Peri‐Urban Deer Control Is Challenging: Three Case Studies and Strategies for Improved Outcomes

Australian wild deer populations have significantly expanded in size and distribution in recent decades. Due to their role in pathogen transmission, these deer populations pose a biosecurity risk to the livestock industry. However, little is known about the infection status of wild deer in Australia. The intestinal parasite Entamoeba bovis has been previously detected in farm and wild ruminants worldwide, but its epidemiology and distribution in wild ruminants remain largely unexplored. To investigate this knowledge gap, faecal samples of wild deer and domestic cattle from south-eastern Australia were collected and analysed for the presence of Entamoeba spp. using PCR and phylogenetic analysis of the conserved 18S rRNA gene. E. bovis parasites were detected at high prevalence in cattle and wild deer hosts, and two distinct Entamoeba ribosomal lineages (RLs), RL1 and RL8, were identified in wild deer. Phylogenetic analysis further revealed the existance of a novel Entamoeba species in sambar deer and a novel Entamoeba RL in fallow deer. While we anticipated cross-species transmission of E. bovis between wild deer and cattle, the data generated in this study demonstrated transmission is yet to occur in Australia. Overall, this study has identified novel variants of Entamoeba and constitutes the first report of Entamoeba in fallow deer and sambar deer, expanding the host range of this parasite. Epidemiological investigations and continued surveillance of Entamoeba parasites in farm ruminants and wild animals will be required to evaluate pathogen emergence and transmission to livestock.

Deer species (fallow, red, sambar, chital, rusa and hog deer) have formed wild populations in Australian habitats ranging from arid woodland to rainforest and are a growing management issue. Data were obtained via an Australia-wide land-manager survey that collected information on the liberation, distribution, abundance and management of wild deer in Australia. It is estimated that there are 218 wild deer herds in Australia with 7% of these herds originating from acclimatisation society releases, 35% from deer farm escapes/releases and 58% from translocations (deliberate releases). On average, herds released by acclimatisation societies are estimated to be 107 years old, herds that have escaped from (or been released from) deer farms are 9 years old, and transplanted herds are 6 years old. It is estimated that Australia currently has 200 000 wild deer, with 85% of these deer originally released by acclimatisation societies, 6% through escapes/releases from deer farms and 9% by translocation. Poor knowledge of the impacts of wild deer by land managers and the absence of consistent legislation governing the management of farmed and wild deer are factors that have exacerbated deliberate releases of deer and the escape of deer from farms. Management strategies for wild deer in Australia need to be developed by land managers to address the escape and release of deer from farms, the illegal translocation of deer into the wild and the management of existing wild deer herds.

Context Some populations of introduced species cause significant undesirable impacts but can also act as reservoirs for genetic diversity. Sambar deer (Cervus unicolor) are ‘Vulnerable’ in their native range and invasive in Australia and New Zealand. Genetic data can be used to determine whether these introduced populations might serve as genetic reservoirs for declining native populations and to identify spatial units for management. Aims We aimed to identify the provenance of sambar deer in Australia and New Zealand, and to characterise their genetic diversity and population structure. Methods We used mitochondrial control region sequences and 18 nuclear microsatellite loci of 24 New Zealand and 63 Australian sambar deer collected across continuous habitat in each location. We estimated genetic diversity and population differentiation by using pairwise FST, AMOVA, and Structure analyses. We compared our data with 27 previously published native and invasive range sequences to identify phylogenetic relationships. Key results Sambar deer in Australia and New Zealand are genetically more similar to those in the west of the native range (South and Central Highlands of India, and Sri Lanka), than to those in the east (eastern India, and throughout Southeast Asia). Nuclear genetic diversity was lower than in the native range; only one mitochondrial haplotype was found in each introduced population. Australian and New Zealand sambar deer were genetically distinct but there was no population structure within either population. Conclusions The genetic differences we identified between these two introduced populations at putatively neutral loci indicate that there also may be underlying diversity at functional loci. The lack of population genetic structure that we found within introduced populations suggests that individuals within these populations do not experience barriers to dispersal across the areas sampled. Implications Although genetic diversity is reduced in the introduced range compared with the native range, sambar deer in Australia and New Zealand harbour unique genetic variants that could be used to strengthen genetic diversity in populations under threat in the native range. The apparent high levels of gene flow across the areas we sampled suggest that localised control is unlikely to be effective in Australia and New Zealand.

Red deer (Cervus elaphus) have been in Australia for over 150 years. The first documented release in Queensland was on Cressbrook Station in 1873. Following further releases they have spread through the Brisbane, Mary, and Burnett River Valleys to have an estimated population of 15,000 animals. Red deer were a protected species for many years in Queensland, but in 2009 were declared a Class 3 pest animal. The Invasive Animals Cooperative Research Centre National Feral Deer Management Workshop in 2005 reported there was a lack of credible, scientific knowledge about deer in Australia. This project addressed the following research questions relating to wild red deer in south-eastern Queensland: • What is the optimal method for estimating abundance? • What is their annual and seasonal home range? • Do red deer exhibit habitat preferences and what factors affect those preferences? Estimating Abundance: Walked line transect distance sampling, aerial line transect distance sampling, vehicle based spotlight counts and faecal pellet counts were used to estimate or obtain indices of abundance of wild red deer at Cressbrook Dam. For each method the labour input, costs and precision were estimated. Spotlighting performed best overall when comparing labour and costs with precision, but had a number of limitations. Walked line transects gave estimates of adequate and repeatable precision but the method was expensive for both labour and equipment. Aerial survey estimates were quick, relatively cost-effective and comparable to walked line transect estimates, but not as precise as other methods. Faecal pellet counts were expensive in terms of labour, but were very precise. Choosing a method for counting deer will be site and circumstance specific, and some recommendations are provided to assist land managers choose a method. The density of wild red deer at the study site was very high - estimated to be between 26 and 30 deer/km2. Home Range: Wild red deer were fitted with GPS collars to provide location information every 90 minutes. Data were obtained from 22 collared deer – 11 male (4 young adult, 7 mature adult) and 11 female (1 young adult, 10 mature adult). Annual home range was estimated using the 95% Local Convex Hull method to be approximately 359 ha for hinds and 1,323 ha for stags. The data indicate that the size of seasonal home range may be linked to seasonal conditions. Stags at our study site showed no elevated activity in summer compared to European reports. The home ranges at our study site were very large considering the high deer densities encountered. Habitat Use: Habitat preferences of GPS collared deer were explored by computing the resource selection ratios. The available and used resources for individual animals were compared at the home range level for various habitat components. The large data set (over 117,000 deer locations) allowed in-depth examination of possible factors that might affect habitat use. I examined foliage projective cover, aspect and slope to explore deer habitat preferences during the winter, summer and rut for day vs. night. Hinds showed a preference for using heavier cover in the day compared to night regardless of season, whereas stags only showed this preference in winter. Hinds showed a preference for southerly facing aspects in all seasons. Stags showed southerly and easterly preferences in winter and easterly preferences in summer. Hinds generally selected gentle to medium slopes, while stags chose moderate to steep slopes. Given the spread of deer generally in Australia most land managers will likely work towards population maintenance or reduction. Estimating deer abundance will be critical in monitoring progress towards set targets. If population reduction of wild red deer is desirable the best strategy may be to reduce the number of hinds. The home range data suggest that hinds have smaller home ranges than stags. Habitat preferences observed indicate that night time is the best time to target deer in less heavily vegetated environments where they are more visible.

ABSTRACTThe quality of venison from farmed deer were evaluated based on chemical composition, palatability scores, W‐B shear force, ultimate pH, and color. The samples of venison were derived from javan rusa (Cervus timorensis russa), moluccan rusa (Cervus timorensis moluccensis), sambar (Cervus unicolor brookei), fallow (Dama dama) and imported red deer (Cervus elaphus). Moluccan rusa and red deer were fed grass. Javan rusa, sambar and fallow deer were fed concentrate. The venison obtained from grazing deer (grass‐fed) gave higher moisture content (75.3%) than concentrate‐fed or confinement‐raised deer (74.4%) and imported venison (70.62%). Fat content in venison shows some differences between muscles and species. The concentrate‐fed animals had a higher (P < 0.05) fat content in the venison than the grazing deer. Temperate deer (fallow and red deer) showed higher (P < 0.05) fat content than tropical deer (rusa and sambar deer). Venison obtained from concentrate‐fed deer showed normal ultimate pH values (pH ≤ 6.0) and more reddish in color than grass‐fed deer. The concentrate‐fed venison produced slightly higher (P > 0.05) palatability scores than grass‐fed venison. Feeding regimens (grass‐fed vs. concentrate‐fed) significantly (P < 0.05) influenced fat composition in the venison of farmed deer in this study.

The first finding of Dictyocaulus cervi and Dictyocaulus skrjabini (Nematoda) in feral fallow deer (Dama dama) in Australia

ABSTRACTAustralia's invasive deer populations continue to expand in abundance and distribution, yet there is limited information on their movement patterns and habitat preferences. This inhibits the prioritisation of areas for control and conservation protection. We tracked 20 fallow deer (Dama dama), 5 red deer (Cervus elaphus), and 14 sambar deer (Rusa unicolor) to characterise their seasonal movement and habitat preferences in alpine and sub‐alpine southeastern Australia. Autocorrelated kernel density estimated annual home ranges (km2 ± SE) averaged 226.9 ± 54.3 for male, and 55.1 ± 46.5 for female fallow deer, 70.2 ± 35.5 for female red deer, and 25.3 ± 4.0 for male, and 80.7 (one individual) for female sambar deer. Red and sambar deer were mainly restricted to eucalyptus forest/woodland (97% of fixes for sambar, 92% for red) and native grassland (2% of fixes for sambar; 8% for red). Fallow deer, however, were more generalist, and used comparatively less eucalypt forest/woodland (73%), spending more time in cleared areas (14%), and native grasslands (13%). Seasonal resource selection functions (RSFs) showed that, relative to eucalypt forest/woodland, fallow deer preferred cleared land for all seasons except summer, heathland for all seasons except winter, and inland aquatic areas in summer. All species tended to inhabit higher elevations in summer (average: 1517 m ASL for fallow; 1709 m ASL for red; 1463 m ASL for sambar), and lower elevations in winter (average: 1344 m ASL for fallow; 1483 m ASL for red; 1102 m ASL for sambar). Additionally, seasonal RSFs showed that red deer exhibited a preference for higher elevations within their available range in every season except winter, when they preferred lower elevations. Of concern, we found that sambar deer showed a preference for previously burnt areas in autumn (53% of fixes) and spring (89% of fixes), preferring areas with low to moderate and high‐severity fire damage. Prioritising areas for control and conservation should be informed by deer movement and habitat preferences, and differences in such preferences between the three species studied herein suggest the need for tailored approaches for control to be effective in reducing their numbers and impacts on ecosystems.

The Common Fallow Deer (Dama dama; hereafter “fallow deer”) has been widely translocated from its native Mediterranean range and is now present on all continents except Antarctica. In some countries—such as Australia—introduced populations of fallow deer have increased in range and abundance, negatively affecting agricultural production. However, little is known about how this species uses these agricultural landscapes annually, seasonally, or daily. We used GPS collars to track the hourly movements of 68 adult fallow deer (25 males, 43 females) at 3 sites in mixed pastoral farmland (a mosaic of open eucalypt woodland and pasture) in eastern Australia between 2020 and 2024. We estimated annual and monthly home ranges, daily distance moved, and diel movement cycles. As expected, annual home ranges (using the biased random bridge method) were larger for males (median = 1,848.1 ha, 95% CrI: 929.2 to 3,584.0 ha) than females (median = 646.3 ha, 95% CrI: 368.1 to 1,068.5 ha), and home ranges and core areas were similar across the 3 sites. Both sexes had a strong crepuscular movement pattern that was consistent across sites. Male fallow deer increased their movement rates in April–May (i.e., during the mating season), and their movement patterns were most restricted during summer. Female fallow deer movements were more consistent across the year than those of males, but movement patterns were also most restricted during summer. There was substantial individual variation in daily movement patterns between and within sites, especially during the mating season. Most individuals exhibited strong site fidelity, but some males and females made short excursions (up to a week and 10 km) from their home range. The strong site fidelity of fallow deer suggests that management strategies utilizing repeated culling will be most effective at reducing overabundant fallow deer populations in Australian agricultural landscapes.

Invasive species have established populations around the world and, in the process, characteristics of their realized environmental niches have changed. Because of their popularity as a source of game, deer have been introduced to, and become invasive in, many different environments around the world. As such, deer should provide a good model system in which to test environmental niche shifts. Using the current distributions of the six deer species present in Australia, we quantified shifts in their environmental niches that occurred since introduction; we determined the differences in suitable habitat between their international (native and invaded) and their Australian ranges. Given knowledge of their Australian habitat use, we then modeled the present distribution of deer in Australia to assess habitat suitability, in an attempt to predict future deer distributions. We show that the Australian niches of hog (Axis porcinus), fallow (Dama dama), red (Cervus elaphus), rusa (C. timorensis), and sambar deer (C. unicolor), but not chital deer (A. axis), were different to their international ranges. When we quantified the potential range of these six species in Australia, chital, hog, and rusa deer had the largest areas of suitable habitat outside their presently occupied habitat. The other three species had already expanded outside the ranges that we predicted as suitable. Here, we demonstrate that deer have undergone significant environmental niche shifts following introduction into Australia, and these shifts are important for predicting the future spread of these invasive species. It is important to note that current Australian and international environmental niches did not necessarily predict range expansions, thus wildlife managers should treat these analyses as conservative estimates.

Context Introduced sambar deer (Cervus unicolor) are increasing in south-eastern Australia, and both volunteer and contract ground-based shooters are being used by management agencies to control their undesirable impacts. However, little is known about the effectiveness and costs of volunteer and contract shooters for controlling deer populations in Australia. Aims We evaluated the effectiveness and costs of volunteer and contract ground-based shooters for controlling sambar deer and their impacts in a 5-year management program conducted in and around alpine peatlands in Alpine National Park, Victoria. Methods Ground-based shooting operations were organised in two blocks. Within each block, four ~4200-ha management units were delimited, of which two were randomly assigned as treatment (ground-based shooting) and two as non-treatment (no organised ground-based shooting). In the treatment units, ground-based shooting was conducted using either volunteers or contractors. Each shooting team recorded their effort and the numbers of deer seen and shot, and used a GPS to record their track log and the time and locations of deer shot. Key costs were recorded for both shooter types. Key results The catch per unit effort of contract shooters was four times greater than that of volunteer shooters. Both shooter types were most effective during the first half of the night and prior to sunrise, and when using a vehicle with a spotlight or walking with thermal-vision equipment. During the day, the use of gundogs to indicate deer significantly increased the success rate of volunteer shooters. Both volunteer and contract shooters used roads and tracks to move in the landscape, but contractors covered more ground than did volunteers. After accounting for key operational costs, the cost per deer killed was 10.1% higher for contract than volunteer shooters. Conclusions The effectiveness of ground-based shooters is increased by operating at night using vehicles, spotlights and thermal-vision equipment. Contract shooters kill sambar deer at a faster rate, but are slightly more expensive per deer killed, than are volunteer shooters. Implications Ground-based shooting is likely to be most effective when conducted at night with thermal-vision equipment, and in areas with a high density of roads and tracks.

Estimating diet is often an important step in understanding and managing the impacts of ungulates, particularly for non‐native species, but there is uncertainty about whether rumen contents should be assessed using macroscopic or microhistological methods or both. Introduced sambar deer (Cervus unicolor) have a large and increasing distribution in south‐east Australia, and there is concern about their impacts on native and non‐indigenous plant species. We estimated the diets of 102 sambar deer harvested during 2007–2009 using macroscopic and microhistological rumen analysis techniques. We identified 105 plant species in the diets of sambar deer, 61 identified with both techniques and 22 identified only macroscopically or only microhistologically. Rumen species richness was 70% greater using the microhistological technique. Estimates of taxonomic (i.e., monocot and dicot) and functional (i.e., fern, shrub–tree, forb, climber, grass, and grass‐like) group composition by the 2 techniques were similar. Shrubs–trees dominated the diet (macroscopic, 49.7%; microhistological, 52.7%), followed by grasses (macroscopic, 22.7%; microhistological, 17.5%) and ferns (macroscopic, 20.6%; microhistological, 22.2%). We identified 9 non‐indigenous plant species, 2 of which we identified using only the microhistological technique. We detected seeds of the weed blackberry (Rubus fruticosus aggregate), sometimes in large amounts, only with the macroscopic technique, whereas we detected foliage of that species with both techniques. Both techniques classified sambar deer as an intermediate mixed feeder closer to a concentrate selector–browser than a bulk and roughage feeder. However, both techniques detected seasonal differences in the percentages of taxonomic and functional groups in the diet; sambar deer were more grazers in autumn and more browsers in spring. Our results indicate that both macroscopic and microhistological techniques may need to be used when it is important to identify plant species in the diet, as is often the case for non‐native ungulates. However, either technique can be used to estimate broader taxonomic and functional diet composition, including feeding type. © The Wildlife Society, 2011

Context Helicopter-based shooting has been widely used to kill deer in Australasia, but the animal welfare outcomes of this technique have not been evaluated. Aim To assess the animal welfare outcomes of helicopter-based shooting of deer in Australia by quantifying the fates of deer seen and shot at, the duration of procedures and the number and location of bullet wounds in deer. Methods Three deer control operations were assessed. These operations targeted: (1) chital deer (Axis axis) in Queensland, (2) fallow deer (Dama dama) in Australian Capital Territory and (3) fallow deer in New South Wales. For each operation, an independent veterinarian conducted ante-mortem (i.e. from the helicopter as shooting occurred) and post-mortem (i.e. from the ground after shooting had ceased) observations. The ante-mortem data were used to estimate the proportion of deer seen that were shot, chase time (CT), time to insensibility (TTI) and total time (TT; CT + TTI). The numbers and locations of bullet wounds were recorded post-mortem. Key results Ante-mortem and post-mortem observations were performed for 114–318 and 60–105 deer, respectively, in the three operations. Shots were fired at 69–76% of deer that were observed. Median CT ranged from 73 to 145 s. Median TTI ranged from 17 to 37 s and median TT ranged from 109 to 162 s. The mean number of bullet wounds per deer ranged from 1.43 to 2.57. Animal welfare outcomes were better in the two fallow deer operations than in the chital deer operation. In both fallow deer operations, most deer were shot multiple times and at least once in the head or thorax. In contrast, chital deer were shot fewer times and less often in the head or thorax, and non-fatal wounding was observed. Conclusions The best animal welfare outcomes were achieved when helicopter-based shooting operations followed a fly-back procedure and mandated that multiple shots were fired into each animal. Implications Animal welfare outcomes for helicopter-based deer shooting in Australia could be improved with a national-level standard operating procedure requiring helicopters to fly back over shot animals and repeatedly shoot animals in the head or thorax.

Context: Deer (Cervidae) populations are increasing in many global regions, leading to concerns about their impacts on temperate forests. Advancing evidence‐based management requires a detailed understanding of the dietary habits of deer and how these are shaped by resource availability. Methodology: We studied the diet of fallow deer (Dama dama) in North Wales (United Kingdom), using faecal DNA metabarcoding. Samples were collected monthly from three woodlands during 2019–2021. Tree surveys and seasonal ground flora surveys were conducted in these woodlands and seven additional woodlands. Preference analyses were used to assess the consumption of plant taxa relative to their availability. Results: The fallow deer consumed high proportions of bramble (Rubus fruticosus agg.) across the seasons, especially in the winter months. Diet diversity was significantly lower in winter compared to the other seasons, suggesting that the deer were bulk foraging on a widely available, predictable resource to conserve energy during winter. Grasses did not form a major component of the diet in any season. The preference analysis showed that spatially clustered woody taxa (e.g. Betula sp., Corylus sp. and Fraxinus sp.) occurred less often than expected in the diet, while widespread woody species occurred in the diet more often than expected (e.g. Rosa sp., Prunus sp. and Quercus sp.). Practical implication: The expansion of deer populations in the United Kingdom has occurred alongside the recovery and maturation of degraded or planted forests since the middle of the 20th century. Despite reduced light availability in these closed‐canopy forests and increased herbivory pressure, bramble has remained a dominant understory plant compared to other less herbivory‐tolerant plant species. Perhaps as a consequence, bramble has become the winter survival resource for this fallow deer population, remaining a prominent dietary component throughout the year. With increasing disturbance from extreme weather and tree diseases leading to a more open canopy structure, bramble cover is set to increase in European forests, which could support further expansion of deer populations. As we work to expand tree cover and enhance forest resilience and biodiversity, we should seek to understand the dynamic interactions of increasing deer populations with rapidly changing treescapes.

Context Introduced populations of sambar deer (Cervus unicolor) and rusa deer (Cervus timorensis) are present across south-eastern Australia and are subject to local population control to alleviate their negative impacts. For management to be effective, identification of dispersal capability and management units is necessary. These species also readily hybridise, so additional investigation of hybridisation rates across their distributions is necessary to understand the interactions between the two species. Aims Measure the hybridisation rate of sambar and rusa deer, assess broad-scale population structure present within both species and identify distinct management units for future population control, and measure the likely dispersal capability of both species. Methods In total, 198 sambar deer, 189 rusa deer, and three suspected hybrid samples were collected across Victoria and New South Wales (NSW). After sequencing and filtering, 14 099 polymorphic single-nucleotide polymorphism (SNP) markers were retained for analysis. Hybridisation rates were assessed before the data were split by species to identify population structure, diversity indices, and dispersal distances. Key results Across the entire dataset, 17 hybrids were detected. Broad-scale population structure was evident in sambar deer, but not among the sites where rusa deer were sampled. Analysis of dispersal ability showed that a majority of deer movement occurred within 20 km in both species, suggesting limited dispersal. Conclusions Distinct management units of sambar deer can be identified from the dataset, allowing independent population control. Although broad-scale population structure was not evident in the rusa deer populations, dispersal limits identified suggest that rusa deer sites sampled in this study could be managed separately. Sambar × rusa deer hybrids are present in both Victoria and NSW and can be difficult to detect on the basis of morphology alone. Implications Genetic analysis can identify broad-scale management units necessary for population control, and estimates of dispersal capability can assist in delineating management units where broad-scale population structure may not be apparent. The negative impacts associated with hybridisation require further investigation to determine whether removal of hybrids should be considered a priority management aim.

Integrating the interaction between cell wall components through a lignin and neutral detergent fibre ratio as a cell wall digestibility (CWD) index may provide a suitable method for diet quality and fibre digestibility estimation. Predictive faecal-Fourier-transform (FT)-near infrared reflectance spectroscopy (NIRS) equations useful for CWD determination were developed as an integrative assessment of the digestibility and quality of the diet selected by red (Cervus elaphus hispanicus) and fallow (Dama dama) deer in southern Spain. A chemometric regression was used from spectra of faeces and wet chemical rumen contents analysis as reference data coupled with partial least-squares. The accuracy and feasibility of the equations obtained for red and fallow deer samples separately were evaluated, as well as after pooling all samples for both species. The predictive equations had a high linearity with correlation coefficients (r) ranging between 0.89 and 0.99, as well as a reliable accuracy considering the errors of prediction (RMSEP 0.57–0.87), calibration (RMS 0.04–0.45) and cross-calibration (RMSECV 0.80–1.12) in relation to the range of values for which the NIRS calibration was set for each parameter, giving very good RER (residual error value) indices (7.44–13.23). The ability of the calibration equations to predict new samples from the same deer populations was also assessed through an external validation. Equations obtained for the red deer data were successfully applied not only to red deer but also to fallow deer, and vice versa. Feasible CWD simultaneous determination in red and fallow deer was also obtained by using the broad-based equations. There was variation of the CWD index throughout the year and differences between the two deer species. A lower CWD of the forage was recorded in red deer, while a lower CWD ratio was detected at the end of winter coinciding with the highest browsing levels in both species. This technique has potential to enable closer examination of the non-grass variables and distinguish between browse and herbage feeding behaviour. The faecal-NIRS method of CWD ratio determination is a useful, non-invasive tool for monitoring variations in the diet quality of Mediterranean deer in their natural environment.