How varying pest and trap densities affect Tribolium castaneum capture in pheromone traps

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is an important insect pest in food processing facilities. Pheromone trapping is frequently used to monitor red flour beetle populations in structures; however, the optimal trap density and the relationship between trap captures and beetle density is not known. Two experiments were performed concurrently in environmentally controlled 30‐m² walk‐in chambers to determine the relationship between aggregation pheromone trap captures of red flour beetles and beetle and trap number. In one experiment, beetle density was kept constant at 200 individuals per chamber while trap number was varied from 1 to 8, and in the other experiment trap number remained constant at one per chamber while beetle density varied from 20 to 800 individuals. Results indicated that approximately one out of 23 red flour beetles were captured in a trap. Number of beetles captured in traps increased significantly as beetle density increased; however, the proportion of beetles captured remained consistent across beetle densities with a mean of 4.7 ± 0.6% of individuals captured. Trap captures varied significantly with trap placement within experimental chambers, indicating that subtle differences in the trapping environment can influence trap captures. Data suggested that trap densities of 0.07–0.10 m^?2 (2–3 traps per chamber) would maximize trap capture, whereas a trap density of 0.13 m^?2 (four traps per chamber) would maximize the predictive ability of a trapping equation estimating beetle density from trap captures. Results provide information needed to more thoroughly explore how environmental factors might influence red flour beetle trap capture in the absence of changes in beetle density. Further understanding of these relationships will allow for more accurate assessments of absolute beetle density from pheromone trap capture data.     

Comparison of reptile sampling in Iran with pitfall versus double-ended funnel traps

In north Khorasan province, Iran, we compared the effectiveness of two types of traps for collecting reptiles: funnel traps and pitfall traps. Three stations were monitored over three 10-day periods and in total 544 individuals (including 200 recaptures) belonging to 5 species and 4 families of lizards (Lacertidae) were collected. Funnel traps with 280 captures were more efficient than pitfall traps with 264 captures, but the differences between the two traps are not significant. Three species were captured most often in the three different stations respectively: station 1, Bunopus crassicauda (22% relative frequency); station 2, Eremias fasciata (29% relative frequency); and station 3, Trapelus agilis (32% relative frequency). Shannon species richness indices were higher for pitfall than funnel traps (i.e., 1.45 vs. 1.40), but the difference was not significant. Pitfall traps were better for capturing species that search widely for food, while the funnel traps preferentially captured species that climb plants, such as Trapelus agilis. We recommend using both types of trap to capture the various types of species in any one region.     

Habitat associations of opossums and rodents in a lowland forest in French Guiana

Opossums and rodents were sampled by live-trapping at Paracou, French Guiana to study habitat use. Tomahawk and Sherman traps were placed on the ground and at various heights in the subcanopy and canopy. We captured 10 species of opossums and seven species of rodents. We measured 14 microhabitat variables at each of 485 sampling stations. Presence or absence at a trap station of the three most abundant species of opossums (Didelphis albiventris, Didelphis marsupialis, and Micoureus demerarae) and two rodents (Oecomys rutilus and Proechimys cuvieri) were related by logistic regression analysis to the microhabitat variables. All five species were associated with at least one habitat variable. Linear analysis of categorical data was used to determine the degree of arboreality. Didelphis marsupialis and P. cuvieri were more commonly captured on the ground, D. albiventris was equitably distributed between ground and arboreal traps, and the remaining species were mostly arboreal. Linear analysis was used to compare the distribution of arboreal captures among two substrate types, two heights, and two substrate diameters. Oecomys rutilus was more commonly captured on lianas, D. albiventris and O. rutilus were more commonly captured at lower heights, and D. marsupialis demonstrated a preference for larger arboreal substrates.     

Studies on the effects of bait and sampling intensity on trapping and estimating Wood mice, Apodemus sylvaticus

The effects of baiting a Longworth trap with whole oats and the density of traps on an area, or sampling intensity, on trapping and estimating Wood mice were studied on two neighbouring woodland plots in November 1971. Standard capture-mark-recapture (CMR) methods were used for two weeks followed by five nights of removal trapping.
The presence of bait significantly increased the likelihood of capturing marked and unmarked animals. By increasing the sampling intensity a greater proportion of the population was sampled, although the number of animals captured per trap night decreased. These results have been related to the "effective" number of traps on an area.
Observations on population structure, weather, movement and capturing marked and unmarked animals have been made. CMR population estimates closely resembled the cumulative number of individuals captured in each study and were for the main part lower than the estimates from the removal trapping carried out at the end of the studies.     

Monitoring stink bugs (Hemiptera: Pentatomidae) in mid-Atlantic apple and peach orchards

Pyramid traps coated with "industrial safety yellow" exterior latex gloss enamel paint and baited with Euschistus spp. aggregation pheromone, methyl (2E,4Z)-decadienoate captured more stink bugs than all other baited and unbaited trap types in both apple and peach orchards in 2002 and 2003. Commercial sources of dispensers of methyl (2E,4Z)-decadienoate deployed in association with pyramid traps had a significant impact on trap captures. Captures in pyramid traps were four-fold greater when baited with lures from IPM Technologies, Inc. (Portland, OR) than with lures from Suterra (Bend, OR). Variation in yellow pyramid trap color ("industrial safety yellow" and "standard coroplast yellow") and material (plywood, plastic, and masonite) did not affect trap captures. Brown stink bug was the predominant species captured (58%), followed by dusky stink bug, Euschistus tristigmus (Say) (20%); green stink bug, Acrosternum hilare (Say) (14%); and other stink bugs (Brochymena spp. and unidentified nymphs) (8%). Captures in baited pyramid traps were significantly correlated with tree beating samples in both managed and unmanaged apple orchards and with sweep netting samples in the unmanaged apple orchard. However, problems associated with trapping mechanisms of pyramid trap jar tops and jar traps likely resulted in reduced captures in baited traps. Improved trapping mechanisms must be established to develop an effective monitoring tool for stink bugs in mid-Atlantic orchards.     

Performance of light‐emitting diode traps for collecting sand flies in entomological surveys in Argentina

The performance of two light‐emitting diode traps with white and black light for capturing phlebotomine sand flies, developed by the Argentinean Leishmaniasis Research Network (REDILA‐WL and REDILA‐BL traps), were compared with the traditional CDC incandescent light trap. Entomological data were obtained from six sand fly surveys conducted in Argentina in different environments. Data analyses were conducted for the presence and the abundance of Lutzomyia longipalpis, Migonemyia migonei, and Nyssomyia whitmani (106 sites). No differences were found in presence/absence among the three types of traps for all sand fly species (p>0.05). The collection mean of Lu. longipalpis from the REDILA‐BL didn´t differ from the CDC trap means, nor were differences seen between the REDILA‐WL and the CDC trap collection means (p>0.05), but collections were larger from the REDILA‐BL trap compared to the REDILA‐WL trap (p<0.05). For Mg. migonei and Ny. whitmani, no differences were found among the three types of traps in the number of individuals captured (p>0.05). These results suggest that both REDILA traps could be used as an alternative capture tool to the original CDC trap for surveillance of these species, and that the REDILA‐BL will also allow a comparable estimation of the abundance of these flies to the CDC light trap captures. In addition, the REDILA‐BL has better performance than the REDILA‐WL, at least for Lu. longipalpis.     

Monitoring plum curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), populations in apple and peach orchards in the mid-Atlantic

We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to four trap types in commercial and unsprayed apple and peach orchards. Trap types included black pyramid and clear Plexiglas panel traps deployed outside the orchard 2 m from the border row, and branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. Bait treatments evaluated in conjunction with each trap type included the synthetic fruit volatile benzaldehyde, the aggregation pheromone grandisoic acid (GA), benzaldehyde in combination with GA, and an unbaited control treatment. In commercial apple orchards, significantly more plum curculio were captured in traps baited with benzaldehyde + GA compared with traps baited with other treatments. Furthermore, significantly more plum curculio were captured by screen traps baited with benzaldehyde + GA compared with unbaited control traps. Significantly more plum curculio were captured by screen traps compared with other trap types in an unsprayed apple orchard. Very few captures were recorded in commercial peach orchards. Dissections of trapped females indicate that bivoltine populations are present in the mid-Atlantic. In general, correlations between timing and amount of trap captures and timing and amount of fruit injury inflicted concurrently or 1 wk after trap captures were very weak for all trap types and bait combinations. Our results agree with previous studies in the northeastern United States in which trap captures are increased by presence of semiochemical baits but fail to serve as reliable tools to determine need for and timing of insecticide application against plum curculio.     

Comparison of sex pheromone traps for monitoring pink hibiscus mealybug (Hemiptera: Pseudococcidae)

The pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), is a highly polyphagous pest that invaded Florida in 2002 and has recently been reported from several locations in Louisiana. Although identification of its sex pheromone in 2004 improved monitoring capabilities tremendously, the effectiveness and efficiency of different pheromone trap designs for capturing males has not been evaluated. We deployed green Delta, Pherocon IlB, Pherocon V, Jackson, and Storgard Thinline traps in Homestead, FL, and compared the number of male M. hirsutus captured per trap, the number captured per unit of trapping surface area, the amount of extraneous material captured, and the time taken to count trapped mealybugs. Pheromone-baited traps with larger trapping surfaces (green Delta, Pherocon IIB, and Pherocon V) captured more males per trap than those with smaller surfaces (Jackson and Storgard Thinline), and fewest males were captured by Storgard Thinline traps. However, Jackson traps captured as many or more males per square centimeter of trapping surface as those with larger surfaces, and the time required to count males in Jackson traps was significantly less than in green Delta, Pherocon IIB, and Pherocon V traps. Although all trap designs accumulated some debris and nontarget insects, it was rated as light to moderate for all designs. Based on our measures of effectiveness and efficiency, the Jackson trap is most suitable for monitoring M. hirsutus populations. Additionally, unlike the other traps evaluated, which must be replaced entirely or inspected in the field and then redeployed, only the sticky liners of Jackson traps require replacement, enhancing the efficiency of trap servicing.     

Design and evaluation of traps for Idiarthron subquadratum (Orthoptera: Tettigoniidae) with farmer participation in coffee plantations in Chiapas, Mexico

Three new types of traps designed and made by farmers were evaluated for capture of Idiarthron subquadratum Saussure & Pictet. Bag, sack, and fabric traps were compared with previously used bamboo internode traps. A participatory methodology was used involving farmer interviews and workshops to design and make the traps. Farmer participation was useful for obtaining information on perceptions, knowledge, and control activities of I. subquadratum. The bag trap captured a greater number of individuals than the bamboo and fabric traps, but its captures were similar to those of sack trap; captures were similar in bamboo, sack, and fabric traps. When captured individuals were analyzed by stage of development, no significant differences between types of traps were detected for captured adults. The number of individuals captured in the traps showed a similar trend to that counted in nocturnal sampling. A significant positive relationship was detected between numbers of adults captured and the damage of leaves and fruits. Taylor's Power Law indicates that I. subquadratum individuals were more abundant in some traps than in others. With densities greater than five individuals per trap, a smaller number of bag traps was required to estimate the same population compared with the other types of traps. Sampling procedure that used the bag traps had the lowest cost. This study shows that resource-poor coffee, Coffea arabica L., farmers had accumulated knowledge of I. subquadratum based on unpublished data and experience and that they were capable of applying this knowledge to develop an economical and more suitable technology for their conditions.     

Comparison of mating disruption and mass trapping with Pyralidae and Sesiidae moths

Mating disruption and mass trapping for control of lepidopteran pests use synthetic sex pheromone to prevent males from finding and mating with females. Here, we identify the behavioral mechanism underlying mating disruption and mass trapping of American plum borer, Euzophera semifuneralis (Walker) (Lepidoptera: Pyralidae), peachtree borer, Synanthedon exitiosa Say, and lesser peachtree borer, Synanthedon pictipes (Groeten) (Lepidoptera: Sesiidae). In addition, we derive relative dispenser activity (Relative D_a) from the competitive attraction equation to compare the disruptive activity of the devices used in mating disruption and mass trapping. Dispensers and traps were deployed in replicated 0.14‐ha cherry or peach plots with E. semifuneralis or the Synanthedon moths, respectively. Dispenser densities were 0, 10, 20, 59, 185, and 371 per ha, whereas trap densities were 0, 10, 20, 40, 79, and 158 per ha. Moth catch in a centrally placed, pheromone‐baited monitoring trap in each plot was used to evaluate the treatments. The profile of moth captures in mating disruption and mass trapping with the three species indicates that competitive attraction is the behavioral mechanism responsible for trap disruption. Relative D_a is 0.27, 0.23, and 0.53 with American plum borer, peachtree borer, and lesser peachtree borer, respectively, which indicates that the traps are 1.9–4.4 times more effective in reducing moth catch than the dispensers. Relative D_a can be used to compare devices for pheromone‐based behavioral manipulation of these and other species that are competitively attracted to artificial pheromone sources. When the same type of trap is employed for monitoring and mass trapping, Relative D_a is the same as dispenser activity D_a.     

Influence of trap type, trap colour, and trapping location on the capture of the pine moth, Thaumetopoea pityocampa

Studies were conducted to evaluate the effect of type, location, and colour of traps baited with 1 mg of the sex pheromone (Z)‐13‐hexadecen‐11‐ynyl acetate in polyethylene vials on the capture of the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermüller) (Lepidoptera: Thaumetopoeidae), males. The experiments were carried out during two flight seasons in 2002 and 2003 at a low elevation Mediterranean pine forest on the hill of Goritsa (Magnesia, Thessaly, Central Greece). The hill is covered by approximately 120 ha of pines, among which Pinus brutia Ten. (Pinaceae) is predominant with Pinus halepensis Mill. (Pinaceae) as second most common species. Among the commercially available trap types used, the Delta and Pherocon II captured significantly more males than the Funnel trap. Furthermore, pine density had a significant effect on trap type and trap colour catches. Delta traps caught significantly more adults than the other two trap types in the low density pine stand, while in the medium and high‐density pine stands no significant differences were noted between Delta and Pherocon II traps. In addition, trap colour performance varied according to pine density; white‐ and yellow‐coloured traps caught significantly more males than the other two trap colours in the high‐density stand. The first adults were captured in traps during May, and traps continued to capture adults in low numbers (< two individuals per trap) until mid‐June. A period of 3–4 weeks of no trap captures followed until mid‐July, when captures restarted, at low numbers. The peak of T. pityocampa flight was observed during late August–September.     

Impact of trap design, windbreaks, and weather on captures of European corn borer (Lepidoptera: Crambidae) in pheromone-baited traps

Pheromone-baited traps are often used in ecological studies of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae). However, differences in trap captures may be confounded by trap design, trap location relative to a windbreak, and changes in local weather. The objectives of this experiment were, first, to examine differences in 0. nubilalis adult (moth) captures among the Intercept wing trap, the Intercept bucket/funnel UNI trap, and the Hartstack wire-mesh, 75-cm-diameter cone trap (large metal cone trap) as well as among three cone trap designs. Second, we examined the influence of the location of the large metal cone trap relative to a windbreak on the number of moths captured. Third, we examined the relationship between nightly mean air temperature, relative humidity, wind speed, precipitation, and the number of moths captured in large metal cone traps. The number of moths captured was significantly influenced by trap design, with large metal cone traps capturing the most moths. Wing and bucket traps were ineffective. Differences among trap captures were significant among trap locations relative to a windbreak. Under strong (>14 kph) or moderate (7 <14 kph) wind speeds, traps located leeward of the windbreak captured the most moths, but when wind speeds were light (<7 kph), traps not associated with windbreaks captured the most moths. The multiple regression model fitted to the relationship between number of moths captured per Julian date and nightly weather patterns was significant. Nightly mean air temperature was the most influential parameter in the model, and its relationship with moth capture was positive.     

Comparison of different trapping methods for surveillance of mosquito vectors of West Nile virus in Rhône Delta,France

Five trapping methods were compared for monitoring potential vectors of the West Nile virus in four areas in the Camargue Plain of France: carbon dioxide traps, bird‐baited traps, gravid traps, resting boxes, and human landing catches. A total of 73,721 specimens, representing 14 species, was trapped in 2006. Results showed significant differences in species and abundance between the type of traps. Many more specimens were collected using CO₂ traps than any other method, with an average of 212 specimens per night per trap (p<0.05). Culex pipiens was the most abundant species collected (36.8% of total with CO₂ traps), followed by Aedes caspius (22.7%), Anopheles hyrcanus (18.3%), Culex modestus (18.3%), and Aedes detritus (3.2%). Bird‐baited traps captured only eight specimens per night per trap on average, mainly Cx. pipiens (89.9%). The species collected and their abundance are influenced by the trap location, at ground or canopy level. Culex pipiens was twice as abundant in the canopy as on the ground, whereas it was the opposite for Ae. caspius, An. hyrcanus, and Ae. detritus. Culex modestus was equally abundant at both levels. Resting boxes and gravid traps were much less efficient, capturing around 0.3 specimens per night per trap. Results are discussed in relation to West Nile virus surveillance.     

Development and comparison of trunk traps to monitor movement of Halyomorpha halys nymphs on host trees

Halyomorpha halys Stål (Hemiptera: Pentatomidae) has recently become a major orchard pest in the Mid‐Atlantic, USA. Large H. halys populations can develop on wild tree hosts adjacent to orchards, posing an ongoing threat to fruit. Adults and nymphs feed on tree fruit, causing economic injury. Understanding the seasonal patterns of nymphal host use among trees at the orchard‐woodland interface may aid the development of integrated pest management strategies for this pest. In laboratory and field experiments, modified versions of published trap designs – ‘Circle’, ‘Hanula’, ‘M&M’ (after Moeed & Meads) traps – were compared for their effectiveness for capturing H. halys nymphs walking up and down tree trunks. In the laboratory, second instars were released at the top and bottom of ailanthus (tree of heaven), Ailanthus altissima (Mill.) Swingle (Simaroubaceae), logs and captures were recorded after 24 h. Circle and M&M traps, respectively, were most effective for capturing nymphs walking up and down. In the field, traps were deployed on ailanthus trees next to apple orchards and captures were recorded weekly from 24 July to 11 September 2013. As in the laboratory, Circle and M&M traps captured the greatest number of upward‐ and downward‐walking nymphs. Hanula traps were least effective in both experiments. In the field, 88% of total captures were of nymphs walking up trees. This was at least partially explained by behavioral assays in the laboratory demonstrating that nymphs exhibited negative gravitaxis and positive phototaxis. Stage‐specific trends in captures of instars walking up during field sampling were observed. These results suggest that trunk traps can be used to address important ecological questions about seasonal patterns of host use by H. halys nymphs.     

Species characterization and responses of subcortical insects to trap‐logs and ethanol in a hardwood biomass plantation

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A portable,remote‐controlled nest‐box trap

Many researchers catch adult birds at nest boxes using a vertical prop that supports a horizontal flap that drops down when an adult enters to feed nestlings. Because the prop is visible, some birds may be too wary to enter nest boxes, or they may dislodge the prop when they lean in; either way, they are not captured. We describe a remote‐controlled nest‐box trap that has the advantages of portability and being invisible to adults delivering food to nestlings. A receiver is installed on the ceiling of a nest box, the receiver is connected to a spring‐loaded flap that is triggered remotely with a transmitter from > 30 m away, and the flap drops down to cover the box entrance. In 2017 and 2018, our remote‐controlled traps did not increase the likelihood of capturing female Tree Swallows (Tachycineta bicolor), but did improve the likelihood of capturing males. We captured 16 male Tree Swallows in 30 attempts (53.3%) using our remote‐controlled trap compared to only 41 captures of males in 139 attempts (29.5%) with prop traps. In addition, whereas prop traps required an average of ~ 50 min to capture adults in successful attempts, our trap required only ~ 25 min. These results suggest that the savings in time for field researchers using our remote‐controlled trap can be substantial, with the added ethical benefit of reducing the amount of time that nestlings are not being fed. Our remote‐controlled trap is also economical to construct, requiring ~ $60 USD for parts and < 3 h to build.     

Spatial distribution and population composition of the brown mouse lemur (Microcebus rufus) in Ranomafana National Park, Madagascar, and its implications for social organization

Through a 16-mo mark-recapture trap study, I examined aspects of spatial distribution and population composition in the brown mouse lemur, Microcebus rufus, a 42 g nocturnal strepsirhine. The study took place in the rainforest of Ranomafana National Park in southeastern Madagascar. Sherman live traps were set monthly for a variable number of nights in a quasi-grid 50 m apart. Captured individuals were marked for future identification and released at site of capture. More males than females were captured overall (102 versus 72) and at 83% of trap sites. Trap sex ratio fluctuated significantly over the course of the study. It was particularly male-biased between June and August (3.9:1), when more previously uncaptured males than females (14 versus 6) entered the trap population. Some of these males remained in the trap population. Although the average number of individuals captured was not significantly different between the first four and last four months of the study, the composition of the population changed. The female population, however, changed less: 28.9% of all females captured in the first four months of the study were recaptured in the last four months, compared to 9.7% of males. It is suggested that the pattern of appearance of new individuals and disappearance of others, both predominantly male, may indicate migratory activity. Furthermore, an average of eight individuals were captured at each trap site (approximately 70% of traps captured more than five), suggesting a high degree of spatial overlap. The average number of male and female individuals captured in each trap (5.5 males versus 2.5 females), the average number of trap sites at which males and females were captured (3.6 versus 2.4), and the average number of captures for males and females (9.8 versus 5.7) all differed significantly between the sexes.     

Comparative efficacy of five types of trap for woodborers in the Cerambycidae, Buprestidae and Siricidae

1 Traps of four new designs were tested against the conventionally used multiple‐funnel trap to determine whether trapping of large wood‐boring insects can be improved in western Canada. All four new traps used a large collecting receptacle containing detergent‐laced water, and three presented a prominent visual silhouette above the receptacle. 2 In total, 27 336 large woodborers were captured from 10 June to 30 September in an experiment in the southern interior of British Columbia, and 4737 from 6 June to 27 July in an experiment in northern Alberta. The woodborers captured in the British Columbia experiment were mainly beetles in the families Cerambycidae (79%) and Buprestidae (15%), and woodwasps in the family Siricidae (6%). Most woodborers, e.g. three Monochamus spp. and Xylotrechus longitarsus (the predominant cerambycids), were captured throughout the summer, with peak captures in August. 3 Cross‐vane, pipe and stacked‐bottomless‐flower‐pot traps were generally superior to pan and multiple‐funnel traps for insects in nine taxa, but cross‐vane traps were the most effective overall, trapping 32% of all insects captured. 4 The large number of target insects captured in a relatively small number of traps in the two experiments suggests that employment of an efficacious trap with a large vertical silhouette and a wide, escape‐proof collecting receptacle could make mass trapping of large woodborers in timber processing areas operationally feasible. 5 Because the most effective traps were unstable in the wind, and the detergent‐laced water captured unacceptably high numbers of small mammals, design modifications are necessary. We are currently developing a wind‐firm trap, with a prominent vertical silhouette, a wide collecting surface, and an escape‐proof, but dry collecting receptacle.     

Effect of hunger on yellow water trap catches of hoverfly (Diptera: Syrphidae) adults

1 An experiment was conducted in a winter wheat field using yellow water traps at crop height and at ground level, near to and distant from flowers, to test the hypothesis that such traps are seen as a source of food by flower‐feeding adult hoverflies and are therefore likely to selectively trap hungry individuals. Hoverflies caught in each trap were counted and identified and the amount of pollen in their guts was assessed. Ratios of numbers of hoverflies seen in the wheat crop to numbers caught in nearby traps were compared for the different treatments. 2 Most hoverflies were caught in crop‐high traps but they included a high proportion of individuals with empty guts. The taxa were: Episyrphus balteatus (De Geer), Metasyrphus corollae (F.) (these species together accounted for over 90% of the individuals trapped), with Sphaerophoria spp., Syrphus spp., Scaeva pyrastri (L.), Melanostomini and unidentified others making up the rest. 3 Significantly fewer hoverflies were captured in low than in high traps. The ratios of numbers trapped to numbers observed, in flower and in no flower treatments would be expected to be the same if the traps were not selective. This was supported for low traps. With high traps, however, there was a highly significant difference between the ratios (71.34 and 126 : 8, respectively). 4 Flies captured in high traps had less pollen in their gut than those captured in low ones. At each distance, more E. balteatus captured in high traps were in pollen category 1 (< 20 grains) than in any other category. The opposite state was seen in low trap catches, where most flies were in category 5 (> 5000 grains). Median pollen categories were 2 (21–200 grains) and 4 (1501–5000 grains) for flies caught in high and low traps, respectively. 5 The ecological selectivity of traps according to their height and the physiological condition of the targeted individuals is a problem likely to affect many trapping systems apart from the one described in this paper.     

Best Management Practices for Trapping Furbearers in the United States

Humans have used wild furbearers for various purposes for thousands of years. Today, furbearers are sustainably used by the public for their pelts, leather, bones, glands, meat, or other purposes. In North America, contemporary harvest of furbearers has evolved along with trap technologies and societal concerns, and is now highly regulated and more closely coupled with harvest analysis and population monitoring. Traps and regulated trapping programs provide personal or cultural rewards that can also support conservation, and can assist with advancing ecological knowledge through research, protecting endangered species, restoring populations or habitats, protecting personal property, and enhancing public health and safety. However, animal welfare and trap selectivity remain important topics for furbearer management in North America, as they have for more than a century. A related international challenge to modern furbearer management came with the Wild Fur Regulation by the European Union, which passed in 1991. This regulation prohibited use of foothold traps in many European countries and the importation of furs and manufactured fur products to Europe from countries that allowed use of foothold traps or trapping methods that did not meet internationally agreed-upon humane trapping standards. To address existing national concerns and requirements of the Wild Fur Regulation, the United States and European Union signed a non-binding bilateral understanding that included a commitment by the United States to evaluate trap performance and advance the use of improved traps through development of best management practices (BMPs) for trapping. Our testing followed internationally accepted restraining-trap standards for quantifying injuries and capture efficiency, and we established BMP pass-fail thresholds for these metrics. We also quantified furbearer selectivity, and qualitatively assessed practicality and user safety for each trap, yielding overall species-specific performance profiles for individual trap models. We present performance data for 84 models of restraining traps (6 cage traps, 68 foothold traps, 9 foot-encapsulating traps, and 1 power-activated footsnare) on 19 furbearing species, or 231 trap-species combinations. We conducted post-mortem examinations on 8,566 furbearers captured by trappers. Of the 231 trap model-species combinations tested, we had sufficient data to evaluate 173 combinations, of which about 59% met all BMP criteria. Pooling species, cage traps produced the lowest average injury score (common injuries included tooth breakage), with minimal differences across other trap types; species-specific patterns were generally similar, with the exception of raccoons (Procyon lotor) for which foot-encapsulating traps performed better than other foot-restraining trap types. Padded-jaw foothold traps performed better than standard-jaw models for many species, though often similar to and occasionally worse than offset- or laminated-jaw models. Most traps we tested had high capture efficiency; only 5 (3%) failed BMP standards strictly because of poor efficiency. Average furbearer selectivity was high across all trap types we evaluated and was lowest for footsnares (88%) and highest for foot-encapsulating traps (99%). Mortality from trap-related injury in restraining traps we tested was very rare for furbearers (0.5% of animals). In over 230,000 trap-nights across a 21-year period, no individuals of a threatened or endangered species were captured. Of 9,589 total captures, 11% were non-furbearers, of which 83% were alive upon trap inspection; nearly all non-furbearer mortalities were birds, rabbits, or squirrels. Approximately 2% of total captures were feral or free-ranging dogs (Canis familiaris), of which none died or were deemed in need of veterinary care by either our technicians or the owners (if located). Similarly, 3% of total captures were feral or free-ranging cats (Felis catus); 2 were dead, and although locating potential owners was often impossible, none of the remaining cats were deemed in need of veterinary care by technicians or owners. Our results show that furbearer selectivity was high for all trap types evaluated, mortality or significant injury was very rare for domestic (or feral) animals, and the most potential for mortality or injury of non-furbearers was with smaller animals, a majority of which were squirrels and rabbits. Our results suggest that injury scores for a given trap-species combination are unlikely to vary significantly across states or regions of the United States, provided similar methods are employed. Our data also suggest that taxonomic affiliation and body-size groupings are correlated with injury scores, presumably through morphological, physiological, or behavioral adaptations or responses that influence injury potential during restraint; higher injury scores in foot-restraining trap types were more likely in smaller or more dexterous species, whereas injury scores were typically lowest for the felids we evaluated. For some species (e.g., American badger [Taxidea taxus], bobcat [Lynx rufus]), most restraining traps we tested met BMP standards, whereas few restraining traps we tested met standards for other species (e.g., muskrat [Ondatra zibethicus], striped skunk [Mephitis mephitis]). Comparison of our results with survey information collected during 2015 on trap use in the United States indicates that approximately 75% of all target furbearers harvested were taken in BMP-compliant traps, with another 10% taken in traps yet to be tested on that species. Future trap testing and development should focus on commonly used traps not yet tested on a species, species for which few passing traps currently pass BMP criteria, and trap models and modifications most likely to minimize trap injuries given a species morphology, physiology, and behavior. Outreach efforts should focus on general BMP awareness, discouraging use of traps that fail BMP standards for a given species, and public outreach on trapping. Restraining (and other) traps have evolved substantially in recent decades and offer numerous benefits to individuals, conservation, and society. However, continuing to address societal concerns remains a critical component of modern regulated trapping and furbearer management. Published trapping BMPs are regularly updated online and may include additional approved restraining and killing traps that were evaluated as part of testing by Canada. We will periodically update the trap performance tables and figures we presented and make them available online at the Association of Fish and Wildlife Agencies website. Published 2020. This article is a U.S. Government work and is in the public domain in the USA. Wildlife Monographs published by Wiley Periodicals LLC on behalf of The Wildlife Society.