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Trapping is an effective strategy for control of invasive wild pig ( Sus scrofa ), but eradication of populations via trapping alone typically is impractical throughout much of the species’ introduced range. Consequently, recovery of wild pig populations to pre-trapping levels following control is a major impediment to success of long-term control. In this study, we conducted camera-trap surveys to monitor recovery of two wild pig populations immediately following density reductions achieved via trapping on two sites on the Savannah River Site, SC. We used spatial capture-recapture models to estimate wild pig density during seven 3 week periods spanning 12 months to: (1) determine the time required for populations to recover to pre-trapping levels; and (2) evaluate trends in population growth, density, and distribution during recovery. Recovery of both wild pig populations started immediately after trapping ceased, with populations reaching pre-trapping levels in 3 and 5 months. Threeweek population growth rates for each wild pig population during recovery averaged 1.28 (range = 1.11–1.39 on site 1) and 1.24 (range = 0.64–1.92 on site 2), which corresponded to a 345% and 132% increase in abundance (an increase of 141 and 126 individual wild pigs on site 1 and 2, respectively) of each population by the last survey period. Rapid recovery and growth beyond pre-trapping levels of wild pig populations likely were driven by residual wild pigs not removed by trapping and compensatory reproduction and immigration. Our study is one of the first to provide information on how quickly wild pig populations can recover following overall density reductions of 54–68% and indicates practitioners should be prepared to reinitiate trapping efforts in as little as 3 months to prevent recovery of wild pig populations following control.

Managers of ecosanctuaries often need to make decisions in the face of uncertainty. Model-based tools which aim to assist this process, for example proof-of-absence models, are underpinned by assumptions about the behaviour of target animals, including their spatial movements. In some cases, however, there are few empirical data to draw on to inform these models. The movement behaviour of individual pests in low-density environments, as well as the dispersal of juveniles away from their natal location, is poorly understood for many species, including the ship rat (Rattus rattus). We document probable ship rat incursions and a breeding event within a pest-fenced ecosanctuary in Nelson, New Zealand. A comparison of genetic profiles suggested breeding had taken place, with 13 of 18 rats captured likely to be a family group (mother and likely three litters of offspring). Straight line distances from the recovery location of the putative mother to those of her probable offspring ranged up to a maximum of 1510 m, but were mostly within 200 m. No significant effect of sex, weight or head-body length on movement distance was found. Rat captures and detections appeared to be concentrated around waterways. The presence of unrelated rats in the capture sample points to eradication survivors, several separate incursion events, or a combination of both. Contributions of new data, such as this, help ecosanctuary managers by guiding better design of efficient pest detection networks, and improve models that aid their decision-making.

1. Invasive plants destroy the structure and function of many ecosystems but removal is expensive, so the likelihood of success should be assessed before a major control programme commences. Trial clearings can clarify how best to design and perform broad-scale clearing programmes. Such trials need to consider the range of conditions that might affect the outcome of control operations, not least the duration of invasion before clearing commences, a parameter that has rarely been considered previously. 2. The recovery of plant communities was monitored over 6 years in a Portuguese coastal dune system after the removal of invasive Acacia longifolia plants, together with the underlying litter in half of the cleared areas but not in the remainder. Areas that had been invaded for >20 years (longinvaded) as opposed to <7 years (recently invaded) were compared. 3. After the removal of A. longifolia, recently invaded areas had more exotic plant species but also higher native species richness, plant cover, initial diversity and species turnover rates than longinvaded areas. Generalist native species were initially very abundant in cleared areas but progressively gave way to species more typical of dunes. Six years after clearing, many species that usually occur on dunes were still missing. Therophytes were the most abundant life form immediately after clearing, but nanophanerophytes, chamaephytes and A. longifolia increased with time. Seedlings of A. longifolia were most abundant in long-invaded areas, but litter removal along with plants promoted increased plant species richness and cover and decreased susceptibility to reinvasion. 4. Synthesis and applications. A number of variables can affect the outcome of clearing invasive plant species. For A. longifolia on Portuguese dunes, recently invaded areas should be prioritized and thick litter layers should be removed along with the invader. Even so, recovery of native flora was not complete in this study, and other management actions are needed to supplement clearing operations, for example propagation of native species or prescribed fires to deplete the invasive species seed bank. Although complete restoration of the ecosystem will almost always be impossible, it should be possible in the long term to create an ecosystem with a structure and function that resembles the original habitat.

Molecular analyses are frequently used to assess biological gene flow and dispersal, yet recent data suggest that the operation of density-dependent priority effects often leads to underestimation of species movement patterns and associated invasive potential. Although individual movement is broadly considered to promote connectivity among populations, emerging genetic evidence on a range of scales indicates that it often fails to do so; instead, it can be a strategy that allows first colonizers to wedge a ‘foot in the door’ when new space becomes available. Founding lineages can then rapidly dominate, blocking colonization by later arrivals; subsequent invasion opportunities may be contingent on the extirpation of locals. Many contemporary studies, however, ignore the role of such density-dependent priority effects, and thus fail to assess major differences between movement and establishment. Understanding the role of these processes in the successful establishment of dispersing organisms is critical if we are to predict distributional range shifts and deal with invasive pest species.

Unfenced sites on mainland New Zealand have long been considered impossible to defend from reinvasion by possums, and are thus unsuitable for eradication. In July 2019, we began eliminating possums from 11,642 ha (including approximately 8700 ha of suitable possum habitat) in South Westland, using alpine rivers and high alpine ranges to minimise reinvasion. Two aerial 1080 (sodium fluoroacetate) applications, each with two pre-feeds, were used. Here, we detail the effort to mop up existing possums and subsequent invaders in the 13 months following the aerial operation. Possums were detected and caught using a motion-activated camera network, traps equipped with automated reporting and a possum search dog. The last probable survivor was eliminated on 29 June 2020, 11 months after the initial removal operation. Subsequently, possums entered the site at a rate of 4 per year. These were detected and removed using the same methods. The initial elimination cost NZD 163.75/ha and ongoing detection and response NZD 15.70/ha annually. We compare costs with possum eradications on islands and ongoing suppression on the mainland.

Feral cats (Felis catus) have a negative impact on native biodiversity in New Zealand. As such, their populations require careful management and monitoring of the effectiveness of these management operations. We used camera traps to assess (1) effectiveness of an intensive cat control operation, and (2) the level of reinvasion six months later. Cat abundance was estimated on a pastoral property in Hawke’s Bay, North Island, New Zealand, subject to cat control using trapping and shooting. Forty cameras were placed on a grid with 500 m spacing and deployed for a total of nine weeks: (1) pre-control, (2) immediately post-control, and (3) six-months post control. Cat abundance was estimated using an index-manipulation-index (IMI) method. The IMI method estimated an c. 84 % decrease in cat abundance immediately post-control, suggesting the operation worked well at removing most resident cats at this site. The detections observed six months later suggest reinvasion was very low.

The reinvasion and recruitment of overwintering cyanobacteria in sediments in spring have an important impact on cyanobacterial blooms in summer and autumn, but until now, this process has not been observed in natural water bodies. In this study, wireless sensors and automatic water sample collection systems were used to carry out continuous high-frequency monitoring of cyanobacteria and related environmental indicators in Meiliang Bay, Lake Taihu, during a northwest wind event in spring. The results showed that there were many dormant cyanobacteria seeds in the sediments of Lake Taihu. These cyanobacterial seeds were easily resuspended from sediments, allowing them to reinvade and remain in the overlying water. Simultaneously, the water temperature exceeded the recovery temperature after the northwest wind event and the available light was sufficient to allow the reinvading cyanobacteria to recruit. The circadian photosynthetic rhythm of these recruited cyanobacteria eventually led to a rapid increase in dissolved oxygen in the water body during the south wind phase to a supersaturated state, and periodic diurnal fluctuations of the water body dissolved oxygen saturation curve. This study provided direct evidence for fully understanding the annual cycle of cyanobacterial blooms.

Invasive species are a major driver of native species declines, frequently resulting in a reduction of ecosystem function. Though control of invasive species is often beneficial, it can create other ecological issues. However, studying the results can give insight into the benefits of removal and most effective management techniques. A model invasive species to test the effects of removal is the red‐imported fire ant (Solenopsis invicta, hereafter RIFA), which depredates and competes with native species. We hypothesized that following removal, RIFA would recolonize treated areas from untreated borders, resulting in reinvasion and higher densities due to elimination of competition from native species that would also be extirpated by treatments. To test our hypothesis, we compared RIFA relative abundance on large sites (>400 ha) treated with a granular insecticide (Extinguish Plus, Central Life Sciences, Schaumburg, IL) in southwest Georgia, USA. Extinguish Plus effectively removed RIFA, but the treated sites were reinvaded approximately 14 months after treatment with higher densities of RIFA than on untreated areas, potentially reflecting release from competition from native ants removed by treatments. Invasive species removal may elicit a rapid recolonization via a density‐dependent response mechanism and potentially increase abundance of the target species. Management strategies integrating temporal and spatial replication of control measures and multiple management techniques will be most successful in controlling invasive species.

Dispersal is a fundamentally important aspect of animal behaviour, but empirical data describing it are lacking for many species. Here, we report on a field study aimed at measuring post-weaning movement distances of juvenile ship rats (Rattus rattus) and their mother away from a known natal nest site in an area with low conspecific population density. The movement behaviour of invasive species at low density is of particular interest, as it can inform design of surveillance arrays to detect incursion into predator-free areas. Detecting a single invading individual requires intensive effort. An alternative approach is to focus on detecting newlyestablished breeding populations, while they are still spatially-restricted and able to be eliminated with timely and effective incursion response. We released a bio-marked rat mother and litter into an area recently treated with sodium fluroacetate (1080) and monitored their behaviour for 12 weeks. Final capture locations ranged up to 675 m from the release location for the juveniles, with 796 m between known siblings. The total range length for the mother exceeded 1.5 km. Although we found no evidence that the movements of the family as a collective extended further than those of the mother alone, the concept of targeting detection efforts to breeding populations warrants further investigation due to the improved probability of detecting at least one of multiple individuals, rather than a single invader.

Movements that extend beyond the usual space use of an animal have been documented in a range of species and are particularly prevalent in arid areas. We present long-distance movement data on five feral cats (Felis catus) GPS/VHF-collared during two different research projects in arid and semi-arid Australia. We compare these movements with data from other feral cat studies. Over a study period of three months in the Ikara-Flinders Ranges National Park, 4 out of 19 collared cats moved to sites that were 31, 41, 53 and 86 km away. Three of the cats were males, one female; their weight was between 2.1 and 4.1 kg. Two of the cats returned to the area of capture after three and six weeks. During the other study at Arid Recovery, one collared male cat (2.5 kg) was relocated after two years at a distance of 369 km from the area of collar deployment to the relocation area. The movements occurred following three years of record low rainfall. Our results build on the knowledge base of long-distance movements of feral cats reported at arid study sites and support the assertion that landscape-scale cat control programs in arid and semi-arid areas need to be of a sufficiently large scale to avoid rapid reinvasion and to effectively reduce cat density. Locally, cat control strategies need to be adjusted to improve coverage of areas highly used by cats to increase the efficiency of control operations.