Optimising the cost of roadkill surveys based on an analysis of carcass persistence.

Reliable estimates of wildlife mortality due to wildlife-vehicle collisions are key to understanding its impact on wildlife populations and developing strategies to prevent or reduce collisions. Standardised approaches for monitoring roadkill are needed to derive robust and unbiased estimates of mortality that are comparable across different study systems and ecological contexts. When designing surveys, there is a trade-off between survey frequency (and hence logistical effort and financial cost) and carcass detection. In this regard, carcass persistence (the period a carcass remains detectable before being removed by decomposition or scavengers) is important; the longer a carcass persists, the greater the likelihood it will be detected with lower survey effort by conducting more infrequent surveys. Using multi-taxon carcass data collected over a month of repeated driven surveys, combined with five covariates (species functional group, body weight, carcass position on road, carcass condition [either flattened or not after impact], and rainfall prior to each survey), we explored the drivers of carcass persistence with the overall aim of providing information to optimise the design of carcass surveys along linear infrastructure. Our methodological approach included a survival analysis to determine carcass persistence, linear regressions to test the effect of covariates, a subsampling analysis (using field data and a simulation exercise) to assess how the proportion of carcasses detected changes according to survey frequency, and an analysis to compare the costs of surveys based on study duration, transect length and survey frequency. Mean overall carcass persistence was 2.7 days and was significantly correlated with position on road and within-functional group body weight. There was no evidence for a significant effect of rainfall, while the effect of carcass condition was weakly non-significant. The proportion of carcasses detected decreased sharply when survey intervals were longer than three days. However, we showed that survey costs can be reduced by up to 80% by conducting non-daily surveys. Expanding on the call for a standardised methodology for roadkill surveys, we propose that carcass persistence be explicitly considered during survey design. By carefully considering the objectives of the survey and characteristics of the focal taxa, researchers can substantially reduce logistical costs. In addition, we developed an R Shiny web app that can be used by practitioners to compare survey costs across a variety of survey characteristics. This web app will allow practitioners to easily assess the trade-off between carcass detection and logistical effort.

Tracking data from nine free-roaming Cheetahs (Acinonyx jubatus) collared in the Thabazimbi area, Limpopo Province, South Africa.

BACKGROUND: In partnership with the University of Pretoria, the Endangered Wildlife Trust's Carnivore Conservation Programme collared six male and three female free-roaming Cheetahs (Acinonyx jubatus) in the Thabazimbi area in Limpopo Province, South Africa. This study was undertaken to determine the spatial ecology of free-roaming Cheetahs that occur outside of formal protected areas on private ranchland, where they frequently come into conflict with, and are sometimes killed by, private landowners. The data were collected between September 2003 and November 2008, resulting in a total of 3165 location points (65 points from VHF collars and 3100 from GPS collars) for nine individual Cheetahs. NEW INFORMATION: This dataset provides distribution information about this Vulnerable species occurring outside of protected areas within South Africa. The dataset has been published to the Global Biodiversity Information Facility (www.GBIF.org) and provides the largest dataset on Cheetahs thus far, and, although it is spatially limited to a relatively small region on the African continent, it is the first study of its kind within South Africa. Also of significance is that the fate of 6 of the 9 collared Cheetahs is known, all except one of which died of anthropogenic causes.

The African Crane Database (1978-2014): Records of three threatened crane species (Family: Gruidae) from southern and eastern Africa.

BACKGROUND: The International Crane Foundation (ICF) / Endangered Wildlife Trust's (EWT) African Crane Conservation Programme has recorded 26 403 crane sightings in its database from 1978 to 2014. This sightings collection is currently ongoing and records are continuously added to the database by the EWT field staff, ICF/EWT Partnership staff, various partner organizations and private individuals. The dataset has two peak collection periods: 1994-1996 and 2008-2012. The dataset collection spans five African countries: Kenya, Rwanda, South Africa, Uganda and Zambia; 98% of the data were collected in South Africa. Georeferencing of the dataset was verified before publication of the data. The dataset contains data on three African crane species: Blue Crane Anthropoides paradiseus, Grey Crowned Crane Balearica regulorum and Wattled Crane Bugeranus carunculatus. The Blue and Wattled Cranes are classified by the IUCN Red List of Threatened Species as Vulnerable and the Grey Crowned Crane as Endangered. NEW INFORMATION: This is the single most comprehensive dataset published on African Crane species that adds new information about the distribution of these three threatened species. We hope this will further aid conservation authorities to monitor and protect these species. The dataset continues to grow and especially to expand in geographic coverage into new countries in Africa and new sites within countries. The dataset can be freely accessed through the Global Biodiversity Information Facility data portal.

Renal function in Palestine sunbirds: elimination of excess water does not constrain energy intake.

Although the renal responses of birds to dehydration have received significant attention, the consequences of ingesting and processing large quantities of water have been less studied. Nectar-feeding birds must often deal with exceptionally high water intake rates in order to meet their high mass-specific energy demands. Birds that ingest large volumes of water may either eliminate excess water in the kidney or regulate the volume of water absorbed in the gastrointestinal tract. Because water absorption in the gastrointestinal tract of Palestine sunbirds (Nectarinia osea) decreases with increasing water ingestion rate, we predicted that glomerular filtration rate (GFR) in these birds would not be unusually high in spite of large ingested water loads. When feeding on dilute sucrose solutions, sunbirds ingested between 4 and 6 times their body mass in nectar per day, yet they were able to compensate for varying nectar energy density and increased thermoregulatory energy demands with no apparent difficulty. GFR was lower than predicted (1976.22+/-91.95 microl h(-1)), and was not exceptionally sensitive to water loading. Plasma glucose concentrations were high, and varied 1.8-fold between fasted (16.08+/- 0.75 mmol l(-1)) and fed (28.18+/-0.68 mmol l(-1)) sunbirds, but because GFR was low, glucose filtered load also remained relatively low. Essentially the entire glucose filtered load (98%) was recovered by the kidney. Renal fractional water reabsorption (FWR) decreased from 0.98 to 0.64 with increasing water intake. The ability of Palestine sunbirds to reduce the absorption of ingested water in the gastrointestinal tract may resolve the potential conflict between filtering a large excess of absorbed water in the kidney and simultaneously retaining filtered metabolites.

Ammonotely in a passerine nectarivore: the influence of renal and post-renal modification on nitrogenous waste product excretion.

Most aquatic vertebrates are ammonotelic, whereas terrestrial vertebrates are typically uricotelic or ureotelic. However, the principal form of nitrogenous waste product in the urine of an animal may vary, depending on environmental conditions. Anna's hummingbird (Calypte anna) was found to switch from uricotely at high ambient temperature (T(a)) to ammonotely at lower T(a), when energy demands and consequent nectar intake rates were high. In extension of this, we hypothesised that nectarivorous birds would switch from uricotely to ammonotely when water intake rates were high or when protein or salt intake rates were low. We examined the influence of water, electrolyte and protein intake and of T(a) on the excretion of ammonia, urea and urate (uric acid and its salts) in nectarivorous Palestine sunbirds (Nectarinia osea). The proportion of ammonia in ureteral urine and excreted fluid was not influenced by total water or salt intake or by T(a). Protein intake did not influence nitrogenous waste product concentrations in ureteral urine. However, when protein intake was reduced, the proportion of ammonia in excreted fluid was higher because of the reduced urate concentration. This reduction in urate concentration leads to 'apparent' ammonotely. We suggest that ammonotely may not be a unique feature of nectarivorous birds. It could occur in any species in which breakdown of urate in the hindgut allows the uric acid-nitrogen concentration in the excreta to fall below that of the ammonia-nitrogen concentration.

Digestion of nectar and insects by Palestine sunbirds.

In nectarivorous birds, specialization for feeding on nectar has led to a simple gut structure with high sugar digestive efficiencies and rapid gut passage rates. These features of the digestive system may make digestion of more complex, protein-rich food sources, such as pollen or insects, less efficient. In this light, we hypothesized that sugar metabolizability in nectarivorous Palestine sunbirds (Nectarinia osea) would be high, whereas nitrogen metabolizability would be lower than typically found for birds. We measured glucose and fructose apparent metabolizabilities (*MCs) and transit times (TTs) in eight Palestine sunbirds offered either a 10% or a 50% mixed sugar diet. *MC for glucose (99.9%+/-0.1%) was significantly greater than for fructose (99.6%+/-0.4%; ANOVA; P<0.001). TT for the 10% sugar diet (26.3+/-10.1 min) was significantly shorter than for the 50% sugar diet (47.0+/-7.8 min). We measured nitrogen true metabolizability (MC) and TT in Palestine sunbirds offered a daily fruit fly intake of either 40 or 200 flies. Nitrogen MC was not significantly different between diets, and average MC for both diets was 58.5%+/-8.5% (n=8). TT was not significantly different when birds ate 10 flies (50.1+/-13.6 min) than when they ate 50 flies (48.5+/-16.5 min). The high sugar *MC and relatively rapid TT of nectar in Palestine sunbirds are similar to those found for other nectarivorous species. Transit times of insect material are longer that those found in small insectivorous species. However, MCs of insect material are lower. Thus, even though sunbirds consume easily digestible soft-bodied insects, they are less efficient at extracting protein than nonnectarivores.