Evaluation of visible implant elastomer as a method for tagging small European eels

Visible implant elastomer (VIE) tagging showed no significant effect on survival of either 230 single-tagged or 60 multiple-tagged small European eels Anguilla anguilla . Mean tag retention was 98·7% during the 5 month laboratory experiments. Multiple VIE tags had no observed effect on European eel locomotor behaviour. VIE appears a reliable method for individually tagging small European eels, and could be useful in capture–recapture field studies.     

Growth,mortality and tag retention of small Anguilla anguilla marked with visible implant elastomer tags and coded wire tags under laboratory conditions

Growth, and potential marking‐related mortality of small European eel Anguilla anguilla (L.) after marking with visible implant elastomer tags (VIE) and coded wire tags (CWT) were investigated over a 6‐month period in a laboratory experiment. In addition, mark retention after marking was examined for another 16.5 months. Neither marking method had a significant effect on growth (P > 0.05) or mortality (P > 0.05). After 32 days detection of the VIE marks implanted on the ventral surface and along the base of the ventral tail fin margin was 98 and 100%, respectively, but decreased to 9 and 66% after 512 days. Retention of the CWT implanted in the dorsal musculature of A. anguilla was 99% after 32 days and did not change by day 512. It was therefore concluded that marking‐induced mortality was nil for both marking types over the 6‐month period. Generally, both methods are found to be suitable for marking young A. Anguilla. VIE tags, however, should be used for short‐time mark‐recapture experiments only, and should be injected at the base of the ventral fin margin. The use of CWTs seems to be the more suitable marking method for long‐term mark‐recapture experiments. Nevertheless, field tests are necessary to evaluate these marking methods.     

Who are we sampling? Apparent survival differs between methods in a secretive species

Survival is a fundamental parameter in population dynamics with increasing importance in the management and conservation strategies of wildlife populations. Survival probability in vertebrates is usually estimated by live‐encounter data obtained by means of physical mark–capture–recapture protocols. Non‐invasive acoustic marking relying on individual‐specific features of signals has been alternatively applied as a marking technique, especially in secretive species. Nevertheless, to date no research has compared survival rate estimates obtained by acoustic and physical marking. We estimated half‐yearly and annual survival and recapture rates of a secretive and threatened passerine, the Dupont's lark Chersophilus duponti, using two separate live‐encounter data sets of males collected simultaneously by physical and acoustic marking in the same study area. The separate analysis of both methods led to different model structures, since transient individuals had to be accounted for in the acoustic marking but not in the physical marking data set. Furthermore, while reencounter probabilities did not differ between methods, survival estimates employing physical marking were lower than those obtained acoustically, especially between the postbreeding and the breeding period when the apparent survival of colour‐banded birds was twice as low as for acoustic marking. The combination of marking methods suggested the existence of different subsets of individuals differentially sampled within the population: whereas colour‐banded males seemed to represent the territorial fraction of the population, both resident and floater individuals were probably detected by acoustic marking. Using traditional mark–recapture methods exclusively could have misled our estimates of survival rates, potentially affecting prospective predictions of population dynamics. Acoustic marking has been poorly applied in mark–recapture studies, but might be a powerful complement to obtain accurate estimates of fundamental demographic parameters such as survival and dispersal.     

Evaluation of VIE and PIT tagging methods for juvenile cyprinid fishes

Retention and mortality associated with visible implant elastomer (VIE) and passive integrated transponder (PIT) tagged juvenile chub [ Leuciscus cephalus (L.)], dace [ Leuciscus leuciscus (L.)] and roach [ Rutilus rutilus (L.)] were evaluated. PIT tag retention (96.6–100%) was higher than VIE over the 6-month duration of the experiment. VIE retention was significantly better in the head (96.3–98.8%) than in the fins (78.8–90.9%) the first month after tagging, but the opposite was found after 6 months (head = 21.5–57.5%; fins = 77.2–88.8%). Survival was not significantly different from controls for any treatment, except dace tagged with 23-mm PIT (significantly influenced by mass of fish at tagging) and sham PIT tagged dace, because of initial losses. PIT tags are recommended as the most suitable method for tagging individual juvenile chub, dace and roach based on high retention and survival. VIE implantation in the head (studies < 30 days) and fins (studies > 30 days) could provide a cheap, batch-marking alternative, provided retention rates are monitored.     

The evaluation of passive integrated transponder (PIT) tags and visible implant elastomer (VIE) marks as new marking techniques for the bullhead

To test the reliability of PIT tags and VIE marks as new marking techniques for the bullhead Cottus gobio , different tagging treatments were assayed. The relatively high recapture rates suggest the applicability of both marking techniques for this small benthic fish species.     

Marking through molts: An evaluation of visible implant elastomer to permanently mark individuals in a lower termite species

1. Advances in individual marking methods have facilitated detailed studies of animal populations and behavior as they allow tracking of individuals through time and space. Hemimetabolous insects, representing a wide range of commonly used model organisms, present a unique challenge to individual marking as they are not only generally small‐bodied, but also molt throughout development, meaning that traditional surface marks are not persistent.
2. Visible implant elastomer (VIE) offers a potential solution as small amounts of the inert polymer can be implanted under the skin or cuticle of an animal. VIE has proved useful for individually marking fish, crustaceans, and amphibians in both field and laboratory studies and has recently been successfully trialed in laboratory populations of worms and fly larvae. We trialed VIE in the single‐piece nesting termite Zootermopsis angusticollis, a small hemimetabolous insect.
3. We found that there was no effect of VIE on survival and that marks persisted following molting. However, we found some evidence that marked termites performed less allogrooming and trophallaxis than controls, although effect sizes were very small.
4. Our study suggests that VIE is an effective technique for marking small hemimetabolous insects like termites but we advocate that caution is applied, particularly when behavioral observation is important.

     

Microdot technology for individual marking of small arthropods

• 1 Individual mark–release–recapture is an important method for gathering data on insect movement, although it is limited by the constraints of tagging small insects with individual information.
• 2 Microdots, originally developed for covert security applications, are small polymer discs (diameter 0.5 mm) bearing up to 26 characters of information and have the potential as an alternative to the larger bee tags. In the present study, we test microdots for the individual marking of a 9‐mm parasitoid wasp.
• 3 We individually marked 505 wasps. The recapture rate was 24% of individuals over 189 recapture events, for which 84% retained legible microdot labels. Movement was in the range 0–161 m with a mean displacement 21.2 ± 2.7 m. A captive survival experiment showed no difference in lifespan between marked and unmarked wasps.
• 4 The present study shows that microdots can provide an effective, durable, low‐cost method for individually tagging small insects. The technique offers new opportunities by greatly expanding the capability for individually marking small insects, shifting the minimum size below that of bee tags, which is the only other manufactured option for individualized miniature marking.

     

Subcutaneous injection of visible implant elastomer in sterlet (Acipenser ruthenus Linnaeus, 1758): a study on compatibility and retention

The purpose of this study was to mark endangered sterlet (Acipenser ruthenus) with visible implant elastomer (VIE) in order to assess mortality, compatibility, retention, persistence and histological reactions resulting from this tagging technique. It was hypothesized there would be only minor effects on the fishes' health, and assumed that acute effects would be more pronounced than long‐term effects. On 11 September 2013, 20 specimens were tagged ventrally with visible implant elastomer, 20 received a subcutaneous injection with 0.9% NaCl solution, and another 20 served as untreated control. Mean total length was 28.0 ± 1.8 cm and mean body mass 64.1 ± 12.0 g. The sterlets were kept in four 4,000‐L tanks filled with 2,400‐L water. Acute effects were monitored for 95 days, where fish were held at temperatures between 2.4°C and 15.2°C, reflecting outdoor conditions. Chronic effects were examined 282 days post‐tagging through histological sections of the tagging region in five sterlets. During the first 95 days of observation, tag retention was 100%. No signs of incompatibility were detected. Body mass did not significantly differ between VIE‐tagged fish and controls. At day 282 post‐tagging, however, distinct tissue reactions were visible at the tagging sites of nine fish. Histological examination of five fish revealed a variable degree of infiltration with leukocytes in the areas around the elastomer, which did not necessarily correspond with the externally visible degree of inflammation. After medical treatment, the lesions healed without complications, whereas the retention rate of the VIE tags was 5%. According to the findings, the tag location rather than the tag itself was responsible for the externally visible irritations, indicating that the ventral subcutis of sterlet is not a suitable site, even for small VIE tags in long‐term studies. The results of this study also suggest that VIE marking should in general be critically evaluated before application in field studies.     

Toe‐bud clipping of juvenile small marsupials for ecological field research: No detectable negative effects on growth or survival

Toe clipping is widely used to permanently mark many species of small vertebrates including marsupials, particularly didelphids and dasyurids. Small marsupials are marked as juveniles, by removing the tip of developing toe buds. It has recently been shown that survival and/or recapture probability decreases with increasing number of toes clipped in frogs. Because of this and other animal welfare concerns, toe clipping of adult vertebrates is increasingly being discouraged. The short‐ and long‐term effects of toe‐bud clipping have not been evaluated in marsupials. We used an experiment to test if marking more toes results in slower growth or higher mortality in the brown antechinus (Antechinus stuartii, Dasyuridae) in the short or long term. We found no harmful effects of toe‐bud clipping. There were no infections associated with clipping, marking more toes did not reduce growth in young or adults, and did not affect survival of young in captivity, survival of independent animals in the wild, or recapture probability. Toe‐bud clipping is done at an extremely immature stage, when the area cut is tiny and perception and memory of pain is unlikely to be a problem. We suggest that toe‐bud clipping is a humane and benign method of permanently marking antechinuses, and probably also the young of other morphologically similar small marsupials.     

Are we overestimating recovery of sturgeon populations using mark/recapture surveys?

Mark‐recaptures studies are often conducted to monitor trends in sturgeon populations. However, many of these studies experience low recapture rates, minimal movement between marking‐recapture phases suggesting that sturgeon as a group are not conducive to mark‐recapture techniques. In this study, two mark‐recapture studies that were conducted differently were reviewed. A study was conducted on the Mattagami River using random nets set throughout the study area in both the mark and recapture phases. The other study was conducted on Lake of the Woods and marked sturgeon in tributaries during the spawning period and the recapture phase within the lake and river during the summer foraging period using random nets sets. Sturgeon's conduciveness to mark‐recapture studies was assessed on the Mattagami River mark‐recapture study by determining detection probability (p) using a hierarchical Bayesian model with data augmentation among three effects: individual effect, temporal effects, and behavioural response effects. Detection probability was constant over individuals and temporally suggesting model M₀ (Otis, Burnham, White, & Anderson, 1978 ) was suitable for lake sturgeon in the Mattagami River; only the M₀ would converge for the Lake of the Woods study. For this study, the assumption that “all individuals have the same probability of being captured during the marking phase” was believed to have been violated given approximately 16%–20% of adult Lake Sturgeon from a population spawn within a year. A population estimate accounting for p provided estimates 56% lower than calculated by a Chapman modification of the Peterson estimate for a closed population. Bias was believed to have been introduced as the Lake of the Woods population did not account for the non‐spawning adults that were encountered during the recapture phase and not vulnerable during the initial marking phase. This was not unique to the Lake of the Woods study as other sturgeon studies, especially multi‐year, assumes a closed population which potentially biased estimates and overestimated their recovery.     

Reappraisal of an old cheap method for marking the European hedgehog

Marking quilled animals for individual recognition may be challenging. This is particularly true for European hedgehogs Erinaceus europaeus, whose defense mechanism involves the concealment of muzzle and underparts. Heat-shrink tubes have been widely used to mark quills, but they do not adapt to the morphological structure of the spines and are rapidly lost, thus reducing method effectiveness. We adapted a cheap and ethical method used to mark crested porcupine quills, which involves the use of colored adhesive tapes applied to quills. The retention period of this marking technique lasts up to 9 months, allowing short-term field studies and possibly dispersal distances measurements. The method could be improved by doubling the number of marked spines and by reapplying adhesive tape at every recapture event. Moreover, the use of a marking code can be obtained by subdividing the body of the hedgehog into six body areas, to increase the number of marking possibilities, through the combination of tape colors and body areas.     

One step forward: contrasting the effects of Toe clipping and PIT tagging on frog survival and recapture probability

Amphibians have been declining worldwide and the comprehension of the threats that they face could be improved by using mark–recapture models to estimate vital rates of natural populations. Recently, the consequences of marking amphibians have been under discussion and the effects of toe clipping on survival are debatable, although it is still the most common technique for individually identifying amphibians. The passive integrated transponder (PIT tag) is an alternative technique, but comparisons among marking techniques in free‐ranging populations are still lacking. We compared these two marking techniques using mark–recapture models to estimate apparent survival and recapture probability of a neotropical population of the blacksmith tree frog, Hypsiboas faber. We tested the effects of marking technique and number of toe pads removed while controlling for sex. Survival was similar among groups, although slightly decreased from individuals with one toe pad removed, to individuals with two and three toe pads removed, and finally to PIT‐tagged individuals. No sex differences were detected. Recapture probability slightly increased with the number of toe pads removed and was the lowest for PIT‐tagged individuals. Sex was an important predictor for recapture probability, with males being nearly five times more likely to be recaptured. Potential negative effects of both techniques may include reduced locomotion and high stress levels. We recommend the use of covariates in models to better understand the effects of marking techniques on frogs. Accounting for the effect of the technique on the results should be considered, because most techniques may reduce survival. Based on our results, but also on logistical and cost issues associated with PIT tagging, we suggest the use of toe clipping with anurans like the blacksmith tree frog.     

Marking hard-shelled gastropods: tag loss, impact on life-history traits, and perspectives in biology

Abstract. Individual marking has long been used in many fields of biology. However, capture–mark–recapture (CMR) studies are not evenly distributed among taxonomic groups, with most studies focusing on vertebrates. For example, a limited number of studies have been conducted in gastropods, in sharp contrast to their important role as biological models or exploited natural resources. The lack of standard, validated marking techniques certainly contributes to the limited use of CMR. In this article, we evaluate two fundamental requirements for a marking technique to be suitable, i.e., tag loss (two experiments) and impact on life-history traits (survival, growth, and fecundity, in three experiments). Five marking techniques for hard-shelled gastropods were tested in the freshwater snail Physa acuta (Pulmonata). The tag-loss rate per month was lower for glued plastic marks (0.01) than for paint marks (0.03–0.07), and the tag-loss rate varied among colors (gouache paint). Under laboratory conditions, the life-history traits were not significantly affected by marking. We thus recommend using glued plastic marks for long-term studies, and paint marks for mass marking, with double marking to account for tag-loss rate. Based on an extensive literature survey, we also review current CMR practices in gastropod studies and suggest general improvements that would prove useful in both this group and invertebrates in general.     

Stopover duration of Palearctic passerine migrants in the western Sahara – independent of fat stores?

Birds on migration spend much more time on stopover sites to refuel for the next migration step than aloft, but empirical data on stopover duration are rare, especially for Palearctic trans-Sahara migrants whilst crossing the desert. Previous studies suggest that stopover duration of fat birds in oases is much shorter than that of lean birds. During 2003 and 2004 capture–recapture data of migrating passerines from two inland oases in spring and from one coastal site in autumn in Mauritania, West Africa, were analysed to test whether the probability of being a transient and the stopover duration depend on fuel stores at first capture. The application of capture–recapture models revealed that during autumn migration at the coast the proportion of transients (individuals that stop over only for 1 day) was relatively high (77–90%) in three out of four species investigated and stopover duration was short (1.9–4.6 days). In the inland oases in spring, transients were detected in only four out of 12 analyses. Stopover duration was longer than at the coast in autumn and surprisingly long in some species with durations of up to 30 days. Models taking into account the initial fat load of birds on the first capture occasion were, with one exception, never the most parsimonious ones. This indicates that the time spent after and before capture at the stopover site did not depend on the fat stores at first capture. Therefore, we cannot confirm the assumption that birds arriving at stopover sites in the desert with low fat loads stay longer than birds that arrive with high fat loads.     

Mark retention and fish survival associated with a low-cost marking technique for common carp Cyprinus carpio (Linnaeus, 1758)

Common carp (Cyprinus carpio, [Linnaeus, 1758]) have long been established in the United States and in some cases their populations can be very dense, leading biologists to expend significant effort towards reducing numbers of common carp in some populations. Estimating abundance of common carp prior to removal efforts would be useful in evaluating success of these removal efforts, but marking large numbers of fish can be expensive. Therefore, a low-cost tagging option is needed. In this study, we used tank and field experiments to determine the retention and longevity of hole-punch marks in the opercula of common carp. For the tank experiment, fish were double marked with a size-3 self-piercing tag and an operculum hole-punch mark (using a paper hole-punch tool with a hole diameter of 6.4 mm) on opposite sides of the fish. Over the entirety of the 180–day tank experiment, retention of the self-piercing tags and hole-punch marks was 100% and no marking mortality was observed. For the field experiment, 883 common carp were tagged at random in two groups, a double-marked group (n = 416, both self-piercing tags and hole-punch) and a single-mark group (n = 467, self-piercing tag). Fish were sampled monthly for 398 days. Because the length distribution sampled was bimodal, we evaluated tag retention of fish <330 mm TL (small fish, n = 273) and > 331 mm TL (large fish, n = 143), separately. Hole-punch mark retention was high for both size classes throughout most of the field experiment. For large fish, retention of hole-punch marks was 100% for the entire 398-day experiment. For small fish, retention of hole-punch marks was 100% through 184-day and remained above 93% through 328-days, but declined to 0% by day 398. Our results suggest that the operculum hole-punch mark is a valuable low-cost, long-term technique for tagging common carp.     

Effect of light‐level geolocators on apparent survival of two highly aerial swift species

Light‐level geolocators are currently widely used to track the migration of small‐sized birds, but their potentially detrimental effects on survival of highly aerial species have been poorly investigated so far. We recorded capture–recapture histories of 283 common swifts Apus apus and 107 pallid swifts Apus pallidus breeding in 14 colonies in Italy, Spain, Sweden and Switzerland that were equipped with 10 different types of geolocators (‘geolocator birds’), and compared their survival with that of, respectively, 215 common and 101 pallid swifts not equipped with geolocators (‘control birds’). Data were analysed using both GLMMs with return rate as a proxy for survival and mark–recapture models to estimate survival while accounting for recapture probability. In all the analyses, geolocator birds showed reduced apparent survival compared to controls. Geolocator weight was always lower than 3% of body mass, and did not affect survival per se. Geolocators with a light‐stalk, which is used in some geolocator models to reduce light sensor shading by feathers, decreased apparent survival more than models without light‐stalk. Apparent survival of geolocator birds significantly varied among sites, being much higher in northern Europe. Despite in our analyses we could only partly account for variable recapture probabilities among sites and for inter‐annual variability in survival, our results generally showed that equipping swifts with geolocators decreased their survival prospects, but also that the magnitude of this effect may depend on species‐specific traits. These conclusions are in line with those of other studies on aerial foragers. We suggest that future studies tracking the movements of aerial insectivorous birds should use devices designed to minimize drag.     

Marking Triatoma brasiliensis,Triatoma pseudomaculata and Rhodnius nasutus Nymphs with Trace Elements: Element Persistence and Effects of Marking on Insect Mortality

BackgroundField ecologists often rely on mark-release-recapture (MRR) experiments to estimate population dynamics parameters for a given species. In the case of a medically important taxon, i.e., a disease vector, inferences on species survival and dispersal rates are particularly important as they have the potential to provide insights into disease transmission dynamics in endemic areas. Medical entomologists have traditionally used fluorescent dusts to externally mark the cuticle of insects. However, dust marking is usually restricted to the adult life stage because immature insects lose the mark when they molt.Conclusions/SignificancePrevious evidence shows that there is little or no genetic differentiation between populations at the microgeographic level, which often precludes indirect estimations of dispersal capability based on genetic markers. In such situations, MRR studies are more suitable as they measure insect movement directly from one site to another, instead of effective migration (i.e. gene flow). The determination of a reliable and persistent marking method is the first step towards the development of meaningful ecological estimates through the application of MRR methodology. Here, we have identified trace elements that can be used for mark and recapture studies of three triatomine species in Brazil.     

Sex-biased survival and breeding dispersal probability in a patchy population of the Rock Sparrow Petronia petronia

Demographic parameters of the polygynous Rock Sparrow Petronia petronia were investigated in a small patchy population in the Italian Alps. The population included two distinct breeding patches that differed in altitude and breeding success. Survival parameters were estimated by capture–recapture analysis of 170 individually marked animals. At the whole population level (Cormack–Jolly Seber model), no sex difference in local survival probability was detected. We then used a multisite capture–recapture approach (Arnason–Schwarz model) to investigate patch-specific survival probability and between-patch dispersal rate conditional on survival. Female local survival in the higher-altitude patch (mean ± se: 0.54 ± 0.04) was significantly greater than in the other patch (0.37 ± 0.04), probably because permanent emigration from the study area was greater. In the higher-altitude patch, breeding dispersal was constrained by the altitude limit and breeding movements were directed toward the patch at lower altitude. The probability of changing patch in the next breeding season was significantly higher for females (range 0.16–0.21) than for males (0.01–0.03). Breeding success varied between years and patches, being lower in the patch where frequency of polygamy and female local mortality were higher.     

Resident and transient dynamics, site fidelity and survival in wintering Blackcaps Sylvia atricapilla: evidence from capture–recapture analyses

In their winter quarters, migrant birds may either remain within a small area (resident strategy) or move frequently over a large area looking for locally abundant food (transient strategy). It has been suggested that both strategies could simultaneously occur in the same population. We used time-since-marking capture–recapture models to infer the coexistence of these two behavioural strategies (transient and resident) among wintering Blackcaps Sylvia atricapilla using weekly recapture data over a 7-year period. A related question is whether Blackcaps, if surviving to the next winter, always return to the same wintering area, so we also used this approach to analyse winter site fidelity and to estimate annual survival probabilities. Model selection supported the existence of heterogeneity in survival estimates for both the within-season and the interannual survival probabilities, i.e. there was evidence for the existence of transients. It was estimated that 26% of the Blackcaps were resident during the winter. Mean apparent annual survival probability was 0.46 (se = ±0.11). However, there was some evidence suggesting that not all individuals showed winter site fidelity. The estimated proportion of individuals that, if alive, returned to the wintering area was 28%. This is the first study to show the existence of these two behavioural strategies (residence and transience) among wintering Blackcaps, and the first confirming this pattern using capture–recapture models. These models considering transient and resident dynamics may become an important tool with which to analyse wintering strategies.     

Estimates of Apparent Survival Rates for Forest Birds in Eastern Ecuador

Knowledge of survival rates of Neotropical landbirds remains limited, with estimates of apparent survival available from relatively few sites and species. We used capture–mark–recapture models to estimate apparent survival of 31 species from eastern Ecuador based on data collected from 2001 to 2006. Models assuming constant survival had highest support for 27 species; models incorporating effects of transients were highest for four. Average apparent survival across 30 species of passerines was 0.58 (± 0.02 SE); apparent survival was lower during the first interval after initial capture (φ₁: mean = 0.49 ± 0.03) than during subsequent intervals (φ₂: mean = 0.60 ± 0.02). Apparent survival was similar among three families represented by at least four species (Thamnophilidae: 0.57 ± 0.03, N = 10; Furnariidae: 0.59 ± 0.03, N = 5; Pipridae: 0.56 ± 0.02, N = 4). There was no indication that species that occur in flocks had higher survival than nonflocking species (obligate flock members: 0.57 ± 0.03, N = 10; facultative flock members: 0.56 ± 0.04, N = 5; nonflocking: 0.59 ± 0.03, N = 15). Comparisons of published estimates of apparent survival of tropical species demonstrated substantial differences among species and, in some cases, within species across different sites in the Neotropics. Our results support previous studies that concluded that early estimates of high (> 85%) survival in tropical birds may not be representative of all tropical species. Future studies should focus on understanding factors ( e.g. , life-history traits) that promote differences in survival among species within tropical forests.