Peter Apps

Peter Apps
Botswana Predator Conservation

Ph. D. Zoology

About

69
Publications
73,828
Reads
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977
Citations
Introduction
New ideas, new approaches and new methods are my strengths. My research background is a combination of zoology and analytical chemistry. I have a B.A., M. Sc. and Ph. D. in Zoology and 35 years experience pushing the limits of gas chromatography and mass spectrometry to detect and identify trace levels of organic volatiles in complex mixtures. My combined zoological and chemical expertise bear fruit in groundbreaking research into how mammals use chemicals to communicate.
Additional affiliations
June 2008 - October 2017
Independent Researcher
Position
  • Senior Researcher
April 2008 - present
Botswana Predator Conservation Trust
Position
  • Senior Researcher
Description
  • I push the limits of GC-MS to identify the active constituents of endangered African Wild Dog chemical messages, aiming to produce artificial scent mark boundaries that will keep the Wild Dogs inside protected wildlife areas
February 2005 - March 2008
National Metrology Institute of South Africa
Position
  • Research Metrologist
Description
  • Metrology establishes the highest standards of measurement science. I focussed on GC-MS of pesticides and contaminants, precision headspace sampling of aqueous ethanol, bias in solvent measurement, and FIDs as primary measurements of amount of substance.

Publications

Publications (69)
Article
Full-text available
Covering: 1950 to 2015We compiled a data set of the compounds that terrestrial vertebrates (amniotes) use to send chemical signals, and searched for relationships between signal compound properties and signal function. Overall, relationships were scarce and formed only small-scale patterns. Terrestrial vertebrate signalling compounds are invariably...
Article
The felid-specific urinary odour compound 3-mercapto-3-methylbutanol and its precursors have been found in several felid species in captivity, but its presence in wild felids has not previously been investigated. We analysed the naturally deposited scent marks from three species of wild, free-ranging big cats in Northern Botswana and found 3-mercap...
Article
Full-text available
The precise determination of traces of organic volatiles is particularly challenging in semiochemistry and clinical chemistry, where specimen sizes are intrinsically limited and amounts of trace components correspondingly very small. This demands a sampling technique that is fully compatible with the ability of capillary columns and gas chromatogra...
Article
Full-text available
Chemical communication via olfactory semiochemicals plays a central role in the social behaviour and reproduction of mammals, but even after four decades of research, only a few mammal semiochemicals have been chemically characterized. Expectations that mammal chemical signals are coded by quantitative relationships among multiple components have p...
Article
Full-text available
Gas chromatography/mass spectrometry was used to identify 103 organic compounds from urine, feces, anal glands, and preputial glands of free-ranging African wild dogs, Lycaon pictus. Aliphatic acids were the dominant class of compound in all materials. In addition to aliphatic acids, urine contained dimethyl sulfone, 1,3-propanediol, benzoic acid,...
Article
Full-text available
Understanding the use of space by endangered African wild dogs (Lycaon pictus) can contribute to their conservation because persecution by livestock farmers is a major cause of mortality when wild dogs range outside protected wildlife areas. Scent-marking is likely to be a key mechanism by which African wild dog packs organise their mutual use of s...
Article
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A technique for counting small populations of recognisable animals as an alternative to mark recapture. It should work well with camera trap images.
Article
Full-text available
en Camera traps are now widely used to produce the data that inform critical, large‐scale conservation strategies, but insufficient attention has been paid to evaluating or validating their performance. A realistic, reproducible and rigorous test of camera trap performance has been developed, using a real animal target moving in different direction...
Article
Full-text available
Camera traps are very widely used to monitor the presence of animals and record their behaviour. Setting them up properly enhances their performance and data yield. The paper describes how camera traps work and gives basic advice on camera selection, setting up camera traps for various purposes, protecting them from animals, keeping them working an...
Article
Full-text available
Camera traps in Wildlife Management Area NG33 to the east of the Okavango Delta in northern Botswana captured videos of groups of ten and 11 Honey Badgers Mellivora capensis travelling close together. These group sizes are close to the maximum ever recorded, and double the previous maximum reported from southern Africa. How and why these large grou...
Article
Full-text available
Aggressive encounters may have important life history consequences due to the potential for injury and death, disease transmission, dispersal opportunities or exclusion from key areas of the home range. Despite this, little is known of their detailed dynamics, mainly due to the difficulties of directly observing encounters in detail. Here, we descr...
Article
Full-text available
The scent of 3-mercapto-3-methylbutanol (3-M-3-MB), a volatile component of leopard (Panthera pardus) and domestic cat (Felis silvestris catus) urine, released at about 10 ng/s from slow-release dispensers, elicited scent-marking from African civet (Civettictis civetta), small-spotted genet (Genetta genetta) and slender mongoose (Galerella sanguine...
Chapter
Full-text available
Identifying specific signaling components within complex mixtures is a common problem in semiochemistry. Both glandular secretions and excretory products contain components of semiochemical importance, but identifying these signals is problematic because they are usually parts of mixtures with several 100 components, of which only a subset may be i...
Chapter
Mammal odors (in the broad sense) are notorious for chemical complexity and small quantities of individual components. No single chromatographic separation can resolve all the components, and so some of them are partially or completely obscured by others. I have tested how useful deconvolution (AnalyzerPro, SpectralWorks; http:// www. spectralworks...
Article
Full-text available
Tandem marking occurs when both members of a pair scent-mark the same location in quick succession. This widespread behaviour, common in canids and monogamous antelopes, is generally believed to be involved in pair bond formation and advertisement. Despite their potential utility in determining tandem mark function, observations of individual contr...
Article
Full-text available
Scent‐marking is common in mammals, but where signals are carried by urine and faeces, distinguishing between scent‐marking and mere elimination is problematic. To do so, we documented behaviours and context variables associated with urination and defecation in free‐ranging endangered African wild dogs (Lycaon pictus) and tested whether these were...
Chapter
Scent marks can potentially be used to manage the movement patterns of free-ranging mammals. We are investigating the possibility that using synthetic scent marks to create artificial range boundaries will help to keep African wild dogs (Lycaon pictus) inside the safety of wildlife conservation areas. For this we need to produce synthetic scent mar...
Article
A wide variety of samples that can be analysed by gas chromatography do not lend themselves to the usual preparation of solvent extracts for split-splitless injections, and are best handled by purge and trap or equilibrium headspace sampling. A cryo-focussing, flow switching gas chromatography inlet system that handles different types of sample wit...
Article
Full-text available
Context. Conflict between large carnivores and livestock outside the boundaries of wildlife areas frequently results in losses to both livestock and predator populations. The endangered African wild dog (Lycaon pictus Temminck, 1820) is wide ranging and unrestricted by conventional fences, thereby posing a major challenge to conservation managers....
Article
Full-text available
A simple low-cost cannula assembly that extends the range of applications of standard split–splitless gas chromatography inlets has been constructed and applied in the laboratory. With no other modifications to the inlet, it allows true on-column injections with thin needles, and the use of fused-silica transfer lines and special devices, such as w...
Article
Full-text available
Evaporation losses of organic solvents used to dissolve reference solutions and samples lead directly to errors in the measurement Evaporation losses of organic solvents used to dissolve reference solutions and samples lead directly to errors in the measurement of amount of substance. This is due to changes in the mass fraction composition and the...
Article
High-performance liquid chromatography (HPLC)-UV and HPLC-Mass Spectrometry (MS) methods were developed for the quantitative analysis of the family of Hoodia gordonii steroid glycosides with appetite suppressing properties in dried plant material, in purified and enriched extracts and in various prototype food-products fortified with H. gordonii ex...
Article
Full-text available
The ability of two strains of Trichoderma, isolated from food, to produce the Volatile Organic Compounds 1,3-pentadiene and styrene was investigated. One of the strains had been implicated in a case of food spoilage involving the production of both compounds. In vitro in potato dextrose broth, the strains produced both 1,3-pentadiene and styrene wi...
Article
Full-text available
Natural materials are so complex that no single column can separate all of the components. Heart cutting 2-D GC (GC-GC) using a Deans switch provides maximum separation, but the requisite gas flow configurations have earned a reputation for being fiddly and time consuming to set up and tune, unless electronic gas controls and costly software are em...
Article
Full-text available
Continuous liquid-liquid extraction is a versatile, reliable and robust sample preparation technique, but there is a tendency for the solvent to make channels through the sample, causing uneven and incomplete extraction. A simple, cheap magnetic stirrer that prevents channelling improves extraction efficiency by between 2.8 and 17.6 times.
Article
Full-text available
South Africa's wildlife reserves are a major tourist attraction and source of employment. The reserves have many of Africa's large wild mammals; however, attacks by these animals pose a risk not only to tourists but also to workers on the reserves. Commercial press records covering all South African newspapers were reviewed for a 10-year period to...
Article
Milk samples were taken daily or twice weekly, and blood samples twice weekly, from six clinically healthy dairy cows. Acetone concentration was determined by a new headspace gas-chromatographic method that proved to be suitable in terms of practically, sensitivity and precision. The concentration of acetone in milk was closely correlated with that...
Article
Full-text available
To investigate the effects on milk fatty acid composition of recombinant bovine somatotropin (rBST) administered under South African conditions, 26 dairy cows were paired into two groups 84-112 days after calving. At two-weekly intervals the cows in the experimental group were injected with 500 mg of rBST in a slow-release formulation , while cows...
Article
A rapid, precise method has been developed for the determination of the fatty acid profile of small samples of milk fat. Lipids are extracted from milk with n-hexane, triglycerides are trans-esterified with sodium methoxide, and free fatty acids are esterified with methanolic hydrochloric acid. The methyl esters are separated on a narrow-bore, 5% p...
Article
An automated headspace gas-chromatographic method has been developed for the determination of acetone in the milk, blood and urine of dairy cows. Five ml samples were saturated with 2 g of sodium chloride and equilibrated for 30 min at 90 degrees C in a Hewlett-Packard HP 19395 A automatic headspace sampler. The headspace volatiles were transferred...
Article
The standard configuration split ratio of 20-40:1 reduces analytical sensitivity because most of the headspace volatiles are vented through the splitter rather than passing to the column. For an investigation of the clinical significance of the headspace volatiles of cows' milk an increase in sensitivity without a reduction in resolution or sample...
Article
Full-text available
Whole-body volatiles from males of the cryptic multimammate mouse speciesMastomys natalensis andM. coucha were analyzed by dynamic solvent effect sampling and capillary gas chromatography. One compound, 3-nonene-2-one, was always present, sometimes as the major component, in volatiles fromM. coucha and absent, or present only at low levels, in vola...
Article
The quantitative precision of dynamic solvent-effect sampling from solvent specimens is reported. For sub-nanogram amounts of a range of solutes at a concetration of 5:109 the coefficients of variations of peak areas, peak percentage areas and peak-area ratios are consistently below 10%. The dynamic solvent effect allows high-precision sampling of...
Article
The analysis of organic air pollutants using gas chromatography—mass spectrometry (GC‐MS) invariably involves some form of preconcentration of the sample which can substantially decrease the precision of the analysis. A relatively new sampling technique—solute focusing using the dynamic solvent effect—has been investigated for analysing organic air...
Article
Full-text available
1.1. The defensive secretion of two species of Traumastella, a primitive group in the Pentatomoidea, were analysed by dynamic solvent effect sampling, gas-liquid chromatography and mass spectrometry.2.2. Twenty-one components were recognized in the secretion of T. namaquensis and nineteen in that of T. elizabethae.3.3. Sixteen components were ident...
Article
In capillary gas chromatography static and dynamic solvent effect inlets provide quantitatively precise methods of sample introduction of solutes which fulfill the conditions for solute focussing. Equations are derived for the conditions for focussing on static and dynamic films. In the case of a static film a solute will be focussed if the sum of...
Article
Full-text available
Volatile constituents of the anal gland secretion and of scent marks of the aardwolf were identified using dynamic solvent effect sampling, capillary gas-liquid chromatography, and mass spectrometry. Both scent marks and gland contents consisted mainly of short- to medium-chain fatty acids, a complex series of medium- and long-chain esters, indole,...
Article
Full-text available
Twenty-two components of the odour of the anal-gland secretions of a male and a female yellow mongoose Cynictis penicillata were identified by dynamic solvent effect sampling, gas-liquid chromatography and mass spectrometry. The odour volatiles were considerably more diverse than those reported from the anal gland secretions of Herpestes auropuncta...
Article
Full-text available
Volatiles emitted by male Amblyomma hebraeum while feeding on a rabbit were quantitatively sampled by the dynamic solvent effect and analysed by capillary gas-liquid chromatography and mass spectrometry. Changes in emissions of 2-methyl propanoic acid, benzaldehyde and 2-nitrophenol paralleled reported increases in the attractiveness of males to co...
Article
A method for the derivatization of volatiles collected using the dynamic solvent effect (DSE) is described. Trimethylsily ethers and esters (using N,O-bis-trimethylsilyltrifluoracetamide) are produced on the porous bed of a DSE concentrator either during or after collection of airborne volatiles. Peak areas obtained in the gas chromatographic analy...
Article
Full-text available
Triads of male NMRI mice were housed together and dominance hierarchies allowed to form. At age 19 weeks the mice were ranked on the basis of wins in spontaneous aggressive encounters, and whole-body volatiles were sampled by the dynamic solvent effect and quantitatively analysed by capillary gas chromatography. At age 26 weeks the mice were again...
Article
Full-text available
The volatile components of the anal gland secretion of an adult, male, Ictonyx striatus were separated and identified by dynamic solvent effect sampling, capillary gas-liquid chromatography, and mass spectrometry. The major component was 2-ethylthiacyclobutane. Nine other sulphur compounds, a ketone, and a hydrocarbon were also identified. Some of...
Article
Full-text available
A sample inlet, based on the static solvent effect has been designed and constructed. The inlet can handle samples up to 20 μl which allows for the detection, using an F. I. D., of constituents in the parts per billion range. The reproducibility of the inlet in terms of peak percentage area is around 1% relative standard deviation over a range of c...
Article
Full-text available
A sampling system for high resolution gas-liquid chromatography, based on the dynamic solvent effect, is described. Volatiles are accumulated off-line in a concentrator/injector and delivered to the column using an on-line inlet. Volatiles may be accumulated from gaseous or liquid matrices; they may be transferred to these by gas sparging or solven...
Chapter
This chapter discusses the solvent effect in gas liquid chromatography. The solvent effect is a phenomenon which may be employed as one of the many ways of sample introduction in gas-liquid chromotography. More particularly it is one of the three modes of solute focusing. It is an especially effective means of quantitatively and reproducibly transf...
Article
During work on solvent effect inlets, it was found that PTFE absorbs a considerable quantity of hydrocarbon which is subsequently slowly released. This can cause serious tailing of chromatographed solvent peaks and baseline drift in temperature programmed runs if a PTFE joint is used, e. g. to join a column to a packed bed inlet. The authors found...
Article
A process is described for manufacturing nickel capillary tubing, in lengths up to 100 m, with an internal diameter between 100 and 500 μm and a wall thickness of 50 μm.Steel wire is continuously plated in a bath, 5 m long, containing the plating solution. The wire is cathodic and a nickel anode is used. The nickel-coated wire is cut to suitable le...
Article
Dassen Island lies 9 km off the W coast of South Africa. Its terrestrial mammal fauna consists of introduced populations of Felis catus, rabbit Oryctolagus cuniculus and house mouse Mus musculus. The cat population increased from 20-25 cats in May 1979 to 65-85 in March 1981. Rabbits and birds contributed almost equally to the cats' diet. Since mos...
Article
Solute focussing using the solvent effect is usually carried out in an open tube. Under such circumstances the sample film can be unstable and this leads to peak distortion. It is shown that when the sample film is formed in a packed bed, the film is much more stable, even when polar solvents are used. A further advantage of packed beds is that lar...
Article
Full-text available
Numbers of Felis catus on Dassen Island increased from 20-25 in May 1979 to 37-50 in June 1980. Kittens were born in 8 months of the year with birth peaks in October-November and in January. Mean litter size was 2.7 and 80% of kittens born between August 1979 and January 1980 survived until June 1980. Kittens died from starvation and disease. In Ju...
Article
Thesis (DPhil)-Universiteit van Pretoria, 1988.

Questions

Questions (2)
Question
An urn contains an unknown number of balls of one colour; A. A ball is drawn and replaced with a different colour; B. The draw is repeated and if the ball is colour A it is replaced by colour B, if it is B it is returned to the urn. The number of B initially climbs steeply, then more slowly and reaches a limit when all the balls are B. The practical application is to estimate the number of balls without having to draw and replace all of them.
Is there a model to estimate (with confidence intervals) the number of balls in an urn containing an unknown and countable (in practice less than 1000) number of balls, all of the same colour by drawing and replacement with balls of a different colour, that does not require all of the balls to be drawn and replaced ?

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Project (1)
Project
To develop a test for camera traps that will accurately predict how well they will work when used to record the presence and behaviour of wild animals in the field. Instead of a walking human target, or uncontrolled encounters between wild animals and cameras in the field that are currently used in comparative camera trap tests, I will use trained domestic dogs of various sizes to rigorously test and compare cameras under controlled conditions. For the first time this will; - provide a direct quantitative measure of how well camera taps perform, - allow direct comparisons between makes and models so that researchers can choose which best suits their purpose, and - detect weaknesses in design that might make some makes and models unfit for some purposes.