Alan Tk Lee

Endemic birds of the Fynbos biome: a conservation assessment and impacts of climate change

The South African Fynbos biome, a global biodiversity hotspot with high endemism and species richness, has six endemic bird species. These are important not only intrinsically, but also for ecological functioning and as flagships for South Africa’s economically valuable avitourism sector. Little is known about population sizes or realised distribution ranges of these six species, but projected range modelling based on occurrence from the South African Bird Atlas Project (SABAP) has suggested these species are vulnerable to climate change. We estimate global population sizes for these six endemics based on densities calculated from two intensive biome-wide point count surveys in 2012. We modelled regions of suitable climatic space, from which we established that mean annual temperature and the temperature of the warmest quarter of the year appear to limit Cape Rock-jumper Chaetops frenatus and Protea Canary Serinus leucopterus ranges. Both species have seen an apparent > 30% decrease in range and reporting rates (a proxy for abundance) in the twenty years between SABAP atlas periods (1987–1991 and 2007–ongoing). The Cape Rock-jumper result is unexpected: encounter rates are higher in shorter vegetation, dry slopes and habitats with more recent occurrence of fire – all proxies for proximate causes of climate change on the Fynbos. Although coastal plains are highly transformed, mountain Fynbos is the best protected of all the world’s Mediterranean-climate habitats, with relatively little anthropogenic land transformation. Long term weather datasets from the Fynbos demonstrate significant warming since 1960. We conclude from these lines of evidence that these decreases are consistent with the loss of suitable climate space and inability of these species to adjust physiologically to increasing temperatures.

Population metrics for fynbos birds, South Africa: densities, and detection and capture rates from a Mediterranean-type ecosystem §

Estimates of bird numbers through quantification of density and range sizes are necessary for decisions regarding conservation status, yet counts of birds are often confounded by uncertainty of detection. The status of the endemic birds of the Fynbos biome is of interest due to their conservation value in a global biodiversity hotspot, the ecological services they provide, and their importance for the avitourism industry. We conducted an extensive repeated point-count survey across the Fynbos biome, South Africa, to determine probability of detection and covariates of site occupancy for 27 bird species. Detection of most species was influenced by time of day, temperature or vegetation height. Important covariates influencing site occupancy were vegetation height, altitude, time since fire and habitat type. Site occupancy for four fynbos-endemic species was positively associated with increasing altitude. We further conducted point counts and mist-netting in eastern regions of the Fynbos biome to calculate local density and standardised capture rates. A linear regression analysis showed that capture rates were a function of bird densities, but that several species were captured at higher rates than expected, notably nectarivorous species. During mist-netting a relative abundance count was conducted. We expected deviation of the fit of the regression of capture rates on relative abundance to correlate with detection probability, because we expect this index to underestimate skulking and cryptic species, but there was no correlation. Estimated species richness indices were highest for the biome-wide survey, and lowest for mist-netting due to the body size limit imposed by the capture technique. Overall, we showed that point counts are an effective method for surveying birds in the fynbos and that mist-netting can be used to create an index of relative abundance for smaller species, but can be significantly affected by net placement.

Aspects of the ecology and morphology of the protea seedeater, Crithagra leucopterus, a little-known Fynbos endemic

The protea seedeater, Crithagra leucopterus, is one of six passerine birds endemic to the Fynbos Biome, South Africa. It is the least known of these, and there is very little information on breeding and habitat use. Through nest observations and a bird ringing scheme in the eastern sections of the Fynbos, we provide updated information on habitat use, breeding and population biometrics. We document changes in capture rates for a suite of birds in relation to a fire event and use of burnt and unburnt sites within Blue Hill Nature Reserve, South Africa. Protea seedeaters were recorded nesting in mature Fynbos, but feeding in recently burnt Fynbos on freshly released protea seeds, suggesting the species benefits from small-scale burns that create a landscape of mixed veld ages. Protea seedeaters weighed less and had shorter wings compared to those of the western Fynbos. Further habitat-use and life-history information on protea seedeaters is needed to help guide conservation management plans, especially in the light of changing fire regimes in the Fynbos.

How well do bird atlas reporting rates reflect bird densities? Correlates of detection from the Fynbos biome, South Africa, with applications for population estimation

Relationships between true population densities and reporting indices from atlas data are important for the calculation of population sizes, though these relationships are remarkably little-known and likely confounded by issues of detection. We examine issues of detection for a single-observer point-count survey across the Fynbos biome in South Africa. We created an index of relative abundance comparable to atlas reporting rate and calculated detection coefficients for each species. We explore various models that explain relative abundance as a function of detection covariates, e.g. mass, colour, group size, vocal behaviour and density. Density was consistently included across models and the best predictor when used alone in a validation exercise. We then calculated mean reporting rates for the citizen science South African Bird Atlas Project2 (SABAP2). A model of species’ reporting rates as determined by density for this set of birds suggested the correlation between atlas reporting rates and density estimates was weak, with species capable of using modified habitats exhibiting higher reporting rates than expected from the density estimates. There was a positive correlation between bird density and reporting rates corrected for by species mass. We used this relationship to calculate densities for the Fynbos bird species and compare results to published data.

Estimating conservation metrics from atlas data: the case of southern African endemic birds

Journal: Bird Conservation International Manuscript ID BCI-MP-2015-0118.R1 Manuscript Type: Main Paper Date Submitted by the Author: 25-Apr-2016 Complete List of Authors: Lee, Alan; Percy FitzPatrick Institute of African Ornithology, Biological Sciences Barnard, Phoebe; South African National Biodiversity Institute, Climate Change Adaptation Division Altwegg, Res; University of Cape Town, SEEC

Habitat variables associated with encounters of Hottentot Buttonquail Turnix hottentottus during flush surveys across the Fynbos biome

The Hottentot Buttonquail Turnix hottentotus is an endangered terrestrial turnicid and is endemic to the Fynbos biome, South Africa. Due to its secretive nature and apparent rarity almost nothing is known about the species, but its range has been subject to anthropogenic modification, invasion by alien plant species and is vulnerable to climate change. To model covariates associated with the presence of Hottentot Buttonquail we undertook flush surveys across the Fynbos biome, covering 275 km. Habitat variables at encounter sites were recorded in vegetation plots, as well as locations without encounters. There was a critical number of observers needed during a flush survey in order to account for buttonquail presence, with no encounters with less than five participants. After accounting for this, we found probability of encounters decreased with increasing time-since-fire. Probability of encounters were also negatively associated with increasing percentage grass and other vegetation cover. We also found no association between percentage cover of Restionaceae plants and encounter probability, considered previously to be the best indicator of Hottentot Buttonquail presence. This information will be of use to those interested in managing habitat for this species and should inform future conservation efforts.

Urbanization, climate and ecological stress indicators in an endemic nectarivore, the Cape Sugarbird

AbstractStress, as a temporary defense mechanism against specific stimuli, can place a bird in a state in which growth rates and resistance to diseases are diminished. The Cape Sugarbird Promerops cafer is an endemic specialist of the Cape Floristic Region (CFR) of South Africa that may be threatened by urbanization and climate change. Ecological stress due to urbanization and climate may result in disease and morphological abnormalities. We investigated the correlation between urbanization and climate and four ecological stress indicators (tarsal disease, fluctuating asymmetry, body condition and feather fault bars) in 1375 Cape Sugarbirds from 14 sites across the CFR. Sugarbirds at sites with warmer climates had a higher incidence of tarsal disease and fault bars. Birds closer to urban settlements had higher levels of fluctuating asymmetry and fault bars in feathers. There were no clear correlations among stress indicators. Cape Sugarbirds are subject to multiple stressors, and adequate monitoring of population health will require assessment of multiple rather than single stress responses.ZusammenfassungVerstädterung, Klima und ökologische Stressanzeiger bei einem endemischen Nektarfresser, dem Kaphonigfresser Stress, als vorübergehender Verteidigungsmechanismus gegen spezifische Reize, kann einen Vogel in einen Zustand versetzen, in dem Wachstumsraten und Resistenz gegen Krankheiten vermindert sind. Der Kaphonigfresser Promerops cafer ist ein endemischer Spezialist der Region Cape Floral (CFR) in Südafrika, der von Verstädterung und Klimaveränderung bedroht sein dürfte. Ökologischer Stress aufgrund von Verstädterung und Klima kann zu Krankheiten und morphologischen Anomalien führen. Wir haben den Zusammenhang zwischen Verstädterung und Klima und vier ökologischen Stressanzeigern (Tarsuskrankheit, fluktuierende Asymmetrie, Körperkondition und Hungerstreifen in den Federn) bei 1375 Kaphonigfressern an 14 Standorten quer durch die CFR untersucht. Kaphonigfresser an Standorten mit wärmerem Klima wiesen häufiger Tarsuskrankheiten und Hungerstreifen auf, Vögel aus der Nähe urbaner Siedlungen häufiger fluktuierende Asymmetrie und Hungerstreifen. Es gab keine deutlichen Korrelationen zwischen den Stressanzeigern. Kaphonigfresser sind vielfachen Stressfaktoren ausgesetzt, und um die Gesundheit von Populationen adäquat zu überwachen, ist es notwendig, vielfache und nicht nur einzelne Stressantworten zu bewerten.

Comparison of physiological responses to high temperatures in juvenile and adult Cape Rockjumpers Chaetops frenatus

Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.

Why Birds Matter: Avian Ecological Function and Ecosystem Services

(2018). Why Birds Matter: Avian Ecological Function and Ecosystem Services. Ostrich: Vol. 89, No. 2, pp. 203-204.