Motion-sensing Cameras Research Articles

Scatter-hoarding rodents disperse seeds to safe sites in a fire-prone ecosystem

Fire can potentially decimate soil seed banks, even for species that are abundant in fire-prone areas. Many plants, like the widespread and dominant members of the genus Arctostaphylos in the fire-prone California Floristic Province, have seeds that (i) have no clear adaptions for dispersal and (ii) experience lethal fire temperatures if present on or near the soil surface. In this study, we aim to resolve these juxtaposed observations by mechanistically determining how one species, Arctostaphylos patula, is dispersed. To distinguish among dispersal modalities and determine the seed shadow, deposition patterns, and the conditions under which seeds germinate, we employed full-shrub exclosure treatments to monitor fruit removal, used a mark-relocation technique by radioactively labeling seeds, identified dispersers using motion-sensor cameras, and surveyed seedlings following fire to relate natural germination patterns to measured patterns from our experiment. Seed removal from exclosure treatments that allowed rodents access to shrubs was higher than those that prevented rodent access to shrubs, and cameras at radioactively labeled-seed stations failed to detect the presence of any other disperser; thus implicating rodents as the primary disperser of A. patula seeds. This evidence is corroborated by our finding from tracking radioactively labeled seeds that the depth at which rodents bury seeds completely overlaps with the depth from which we observed seedlings germinate following two fire events. Our study extends the boundary of what is understood as a scatter-hoarding seed dispersal syndrome and identifies a mechanism that allows populations of Arctostaphylos to exist in spite of recurrent fires that can be lethal to seeds and hazardous to plant populations.

Avian seed dispersal in a mycoheterotrophic orchid Cyrtosia septentrionalis

Orchid seeds are conventionally thought to be wind dispersed. However, extensive observation with motion sensor cameras shows that birds such as the brown-eared bulbul eat and disperse the seeds of at least one orchid, Cyrtosia septentrionalis.

Using motion-sensor camera technology to infer seasonal activity and thermal niche of the desert tortoise (Gopherus agassizii)

Understanding the relationships between environmental variables and wildlife activity is an important part of effective management. The desert tortoise (Gopherus agassizii), an imperiled species of arid environments in the southwest US, may have increasingly restricted windows for activity due to current warming trends. In summer 2013, we deployed 48 motion sensor cameras at the entrances of tortoise burrows to investigate the effects of temperature, sex, and day of the year on the activity of desert tortoises. Using generalized estimating equations, we found that the relative probability of activity was associated with temperature (linear and quadratic), sex, and day of the year. Sex effects showed that male tortoises are generally more active than female tortoises. Temperature had a quadratic effect, indicating that tortoise activity was heightened at a range of temperatures. In addition, we found significant support for interactions between sex and day of the year, and sex and temperature as predictors of the probability of activity. Using our models, we were able to estimate air temperatures and times (days and hours) that were associated with maximum activity during the study. Because tortoise activity is constrained by environmental conditions such as temperature, it is increasingly vital to conduct studies on how tortoises vary their activity throughout the Sonoran Desert to better understand the effects of a changing climate.

The influence of urban encroachment on squirrel gliders (Petaurus norfolcensis): effects of road density, light and noise pollution

Context Loss and degradation of habitat from urban development is a key threat to the squirrel glider (Petaurus norfolcensis), because its distribution coincides where most people live in Australia. Squirrel gliders are known to occur in or around urban fringes where native vegetation is retained; however, little is known about specific anthropogenic factors that may affect their persistence. Aims We investigated the relative influence of biophysical and urban factors on the use of large hollow-bearing Eucalyptus trees, which are a key resource for squirrel gliders. The study was located in a typical urban growth area located in southern New South Wales. Methods A stratified random sampling approach was used to survey squirrel gliders in urban and rural areas. Infrared, motion-sensor cameras were placed in 34 selected trees for 17 nights to record squirrel glider occupancy and activity. Data on urban (e.g. light and noise pollution levels, road and housing density) and biophysical (e.g. tree height, hollow-bearing tree density, vegetation cover) variables were recorded at each survey tree. Data were statistically analysed using general linear modelling approaches. Key results Squirrel gliders were detected more frequently in the rural matrix (23.4% of camera trap-nights) than in urban areas (9.5%). Model results showed that tree height, and the distance to neighbouring trees, had a significant influence on the occurrence and activity of squirrel gliders. Road density and light pollution were included in ‘best’ models to explain glider activity (a negative influence), and noise pollution negatively influenced glider occurrence. Although gliders used large trees in both urban and rural areas, activity generally decreased as levels of urbanisation increased. Conclusions and implications Access to and availability of key resources such as tall, hollow-bearing trees is critical for gliders to persist in urban environments. Squirrel gliders will tolerate human stressors such as roads, noise and light pollution to a certain extent, but impacts on population viability remain largely unknown. Novel solutions need to be developed to lessen the effects of anthropogenic factors (such as light and noise) on patches of native vegetation retained in urban areas for conservation purposes.

Barriers to seed and seedling survival of once-common Hawaiian palms: the role of invasive rats and ungulates.

Mammalian herbivores can limit plant recruitment and affect forest composition. Loulu palms (Pritchardia spp.) once dominated many lowland ecosystems in Hawai'i, and non-native rats (Rattus spp.), ungulates (e.g. pigs Sus scrofa, goats Capra hircus) and humans have been proposed as major causes of their decline. In lowland wet forest, we experimentally determined the vulnerability of seeds and seedlings of two species of Pritchardia, P. maideniana and P. hillebrandii, by measuring their removal by introduced vertebrates; we also used motion-sensing cameras to identify the animals responsible for Pritchardia removal. We assessed potential seed dispersal of P. maideniana by spool-and-line tracking, and conducted captive-feeding trials with R. rattus and seeds and seedlings of both Pritchardia species. Seed removal from the forest floor occurred rapidly for both species: >50 % of Pritchardia seeds were removed from the vertebrate-accessible stations within 6 days and >80 % were removed within 22 days. Although rats and pigs were both common to the study area, motion-sensing cameras detected only rats (probably R. rattus) removing Pritchardia seeds from the forest floor. Captive-feeding trials and spool-and-line tracking revealed that vertebrate seed dispersal is rare; rats moved seeds up to 8 m upon collection and subsequently destroyed them (100 % mortality in 24-48 h in captivity). Surprisingly, seedlings did not suffer vertebrate damage in field trials, and although rats damaged seedlings in captivity, they rarely consumed them. Our findings are consistent with the hypothesis generated from palaeoecological studies, indicating that introduced rats may have assisted in the demise of native insular palm forests. These findings also imply that the seed stage of species in this Pacific genus is particularly vulnerable to rats; therefore, future conservation efforts involving Pritchardia should prioritize the reduction of rat predation on the plant recruitment stages preceding seedling establishment.

Fatal attraction: vegetation responses to nutrient inputs attract herbivores to infectious anthrax carcass sites.

Parasites can shape the foraging behaviour of their hosts through cues indicating risk of infection. When cues for risk co-occur with desired traits such as forage quality, individuals face a trade-off between nutrient acquisition and parasite exposure. We evaluated how this trade-off may influence disease transmission in a 3-year experimental study of anthrax in a guild of mammalian herbivores in Etosha National Park, Namibia. At plains zebra (Equus quagga) carcass sites we assessed (i) carcass nutrient effects on soils and grasses, (ii) concentrations of Bacillus anthracis (BA) on grasses and in soils, and (iii) herbivore grazing behaviour, compared with control sites, using motion-sensing camera traps. We found that carcass-mediated nutrient pulses improved soil and vegetation, and that BA is found on grasses up to 2 years after death. Host foraging responses to carcass sites shifted from avoidance to attraction, and ultimately to no preference, with the strength and duration of these behavioural responses varying among herbivore species. Our results demonstrate that animal carcasses alter the environment and attract grazing hosts to parasite aggregations. This attraction may enhance transmission rates, suggesting that hosts are limited in their ability to trade off nutrient intake with parasite avoidance when relying on indirect cues.

Carnivore distributions across chaparral habitats exposed to wildfire and rural housing in southern California

Chaparral and coastal sage scrub habitats in southern California support biologically diverse plant and animal communities. However, native plant and animal species within these shrubland systems are increasingly exposed to human-caused wildfires and an expansion of the human–wildland interface. Few data exist to evaluate the effects of fire and anthropogenic pressures on plant and animal communities found in these environments. This is particularly true for carnivore communities. To address this knowledge gap, we collected detection–non-detection data with motion-sensor cameras and track plots to measure carnivore occupancy patterns following a large, human-caused wildfire (1134km2) in eastern San Diego County, California, USA, in 2003. Our focal species set included coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), bobcat (Lynx rufus) and striped skunk (Mephitis mephitis). We evaluated the influence on species occupancies of the burned environment (burn edge, burn interior and unburned areas), proximity of rural homes, distance to riparian area and elevation. Gray fox occupancies were the highest overall, followed by striped skunk, coyote and bobcat. The three species considered as habitat and foraging generalists (gray fox, coyote, striped skunk) were common in all conditions. Occupancy patterns were consistent through time for all species except coyote, whose occupancies increased through time. In addition, environmental and anthropogenic variables had weak effects on all four species, and these responses were species-specific. Our results helped to describe a carnivore community exposed to frequent fire and rural human residences, and provide baseline data to inform fire management policy and wildlife management strategies in similar fire-prone ecosystems.

Detecting Rodents in the Presence of Land Crabs: Indicator Blocks Outperform Standard Rodent Detection Devices at Palmyra Atoll

Author(s): Oberg, Erik; Alifano, Aurora; Pott, Madeleine; Wegmann, Alex | Abstract: Indicator blocks, also called “chew-tag-cards,” made from a small square of corrugated plastic partially filled with an attractant, are an established rodent detection tool used in many different settings. Here, we discuss the utility of indicator blocks in detecting the presence of rats at Palmyra Atoll National Wildlife Refuge (Palmyra) in the Northern Line Islands. The detection of invasive rodents, in this case black rats, can be challenging in the presence of non-target species that may interfere with detection devices. Palmyra supports a robust community of land crabs. Five of the 7 species of land crabs found at Palmyra routinely interfere with commonly-used rodent detection devices: snap traps, live-capture traps, tracking tunnels, motion-sensing cameras, and gnaw sticks. Interference by crabs renders some of the detection methods useless (gnaw sticks) and reduces the sensitivity of others through false triggering (traps and cameras). Coconut crabs, which can exceed 7 kg and are found throughout Palmyra Atoll, can easily destroy tracking tunnels, traps, and even ruggedized motion-sensing cameras. Prior to the successful eradication of rats from the atoll in 2011, we compared the rate of detecting rats using indicator blocks with that of live-capture traps and tracking tunnels in paired, independent samples (90 chew block versus trap samples, 20 chew block versus tracking tunnel samples). Sampling occurred in September and October 2010 and measures were collected consecutively for 19 days. The frequency at which the indicator blocks detected rats was significantly higher (P l 0.001) than that for traps or tracking tunnels, even when interference by land-crabs was minimized by placing the devices on overturned 5-gallon buckets. The results from this study suggest that indicator blocks are an effective and efficient tool for detecting rodents in the presence of non-target species that interfere with rodent detection devices.

Habitat effects on second-order predation of the seed predator Harpalus rufipes and implications for weed seedbank management

Seed predators provide a valuable ecosystem service to farmers by reducing densities of weed seeds, and, in turn, densities of weed seedlings they must manage. The predominant invertebrate weed seed predator in Maine, USA, agroecosystems is the carabid beetle Harpalus rufipes DeGeer. Pitfall trapping has shown that H. rufipes prefers sites with vegetative cover to fallow sites, preference speculated to be driven by predator avoidance behavior. To test this hypothesis, ‘second-order predation assays’ were developed, in which live H. rufipes prey were presented to second-order predators. Field experiments were conducted to determine foremost if H. rufipes was subject to second-order predation, and secondly, whether (a) vegetative cover affords H. rufipes protection from second-order predators, and (b) high rates of second-order predation correspond with decreased invertebrate seed predation rates. Two 72-h experiments were conducted (mid August and September 2012) at crop and non-crop sites across a 28ha diversified farm in Stillwater, ME, USA.Second-order predation was 2.8% per day. Based on images from motion-sensing cameras, H. rufipes’ predators included birds and small mammals. Neither a relationship between second-order predation and vegetative treatment, nor an empirical relationship between second-order predation and invertebrate seed predation were detected. However, a simulation model predicted that 2.8% per day second-order predation could increase the number of seeds entering the seedbank by more than 17% annually. Additionally, complex habitats supported higher rates of second-order predation than did simple habitats.

Flea burden and its influence on nest selection and use in Dryomys nitedula Pallas, 1778

Since dormice usually use natural tree hollows or artificial nest boxes as nest sites and these nests are reused from 1 year to another, the present study investigated how the parasite loads from old nests affected the behaviour of the forest dormouse Dryomys nitedula Pallas, 1778. Dormice were subjected to three different experiments: 1. They were given the choice of a nest box infected with ectoparasites and a new unused nest box; 2. Dormice were given the choice of a treated (uninfected) previously used nest boxes and previously used nest box that was infected; and 3. Using infrared motion sensor cameras, we tested weather they preferred to avoid nest boxes when only infected nests were available. The results revealed that the females with pups are pickier when choosing the nursery site. These preferred empty nest boxes or nest boxes with treated nests instead of the infested ones. However, non-breeding adults and sub-adults showed indifference to the flea infestation of the nest.

Does artificial light influence the activity of vertebrates beneath rural buildings?

Interactions between humans and wildlife have increased dramatically over the past century as human populations increase and occupy areas formerly dominated by native animals. In Australia, increases in land clearing and farming close to riparian areas has brought humans into contact with the common wombat (Vombatus ursinus), a relatively large-bodied, semifossorial marsupial. The common wombat is regarded as a pest in some agricultural areas due to its habit of burrowing beneath buildings, destroying fences and destabilising stream banks. We examined the effectiveness of artificial lighting to deter wombats from using the subfloor cavity under an historic cottage at ‘Bundanon’ in southern New South Wales, Australia. The response of wombats to artificial light (10 weeks on followed by 10 weeks off) was assessed using heat- and motion-sensing cameras continuously over a period of 58 weeks. While the main focus was on light effects on wombats, the study also allowed us to record non-nuisance animals using the subfloor cavity. Of the total of 1086 animal detections over the 58-week period (2.67 detections day–1), 965 (89%) were of mammals, 106 birds and 15 reptiles. Wombats (622; 57%) and kangaroos (228; 22%) made up 79% of all detections. Nocturnal activity of wombats remained unchanged in response to lighting (on: 266; off: 268), but there were significantly more diurnal detections when the lights were on (58) than off (30). For kangaroos, there were more nocturnal detections when lights were off, but more diurnal detections when lights were on. More antechinus were detected at night (night: 107; day: 8), and with the lights off (99 cf. 8), and insectivorous birds were detected almost entirely during the day, mostly with the lights on (66 cf. 39). Our study showed that, overall, the lighting regime we used was ineffective at reducing wombat activity under the building.

Wildlife Passage in Snohomish County: September 2010 to April 2011

Wildlife constitutes a vital, but often unseen, component of Western Washington ecosystems. Wildlife tracking and motion sensor cameras offer a window into the secretive life of animals as they intersect with our roads and highways. The Learn and Serve Environmental Anthropology Field (LEAF) School at Edmonds Community College, in collaboration with Snohomish County Public Works, instituted a formal wildlife-monitoring project in September 2010. This report summarizes data collected through April 2011 at four wildlife corridor sites in Snohomish County. At two sites, Granite Falls Alternative Route and Bridge 600 over Swamp Creek, students monitored newly constructed wildlife passage structures. At two other sites, Bridge 42 over Jim Creek and the 180th and 51st Ave SE Brightwater Culverts, students conducted pre-construction monitoring where wildlife passage structures have been proposed. The data collected to date clearly demonstrates that targeted species are using the newly constructed passage structures and that wildlife passage is needed at the proposed construction sites.

Large-scale rodent control reduces pre- and post-dispersal seed predation of the endangered Hawaiian lobeliad, Cyanea superba subsp. superba (Campanulaceae)

Large-scale rodent control can help to manage endangered species that are vulnerable to invasive rodent consumption. A 26 ha rodent snap-trap grid was installed in montane forest on Oahu Island, Hawaii, in order to protect endangered snails and plants. To assess the effectiveness of this trapping operation in reducing fruit consumption and seed predation of the endangered Hawaiian lobeliad, Cyanea superba subsp. superba, pre- and post-dispersal C. superba fruit consumption were monitored for 36 plants at the site with rodent control (Kahanahaiki) and 42 plants at an adjacent site without rodent control (Pahole). Over 47 % of all monitored fruit were eaten on the plants at Pahole compared to 4 % at Kahanahaiki. Images captured using motion-sensing cameras suggest that black rats (Rattus rattus) were the only pre-dispersal fruit consumers. To quantify post-dispersal fruit consumption, and to identify the culprit frugivore(s), mature fruit were placed in tracking tunnels positioned on the forest floor and checked daily. At Pahole, all of the fruit were consumed by rats compared to 29 % at Kahanahaiki. Lastly, to determine if rodents from the sites were predators or dispersers of C. superba seed, fruit were fed to captive black rats and house mice (Mus musculus). Black rats consumed entire fruit, killing all the seed, while mice did little damage to the fruit and seed. Therefore, large-scale rat trapping can directly benefit the reproduction of C. superba subsp. superba. Controlling black rats at restoration sites appears integral to the successful restoration of this endangered plant species.

Sarcoptes mange (Sarcoptes scabiei) increases diurnal activity of bare-nosed wombats (Vombatus ursinus) in an agricultural riparian environment

Sarcoptes mange is an important disease that affects the health, mobility and longevity of bare-nosed wombats (Vombatus ursinus) in Australia. We measured the activity patterns of wombats infected with varying levels of mange in an agricultural riparian environment using motion-sensing cameras. Over a 10 month period we observed a greater increase in nocturnal activity of mange-free wombats than those with mange on six or more body sections. The percentage of mange-infected wombats was greater during the day, but in the 6h after midnight, wombats were detected with fewer mange-infected segments. Air temperature at the time of wombat detections was generally higher for individuals with mange than those without mange. Our results show that diurnal activity of wombats is likely to increase with higher levels of infection by sarcoptes mange. Increased diurnal activity is likely to present serious problems for the persistence of sustainable populations of wild wombats.

Circadian activity and nest use of Dryomys nitedula as revealed by infrared motion sensor cameras

Circadian activity and nest use of <i>Dryomys nitedula</i> as revealed by infrared motion sensor cameras

Diel Use of Water by Reintroduced Bighorn Sheep

Water sources are an important habitat component for populations of bighorn sheep (Ovis canadensis), and the technique of sampling at water sources has been used extensively to study behaviors and estimate parameters of bighorn populations, Little is known, however, concerning the time of day at which groups of bighorns visit water. Understanding when bighorns visit water sources will allow wildlife investigators to conduct sampling when bighorns are most likely to be present at this resource. We quantified use of 7 water sources by reintroduced bighorn sheep during summer 2005 and 2006 on Antelope Island State Park, Utah. Our purpose was to determine if female, male, or mixed-sex groups visited water at a particular time and if visits to this resource by all bighorns differed in time during drought conditions compared with nondrought conditions. The mean time that all bighorns visited water was 14:22 (s = 3:08 hours). No time differences existed among female, male, or mixed-sex groups or between drought and nondrought conditions. Our results provide wildlife investigators with a time frame for activating motion-sensor cameras or sampling at water sources, which will increase the likelihood of photographing or observing reintroduced Rocky Mountain bighorn sheep at water sources in portions of the Great Basin Desert.

Chukar Watering Patterns and Water Site Selection

Abstract We evaluated chukar (Alectoris chukar) watering patterns as well as habitat variables influencing water site selection in western Utah. Motion-sensing cameras and chukar dropping counts were primary techniques to evaluate watering patterns. We took vegetative and other habitat measurements at each water source (n = 43) to discriminate use from nonuse sites using logistic regression. Chukars watered during daylight hours with a modal hour from 1200 hours to 1300 hours daylight savings time. Annual patterns suggest limited use of water sources from November to May with first observed visits occurring in June and last observed visits in October. Shrub canopy cover was the only variable to discriminate between site types (P 0.05). Chukars seem to have a loose shrub canopy threshold near 11% that is likely due...

Brodifacoum Poisoning of Avian Scavengers During Rat Control on a Seabird Colony

Langara Island, at the north-western tip of British Columbia's Queen Charlotte archipelago, was once nesting grounds for an estimated 500,000 seabirds. However, infestations of Norway rats (Rattus norvegicus) and their predation of eggs and breeding adults have caused extirpation or serious declines of all seabird species. By 1993, the breeding population of ancient murrelets (Synthliboramphus antiquus) had declined to 10% of its historical size. Successful eradication of rats on smaller New Zealand islands using the anticoagulant brodifacoum prompted its application on Langara Island. The island is also home to breeding bald eagles (Haliaeetus leucocephalus), peregrine falcons (Falco peregrinus), and other wildlife. No comprehensive studies of non-target impacts and potential for secondary poisoning were done during similar operations elsewhere; thus, in 1994 and 1995 we initiated a two-year study into the risk of secondary poisoning to non-target species. During 1994, rat carcasses were laid out with motion sensor cameras to identify potential scavengers. Ravens, northwestern crows and bald eagles were photographed at carcasses, and therefore at risk of feeding on rats that die above ground. During the baiting program, 19 rats were radio-tagged to determine the proportion dying above ground, and thus available to predators/scavengers. Ravens were found poisoned both from feeding directly on the bait, and predating/scavenging poisoned rats. Bald eagles were trapped and blood sampled for brodifacoum residue analysis and prothrombin time evaluation; 15% of the sampled population showed detectable residues but no adversely-affected birds were found. We conclude that the use of brodifacoum for rat removal on seabird islands poses a clear risk of secondary poisoning to avian scavengers. This risk must be weighed against the benefit of rat removal programs.