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1.
Ecohealth ; 21(1): 1-8, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38748281

ABSTRACT

From July 2020 to June 2021, 248 wild house mice (Mus musculus), deer mice (Peromyscus maniculatus), brown rats (Rattus norvegicus), and black rats (Rattus rattus) from Texas and Washington, USA, and British Columbia, Canada, were tested for SARS-CoV-2 exposure and infection. Two brown rats and 11 house mice were positive for neutralizing antibodies using a surrogate virus neutralization test, but negative or indeterminate with the Multiplexed Fluorometric ImmunoAssay COVID-Plex, which targets full-length spike and nuclear proteins. Oro-nasopharyngeal swabs and fecal samples tested negative by RT-qPCR, with an indeterminate fecal sample in one house mouse. Continued surveillance of SARS-CoV-2 in wild rodents is warranted.


Subject(s)
Animals, Wild , COVID-19 , Cities , Animals , Mice , Rats/virology , COVID-19/epidemiology , Animals, Wild/virology , SARS-CoV-2 , Peromyscus/virology , Feces/virology , Rodent Diseases/virology , Rodent Diseases/epidemiology , Antibodies, Neutralizing/blood
3.
J Pest Sci (2004) ; 95(1): 79-86, 2022.
Article in English | MEDLINE | ID: mdl-34248453

ABSTRACT

Because rats are commensal organisms that depend on human activities for food, shifts in human behavior will have pronounced effects on local rat populations. In the spring of 2020, social distancing measures were implemented globally to curtail the spread of SARS-CoV-2. This presented a unique opportunity to obtain information regarding the immediate effects of shifts in human behavior on rat populations in a variety of countries. In response to increased sightings of rats in the USA that were reported in American media, we analyzed the changes in the number of public service calls in Tokyo, Japan. We found that the number of calls increased after the implementation of social distancing measures, suggesting that rat sightings had also increased in Tokyo. We then surveyed the changes in the business activities of pest management professionals in the USA, Canada, and Tokyo. We found that the activities were increased in 50 to 60% of the respondents from the USA and Canada. In contrast, 60 to 70% of the respondents from Tokyo answered that their activities were not changed. These results implied that, following the implementation of social distancing measures, rat infestations increased in North America, but not in Tokyo. The survey also suggested that roof rats were considered to be the predominant rodent species in Tokyo. This may account for the limited infestations in Tokyo because roof rats are more sedentary than brown rats. Taken together, our findings suggest that social distancing measures differentially affected rat populations in North America and Tokyo. Supplementary Information: The online version contains supplementary material available at 10.1007/s10340-021-01405-z.

4.
Sci Rep ; 11(1): 22449, 2021 11 17.
Article in English | MEDLINE | ID: mdl-34789796

ABSTRACT

Rodents are among the most successful mammals because they have the ability to adapt to a broad range of environmental conditions. Here, we present the first record of a previously unknown thermal adaptation to cold stress that repeatedly occurred in two species of non-commensal rodents (Apodemus flavicollis and Apodemus agrarius). The classic rodent literature implies that rodents prevent heat loss via a broad range of behavioral adaptations including sheltering, sitting on their tails, curling into a ball, or huddling with conspecifics. Here, we have repeatedly observed an undescribed behavior which we refer to as "tail-belting". This behavior was performed under cold stress, whereby animals lift and curl the tail medially, before resting it on the dorsal, medial rump while feeding or resting. We documented 115 instances of the tail-belting behavior; 38 in Apodemus agrarius, and 77 in Apodemus flavicollis. Thermal imaging data show the tails remained near ambient temperature even when temperatures were below 0 °C. Since the tail-belting occurred only when the temperature dropped below - 6.9 °C (for A. flavicollis) and - 9.5 °C (for A. agrarius), we surmise that frostbite prevention may be the primary reason for this adaptation. It is likely that tail-belting has not previously been documented because free-ranging mice are rarely-recorded in the wild under extreme cold conditions. Given that these animals are so closely-related to laboratory rodents, this knowledge could potentially be relevant to researchers in various disciplines. We conclude by setting several directions for future research in this area.


Subject(s)
Acclimatization/physiology , Behavior, Animal/physiology , Body Temperature Regulation/physiology , Cold-Shock Response/physiology , Tail/physiology , Animals , Cold Temperature , Mice , Poland
5.
J Neurosci Methods ; 362: 109303, 2021 10 01.
Article in English | MEDLINE | ID: mdl-34352335

ABSTRACT

More than 24,000 rodent studies are published annually, with the vast majority of these studies focused on genetically undiverse animals in highly-controlled laboratory settings. However, findings from the laboratory have become increasingly unreliable for predicting outcomes in field and clinical settings, leading to a perceived crisis in translational research. One cause of this disparity might be that most human societies, in contrast to laboratory rodents, are genetically diverse and live in super-enriched environments. Methods for importing wild rats into the laboratory, and also exporting laboratory-style chambers into natural environments are not well-known outside their respective disciplines. Therefore, we have reviewed the current status of supplements to the laboratory rodent assay. We progress logically from highly-controlled experiments with natural breeding colonies to purely naturalistic approaches with free-ranging rats. We then highlight a number of approaches that allow genetically-diverse wild rats to be utilized in context-enriched paradigms. While considering the benefits and shortcomings of each available approach, we detail protocols for random sampling, remote-sensing, and deployment of laboratory chambers in the field. As supplements to standardized laboratory trials, some of these assays could offer key insights to help unify outcomes between laboratory and field studies. However, we note several outstanding questions that must be addressed such as: the trade-off between control and context, possible reductions in sample size, ramifications for the 'standardization fallacy', and ethical dilemmas of working with wild animals. Given these challenges, further innovation will be required before supplemental assays can be made broadly-accessible and thus, transferrable across disciplines.


Subject(s)
Laboratories , Animals , Rats
6.
Neurosci Biobehav Rev ; 115: 25-33, 2020 08.
Article in English | MEDLINE | ID: mdl-32439371

ABSTRACT

A better understanding of context in decision-making-that is, the internal and external conditions that modulate decisions-is required to help bridge the gap between natural behaviors that evolved by natural selection and more arbitrary laboratory models of anxiety and fear. Because anxiety and fear are mechanisms evolved to manage threats from predators and other exigencies, the large behavioral, ecological and evolutionary literature on predation risk is useful for re-framing experimental research on human anxiety-related disorders. We review the trade-offs that are commonly made during antipredator decision-making in wild animals along with the context under which the behavior is performed and measured, and highlight their relevance for focused laboratory models of fear and anxiety. We then develop an integrative mechanistic model of decision-making under risk which, when applied to laboratory and field settings, should improve studies of the biological basis of normal and pathological anxiety and may therefore improve translational outcomes.


Subject(s)
Fear , Predatory Behavior , Animals , Anxiety , Anxiety Disorders , Humans
7.
J Med Internet Res ; 21(8): e14587, 2019 08 06.
Article in English | MEDLINE | ID: mdl-31389340

ABSTRACT

BACKGROUND: The provision of acute medical care in rural and remote areas presents unique challenges for practitioners. Therefore, a tailored approach to training providers would prove beneficial. Although simulation-based medical education (SBME) has been shown to be effective, access to such training can be difficult and costly in rural and remote areas. OBJECTIVE: The aim of this study was to evaluate the educational efficacy of simulation-based training of an acute care procedure delivered remotely, using a portable, self-contained unit outfitted with off-the-shelf and low-cost telecommunications equipment (mobile telesimulation unit, MTU), versus the traditional face-to-face approach. A conceptual framework based on a combination of Kirkpatrick's Learning Evaluation Model and Miller's Clinical Assessment Framework was used. METHODS: A written procedural skills test was used to assess Miller's learning level- knows-at 3 points in time: preinstruction, immediately postinstruction, and 1 week later. To assess procedural performance (shows how), participants were video recorded performing chest tube insertion before and after hands-on supervised training. A modified Objective Structured Assessment of Technical Skills (OSATS) checklist and a Global Rating Scale (GRS) of operative performance were used by a blinded rater to assess participants' performance. Kirkpatrick's reaction was measured through subject completion of a survey on satisfaction with the learning experiences and an evaluation of training. RESULTS: A total of 69 medical students participated in the study. Students were randomly assigned to 1 of the following 3 groups: comparison (25/69, 36%), intervention (23/69, 33%), or control (21/69, 31%). For knows, as expected, no significant differences were found between the groups on written knowledge (posttest, P=.13). For shows how, no significant differences were found between the comparison and intervention groups on the procedural skills learning outcomes immediately after the training (OSATS checklist and GRS, P=1.00). However, significant differences were found for the control versus comparison groups (OSATS checklist, P<.001; GRS, P=.02) and the control versus intervention groups (OSATS checklist, P<.001; GRS, P=.01) on the pre- and postprocedural performance. For reaction, there were no statistically significant differences between the intervention and comparison groups on the satisfaction with learning items (P=.65 and P=.79) or the evaluation of the training (P=.79, P=.45, and P=.31). CONCLUSIONS: Our results demonstrate that simulation-based training delivered remotely, applying our MTU concept, can be an effective way to teach procedural skills. Participants trained remotely in the MTU had comparable learning outcomes (shows how) to those trained face-to-face. Both groups received statistically significant higher procedural performance scores than those in the control group. Participants in both instruction groups were equally satisfied with their learning and training (reaction). We believe that mobile telesimulation could be an effective way of providing expert mentorship and overcoming a number of barriers to delivering SBME in rural and remote locations.


Subject(s)
Chest Tubes , Inservice Training , Patient Simulation , Students, Medical , Telemedicine , Thoracostomy/education , Adult , Female , Humans , Male , Medically Underserved Area , Pilot Projects , Program Evaluation , Rural Population , Video Recording , Young Adult
8.
Cureus ; 11(1): e3908, 2019 Jan 17.
Article in English | MEDLINE | ID: mdl-30931181

ABSTRACT

Emergency medicine practitioners frequently encounter acute presentations requiring quick, directed treatment to ensure the best patient outcome. Training residents in the appropriate clinical and procedural skills often proves difficult when treating the patient who is critically unwell. Simulation-based medical education is an effective modality that enables teaching around life-threatening medical conditions in a safe space for learners while avoiding adverse complications for patients. Severe gastrointestinal bleeding is one such condition that emergency medicine practitioners would benefit from encountering first in a simulation environment due to its high rate of morbidity and mortality if not quickly managed appropriately. This report describes a simulated scenario of an undifferentiated patient who is acutely unwell and then becomes hemodynamically unstable secondary to a severe gastrointestinal bleed. Delivery of the case is facilitated by the detailed technical report herein. It contains a stepwise, detailed summary of appropriate learners' actions and suggestions for learning objectives relating to the case.

9.
Cureus ; 11(2): e3995, 2019 Feb 01.
Article in English | MEDLINE | ID: mdl-30989004

ABSTRACT

Immediate diagnosis and management of ST-elevation myocardial infarction (STEMI), a condition resulting from the complete occlusion of a coronary artery, is critical to achieving optimal patient outcomes. This report outlines an acute inferior STEMI simulation which can be used for teaching different levels of learner including novice, intermediate and advanced. It focuses on the presentation, diagnosis, and management of inferior myocardial infarctions. Additionally, it incorporates the advanced cardiovascular life support (ACLS) protocol for more advanced learners and uses the CanMEDS collaborator/communicator role as an adjunct objective for all learners.

10.
J Am Psychiatr Nurses Assoc ; 25(5): 350-359, 2019.
Article in English | MEDLINE | ID: mdl-30688556

ABSTRACT

BACKGROUND: Attention deficit hyperactivity disorders (ADHD) is a neurodevelopmental disorder that affects up to 7% of children, with consequences lasting into adulthood for an indeterminate number of people. Children with ADHD need special interventions that start with effective parenting. Yet parent-education programs are often inappropriate for low-income or single-parent families who lack transportation, availability, or resources to attend. AIMS: We evaluated a remotely administered, 6-week, Six-step Parenting Program (SsPP) at two community health centers in Trenton, New Jersey. METHODS: Eight low-income, single-parent families were selected for participation. The parent/teacher rating scale of ADHD symptoms (SNAP-IV [Swanson, Nolan, and Pelham-IV questionnaire]) was administered pre- and post-application. RESULTS: Six out of 8 (75%) participating parents/guardians perceived improvements in children's symptoms. Completion of SsPP resulted in reduced SNAP-IV values by an average of 12.4% (n = 8), with improvements in 16 of 18 variables. CONCLUSIONS: The remotely administered SsPP may hold promise for parents unable to attend training and deserves further consideration and evaluation.


Subject(s)
Attention Deficit Disorder with Hyperactivity/therapy , Community Health Services/methods , Parenting/psychology , Parents/education , Program Evaluation/methods , Adolescent , Adult , Child , Female , Humans , Male , Middle Aged , New Jersey , Poverty
11.
Cureus ; 11(12): e6273, 2019 Dec 02.
Article in English | MEDLINE | ID: mdl-31903309

ABSTRACT

Healthcare professionals practicing in rural, remote, or resource-restricted areas have little opportunity to practice "high stakes low-frequency" clinical procedures, despite having higher rates of injury-related death than city inhabitants. Availability of clinical skills instructors, the expense of practicing skills, lack of educational sessions, and distance to simulation centres can be a barrier to teaching and skill maintenance, particularly in rural settings. Telesimulation has the potential to overcome these challenges using audio-visual technology to connect rural learners with instructors in simulation centres. Using low-fidelity simulation models allows learners to acquire clinical skills through hands-on practice without risk or fear of harming real patients. Although not as realistic as high-fidelity models, the low-fidelity three-dimensional (3D) printed model for chest tube insertion is cost-effective and easy to set up and use and is a valid tool for teaching the clinical procedure. The purpose of this technical report was to describe the application of low-cost telesimulation to facilitate teaching chest tube insertion to medical students, emergency medicine residents, and doctors working in remote and rural environments.

12.
BMC Res Notes ; 11(1): 212, 2018 Apr 02.
Article in English | MEDLINE | ID: mdl-29606122

ABSTRACT

OBJECTIVES: The welfare of threatened fauna should not be assumed merely because their refuges have been designated with protected status. This is particularly true in geographical areas where social/military events drive an under-reported, but potentially lethal, type of human-wildlife interaction. Waterbirds of Gharana Wetland Conservation Reserve consist mostly of threatened species. However, as occurs globally, 'protected' fauna near contested borders are sometimes affected by military forces. As part of a larger project to document regional avifauna, we report the seasonal status of waterbirds in order to help establish a baseline for comparing conservation of wildlife within contested areas to that of fauna in more secure refuges. We examined 24 avifauna surveys for relationships between seasons, temperature, individuals and species. RESULTS: 28 of 61 waterbird species were rare. We found seasonal variations in individuals (F3,731 = 3.82; P < 0.01) and species (F3,11 = 5.81; P < 0.05) with a major influx in late winter, rather than autumn. Thus, while this sanctuary serves as an over-wintering site, it is also a stop-over site for high-altitude migrations. While providing this baseline, we offer a reminder that the welfare of wildlife in protected areas should be monitored seasonally, with the ongoing threats to their conservation, carefully documented.


Subject(s)
Birds/physiology , Refugium , Warfare , Wetlands , Agriculture/methods , Agriculture/trends , Animals , Birds/classification , Conservation of Natural Resources/methods , Endangered Species , Geography , Humans , India , Pakistan , Population Dynamics , Seasons
13.
Biol Rev Camb Philos Soc ; 93(1): 98-114, 2018 02.
Article in English | MEDLINE | ID: mdl-28444848

ABSTRACT

Fear of predation is a universal motivator. Because predators hunt using stealth and surprise, there is a widespread ability among prey to assess risk from chemical information - scents - in their environment. Consequently, scents often act as particularly strong modulators of memory and emotions. Recent advances in ecological research and analytical technology are leading to novel ways to use this chemical information to create effective attractants, repellents and anti-anxiolytic compounds for wildlife managers, conservation biologists and health practitioners. However, there is extensive variation in the design, results, and interpretation of studies of olfactory-based risk discrimination. To understand the highly variable literature in this area, we adopt a multi-disciplinary approach and synthesize the latest findings from neurobiology, chemical ecology, and ethology to propose a contemporary framework that accounts for such disparate factors as the time-limited stability of chemicals, highly canalized mechanisms that influence prey responses, and the context within which these scents are detected (e.g. availability of alternative resources, perceived shelter, and ambient physical parameters). This framework helps to account for the wide range of reported responses by prey to predator scents, and explains, paradoxically, how the same individual predator scent can be interpreted as either safe or dangerous to a prey animal depending on how, when and where the cue was deposited. We provide a hypothetical example to illustrate the most common factors that influence how a predator scent (from dingoes, Canis dingo) may both attract and repel the same target organism (kangaroos, Macropus spp.). This framework identifies the catalysts that enable dynamic scents, odours or odorants to be used as attractants as well as deterrents. Because effective scent tools often relate to traumatic memories (fear and/or anxiety) that cause future avoidance, this information may also guide the development of appeasement, enrichment and anti-anxiolytic compounds, and help explain the observed variation in post-traumatic-related behaviours (including post-traumatic stress disorder, PTSD) among diverse terrestrial taxa, including humans.


Subject(s)
Animal Communication , Odorants , Predatory Behavior , Research , Animals
14.
Front Public Health ; 4: 132, 2016.
Article in English | MEDLINE | ID: mdl-27471725

ABSTRACT

We detail a five-stage protocol to address physical barriers and experimental limitations that have hindered routine pathogen monitoring of wild rats in urban settings. New York City potentially harbors from 2 to 32 million rats among its 8-million people. However, at a time, when people are most vulnerable to disease from over-crowdedness brought on by increased urbanization of society, the difficulty of studying wild rats has led to a paucity of ecological and epidemiological research. Challenges of safely handling animals and the difficulties of identifying individual animals and the emergence of their respective pathogen loads (timing of infection) have impeded progress. We previously reported a method using radio frequency identification paired with load cell and camera traps to enable the identification of individual animals and subsequent monitoring of the animals' weights (an indicator of health). However, efficient pathogen surveillance requires repeated captures of the same individual in order to isolate and document the emergence of new pathogens, or variations in pathogen load, over time. Most of these barriers are now addressed in our protocol, which is aided by the use of a mobile, outdoor laboratory, followed by incorporation of pheromone-based lures to attract individuals back to active sensors, within a camera trap. This approach allows for the assessment of individual animal health, behaviors under camera, and changing pathogen loads and weights in most urban environments (e.g., financial district, docks, sewers, and residential). Five phases are described and presented: (1) site selection and urban trapping, (2) anesthetization, (3) serological and ectoparasite collection, (4) microchip implantation, and (5) retrapping and luring animals back to active remote sensors. In order to fulfill the unmet call for preemptive pathogen surveillance, public health officials and researchers may wish to adapt, or modify, similar protocols to ensure early detection and monitoring of rat-borne zoonoses, before they become problematic.

15.
Front Neurosci ; 9: 263, 2015.
Article in English | MEDLINE | ID: mdl-26283903

ABSTRACT

When exposed to the odor of a sympatric predator, prey animals typically display escape or defensive responses. These phenomena have been well-documented, especially in rodents, when exposed to the odor of a cat, ferret, or fox. As a result of these experiments new discussions center on the following questions: (1) is a single volatile compound such as a major or a minor mixture constituent in urine or feces, emitted by the predator sufficient to cause defensive reactions in a potential prey species or (2) is a whole array of odors required to elicit a response and (3) will the relative size or escapability of the prey as compared to the predator influence responsiveness. Most predator-prey studies on this topic have been performed in the laboratory or under semi-natural conditions. Field studies could help to find answers to these questions. Australian mammals are completely naïve toward the introduced placental carnivores. That offers ideal opportunities to analyze in the field the responses of potential prey species to unknown predator odors. During the last decades researchers have accumulated an enormous amount of data exploring the effects of eutherian predator odors on native marsupial mammals. In this review, we will give a survey about the development of olfactory research, chemical signals and their influence on the behavior and-in some cases-physiology of prey species. In addition, we report on the effects of predator odor experiments performed under natural conditions in Australia. When studying all these literature we learned that data gained under controlled laboratory conditions elucidate the role of individual odors on brain structures and ultimately on a comparatively narrow range behaviors. In contrast to single odors odor arrays mimic much more the situation prey animals are confronted to in nature. Therefore, a broad range of methodology-from chemistry to ecology including anatomy, physiology, and behavior-is needed to understand all the different (relevant) stimuli that govern and guide the interactions between a predator and its potential prey.

16.
PLoS One ; 6(1): e14549, 2011 Jan 18.
Article in English | MEDLINE | ID: mdl-21267451

ABSTRACT

BACKGROUND: Animals typically show less habituation to biologically meaningful sounds than to novel signals. We might therefore expect that acoustic deterrents should be based on natural sounds. METHODOLOGY: We investigated responses by western grey kangaroos (Macropus fulignosus) towards playback of natural sounds (alarm foot stomps and Australian raven (Corvus coronoides) calls) and artificial sounds (faux snake hiss and bull whip crack). We then increased rate of presentation to examine whether animals would habituate. Finally, we varied frequency of playback to investigate optimal rates of delivery. PRINCIPAL FINDINGS: Nine behaviors clustered into five Principal Components. PC factors 1 and 2 (animals alert or looking, or hopping and moving out of area) accounted for 36% of variance. PC factor 3 (eating cessation, taking flight, movement out of area) accounted for 13% of variance. Factors 4 and 5 (relaxing, grooming and walking; 12 and 11% of variation, respectively) discontinued upon playback. The whip crack was most evocative; eating was reduced from 75% of time spent prior to playback to 6% following playback (post alarm stomp: 32%, raven call: 49%, hiss: 75%). Additionally, 24% of individuals took flight and moved out of area (50 m radius) in response to the whip crack (foot stomp: 0%, raven call: 8% and 4%, hiss: 6%). Increasing rate of presentation (12x/min ×2 min) caused 71% of animals to move out of the area. CONCLUSIONS/SIGNIFICANCE: The bull whip crack, an artificial sound, was as effective as the alarm stomp at eliciting aversive behaviors. Kangaroos did not fully habituate despite hearing the signal up to 20x/min. Highest rates of playback did not elicit the greatest responses, suggesting that 'more is not always better'. Ultimately, by utilizing both artificial and biological sounds, predictability may be masked or offset, so that habituation is delayed and more effective deterrents may be produced.


Subject(s)
Acoustic Stimulation , Habituation, Psychophysiologic/physiology , Animals , Auditory Perception/physiology , Australia , Crows , Macropodidae , Sound
17.
PLoS One ; 5(5): e10403, 2010 May 05.
Article in English | MEDLINE | ID: mdl-20463952

ABSTRACT

BACKGROUND: Whether or not animals habituate to repeated exposure to predator scents may depend upon whether there are predators associated with the cues. Understanding the contexts of habituation is theoretically important and has profound implication for the application of predator-based herbivore deterrents. We repeatedly exposed a mixed mob of macropod marsupials to olfactory scents (urine, feces) from a sympatric predator (Canis lupus dingo), along with a control (water). If these predator cues were alarming, we expected that over time, some red kangaroos (Macropus rufous), western grey kangaroos (Macropus fuliginosus) and agile wallabies (Macropus agilis) would elect to not participate in cafeteria trials because the scents provided information about the riskiness of the area. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the effects of urine and feces independently and expected that urine would elicit a stronger reaction because it contains a broader class of infochemicals (pheromones, kairomones). Finally, we scored non-invasive indicators (flight and alarm stomps) to determine whether fear or altered palatability was responsible for the response. Repeated exposure reduced macropodid foraging on food associated with 40 ml of dingo urine, X = 986.75+/-3.97 g food remained as compared to the tap water control, X = 209.0+/-107.0 g (P<0.001). Macropodids fled more when encountering a urine treatment, X = 4.50+/-2.08 flights, as compared to the control, X = 0 flights (P<0.001). There was no difference in effect between urine or feces treatments (P>0.5). Macropodids did not habituate to repeated exposure to predator scents, rather they avoided the entire experimental area after 10 days of trials (R(2) = 83.8; P<0.001). CONCLUSIONS/SIGNIFICANCE: Responses to urine and feces were indistinguishable; both elicited fear-based responses and deterred foraging. Despite repeated exposure to predator-related cues in the absence of a predator, macropodids persistently avoided an area of highly palatable food. Area avoidance is consistent with that observed from other species following repeated anti-predator conditioning, However, this is the first time this response has been experimentally observed among medium or large vertebrates - where a local response is observed spatially and an area effect is revealed over time.


Subject(s)
Avoidance Learning/physiology , Cues , Dogs/physiology , Macropodidae/physiology , Odorants , Animals , Fear , Macropodidae/psychology , Predatory Behavior/physiology , Recognition, Psychology , Time Factors
18.
BMC Ecol ; 7: 13, 2007 Oct 29.
Article in English | MEDLINE | ID: mdl-17967196

ABSTRACT

BACKGROUND: There is much debate concerning which ecological constraints are the most limiting factors to seedling recruitment in disturbed communities. We provide the first comparison between selective herbivory and plant competition effects among two post-mined forest ecosystems (primary succession) and one post-fire woodland ecosystem (secondary succession). Animal exclosure assessments of nine common species across eight sites were performed for comparison within three locations separated by up to 200 km. Additionally, we asked whether pre-browsed plants differed in nutrient content between or within species in the separate systems. RESULTS: Among the nine common species, seven of these were affected by mammal herbivory while five shared a similar vulnerability to predation regardless of system. One species was limited by competition (planting density). There was a strong linear correlation between herbivore selectivity (% browsed) and impact (biomass loss) on the fertilized minesites, but not post-fire sites. Phosphorus and potassium were higher for most species in the post-mined system. Principal components analyses revealed that nutrients in shortest supply may be the most likely components of selection within each system. Among all locations, species with highest levels of phosphorus, ADF and leaf water content were often favoured, while high tannins and nitrogen content were generally selected against. CONCLUSION: Herbivory, rather than seedling competition, was the limiting factor for plant performance among post-fire and post-mined reclamation areas. The post-fire seedlings were smaller and more water and nutrient limited, nevertheless browsing prevalence was equivalent at all locations with nearly all seedlings predated. Kangaroo density in the post-fire community declined from the beginning of the experiment, while numbers in the post-mined revegetation increased fourfold within one year. Differences in water and nutrient availability may explain why herbivores are more likely to be attracted to post-mined communities.


Subject(s)
Ecosystem , Fires , Mammals/physiology , Mining , Seedlings , Animals , Biomass , Feeding Behavior
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