets. Apparent assimilation efficiencies of glucose diets for all species were comparable and typical of those found in other frugivorous birds. However, assimilation efficiencies for sucrose diets differed widely with red-winged starlings displaying very low assimilation efficiencies and as a consequence; they lost significant body mass on all sucrose diets. These results demonstrate the importance of digestive physiology in explaining fruit selection patterns in frugivorous birds and how a seemingly trivial physiological trait can have dire ecological consequences.

Effects of tannins on fruit selection in three southern African frugivorous birds.

Tannins are common secondary compounds in plant material and are known for their ability to bind to protein which reduces nitrogen availability in the diet. In fruits, these compounds are responsible for their astringency which is thought to result in reduced food intake. In this study, the repellent effects of tannins were examined in three species of frugivorous birds: red-winged starlings Onychognathus morio, speckled mousebirds Colius striatus and Cape white-eyes Zosterops virens. Birds were fed artificial fruit diets containing varying levels of tannins in paired choice tests with the amount of food eaten by birds used to determine preference. Red-winged starlings were attracted to the control diet, indifferent to the medium tannin diet and deterred by the high tannin diet whereas speckled mousebirds and Cape white-eyes were not deterred at all concentrations. The discrepancy in the results was attributed to differences in taste sensitivity, tolerance levels and detoxification mechanisms of secondary compounds between species. Because fruit selection and ultimately fruit removal rates affect plant community composition, the disparity in the results suggests that frugivorous birds do not contribute equally to plant community dynamics. However, plant secondary compounds in fruits are diverse and their effects are similarly diverse and there is potential that different groups of secondary compounds generate disparate effects. Similar studies on other types of secondary compounds may thus contribute towards a broader understanding of the role of secondary compounds in mediating fruit-frugivore interactions.

Seasonal thermoregulation in the burrowing parrot (Cyanoliseus patagonus).

Birds exposed to seasonal environments are faced with the problem of maintaining thermogenic homoeostasis. Previous studies have established that birds native to the Holarctic increase their Resting Metabolic Rate at different ambient temperatures (RMRTa) and Basal Metabolic Rate (BMR) in winter as an adaptation to cold temperature since winters are more severe, while their non-Holarctic counterparts generally decrease their winter BMR as an energy saving mechanism during unproductive and dry winter months. In this study, we examined seasonal thermoregulation in the burrowing parrot (Cyanoliseus patagonus), a colonial psittacine native to the Patagonian region of Argentina, a region with an unpredictable environment. We found significantly higher mass specific RMRTa and BMR in summer than in winter. Both summer and winter BMR of the species fell within the predicted 95% confident interval for a parrot of its size. Body mass was significantly higher in winter than in summer. The burrowing parrot had broad thermo-neutral zones in winter and summer. The circadian rhythm of core body temperature (Tb) of burrowing parrots was not affected by season, showing that this species regulated its Tb irrespective of season. These results suggest that the burrowing parrots' seasonal thermoregulatory responses represent that of energy conservation which is important in an unpredictable environment.