Effects Of Radiotransmitters Research Articles

Radio-tracking systems emit pulsed waves that could affect the health and alter the orientation of animals

Any study carried out with a given technique must avoid causing harmful effects on the experimental subjects, in order to avoid altering the survival rates of the animals or causing bias in the results of the study. Radio tagging is undoubtedly a very useful technique, and in many cases is the only option available to obtain information on the ecology and movements of wild animals, but unfortunately it has been used indiscriminately, without regard to the problems it can cause. The most well-known of these are the effects from the weight of the device and the harness, but there are others that have not yet been taken into account and that have not been sufficiently studied, such as the non-thermal effects of modulated and/or pulsed electromagnetic fields on the health and orientation of radio-tracked animals. This commentary provides a brief overview of the scientific evidence on the effects of electromagnetic fields, and underlines the importance of carrying out relevant studies in order to check for the possible effects of radio transmitters on animals.

Effects of radiotransmitters and breeding effort on harvest and survival rates of female mallards

AbstractThere has been widespread speculation that breeding activity places adult female mallards (Anas platyrhynchos) at heightened risk of harvest due to insufficient time to complete the wing molt or recover body condition prior to onset of hunting and autumn migration. We tested the hypotheses that breeding females have higher rates of harvest and reduced prospects for survival by estimating band recovery rates (f) and annual survival (S) in relation to individual measures of breeding effort for 3,055 adult female mallards that had been banded and radiomarked during the breeding season in the Prairie‐Parkland Region of Canada, 1993–2000. Birds that had been marked with external prong‐and‐suture transmitters had lower estimated survival rates (S = 0.518, SE = 0.118) than birds marked with implant transmitters (S = 0.731, SE = 0.061), but rates for birds marked with implant transmitters did not differ from expectations based on other studies for females marked only with legbands. After excluding external transmitters, we found that recovery rates were unaffected by any measures of reproductive effort, but annual survival was lower for females that tended broods to 60 days of age (S = 0.474 ± 0.115) versus females that never hatched a nest (S = 0.654 ± 0.042). Telemetry data indicated that brood‐rearing females experienced extremely low mortality, so reduced survival of females that raised broods presumably resulted from insufficient time to molt and prepare for autumn migration. Management efforts that promote successful early nesting attempts may also improve adult female survival by allowing females more time to molt and prepare for autumn migration, whereas hunting regulations designed to protect late‐breeding females may prove ineffective if such individuals have higher natural mortality. © 2012 The Wildlife Society.

Effects of radiotransmitters and plasticine bands on Mallard duckling survival

Individual markers are essential for measuring survival rates, but few reliable techniques exist for marking young waterfowl. We banded 572-d-old Mallard (Anas platyrhynchos) ducklings from 85 broods with plasticine-filled leg bands in 2006–2007 and marked 82 hatchling Mallards from 43 broods with 1.8-g back-mounted prong-and-suture transmitters in 2006. We compared survival probabilities of marked ducklings and 621 unmarked ducklings from 110 broods where only the female was radio-marked using the nest survival module in Program MARK. The best-supported model recognized deleterious effects of both radiotransmitters (β=−0.82, 85% CI =−1.32 to −0.33) and plasticine bands (β=−0.29, 85% CI =−0.55 to −0.03). Cumulative survival to 30 d of age for unmarked ducklings averaged 0.22 (process variation; σ= 0.11) in 2006 and 0.20 (σ= 0.11) in 2007, whereas 30-d survival of banded ducklings during these 2 yr was 0.14 (σ= 0.09) and 0.13 (σ= 0.09), respectively. Radio-marked ducklings averaged 0.04 (σ= 0.03) cumulative survival in 2006. Although capturing ducklings after they leave nests is not always possible, post hoc analysis showed that marker effects decreased with duckling age and waiting until ducklings were at least 4 d old before marking would have negated these effects. Because marking hatchling Mallards with either radiotransmitters or plasticine bands negatively impacted their survival, we do not recommend these marking techniques for newly hatched ducklings. RESUMEN Marcas individuales son esenciales para medir tasa de supervivencia, pero existen pocas tecnicas confiables para marcar aves acuaticas. Anillamos 572 polluelos de un dia de nacidos de Anas platyrhynchos pertenecientes a 85 nidadas con anillos rellenos de plastilina en el 2006 y en el 2007, adicionalmente marcamos 82 polluelos recien eclosionados de 43 nidadas con transmisores colocados en la espalda de 1.8 g en el 2006. Comparamos probabilidades de supervivencia de juveniles marcados y de 621 no marcados correspondientes a 110 nidadas en las cuales solo las hembras fueron marcadas con radios, usando el modulo de probabilidad de supervivencia de nidos en el programa MARK. El modelo que obtuvo el mayor soporte se encontro que los radio transmisores tuvieron efectos deletereos (β=−0.82, 85% CI =−1.32 to −0.33), al igual que los anillos de plastilina (β=−0.29, 85% CI =−0.55 to −0.03). La supervivencia acumulada a los 30 dias de edad para los juveniles no marcados tuvo un promedio de 0.22 (variacion de proceso; σ= 0.11) en el 2006 y 0.20 (σ= 0.11) en el 2007, mientras que la supervivencia acumulada a los 30 dias de edad para los juveniles marcados durante estos dos anos fue 0.14 (σ= 0.09) y 0.13 (σ= 0.09), respectivamente. Los juveniles marcados con radios promediaron 0.04 (σ= 0.03) de supervivencia acumulada en el 2006. A pesar de que la captura de los polluelos despues de que dejan el nido no siempre fue posible, post-test analisis mostraron que los efectos del marcaje disminuyeron con la edad de los juveniles y esperar hasta que los polluelos lleguen a la edad de 4 dias antes de ser marcados habria anulado estos efectos negativos. Debido a que el marcaje de los polluelos de A. platyrhynchos tanto con radio transmisores o anillos de plastilina tuvieron un impacto negativo en su supervivencia, no recomendamos estas tecnicas de marcaje para polluelos recien eclosionados en patos.

Technique, Safety, and Efficacy of Intra‐Abdominal Transmitters in Nine‐Banded Armadillos

ABSTRACT The future management of nine‐banded armadillos (Dasypus novemcinctus) requires solid space‐use and activity data, which are currently lacking and which radiotelemetry can provide. External radiotransmitters have not been successful applied with this species. To make recommendations for intra‐abdominal radiotransmitter placement in nine‐banded armadillos, we 1) evaluated 4 different anesthetic protocols for safety, efficiency, and cost‐effectiveness; 2) evaluated a surgical technique for the intra‐abdominal placement of radiotransmitters that addresses problems described in previous studies; and 3) evaluated the physiologic and behavioral effects of such a technique. We captured and surgically implanted 37 nine‐banded armadillos using either butorphanol and isoflurane, ketamine alone, ketamine and xylazine, or a combination of butorphanol, ketamine, and medetomidine for anesthesia. We recovered and necropsied armadillos after the completion of the study. The objective and subjective assessment of butorphanol, ketamine, and medetomidine combination protocol, followed by reversal of the anesthesia with atipamezole, showed that it was the best overall anesthetic protocol for field use, providing both a smooth induction and fast recovery. We evaluated the fate and effects of radiotransmitters on 13 recovered animals at the end of the study and found no adverse effects. We recommend the implantation of radiotransmitters that are allowed to free‐float within the abdominal cavity and specifically emphasize the need for strict aseptic technique. Wildlife managers and wildlife veterinarians aiming to implant nine‐banded armadillos with radiotransmitters will benefit from using the recommended anesthetic protocol and surgical technique in future studies.

Effects of radio transmitters on the behavior of Red-headed Woodpeckers

ABSTRACT Previous studies have revealed that radio-transmitters may affect bird behaviors, including feeding rates, foraging behavior, vigilance, and preening behavior. In addition, depending on the method of attachment, transmitters can potentially affect the ability of cavity-nesting birds to use cavities. Our objective was to evaluate effects of transmitters on the behavior of and use of cavities by Red-headed Woodpeckers (Melanerpes erythrocephalus). Using backpack harnesses, we attached 2.1-g transmitter packages that averaged 3.1% of body weight (range = 2.5–3.6%) to Red-headed Woodpeckers. We observed both radio-tagged (N= 23) and nonradio-tagged (N= 28) woodpeckers and determined the percentage of time spent engaged in each of five behaviors: flight, foraging, perching, preening, and territorial behavior. We found no difference between the two groups in the percentage of time engaged in each behavior. In addition, we found that transmitters had no apparent effect on use of cavities for roosting by radio-tagged woodpeckers (N= 25). We conclude that backpack transmitters weighing less than 3.6% of body weight had no impact on either their behavior or their ability to use cavities. Estudios anteriores han revelado que radio transmisores pueden afectar el comportamiento de las aves, incluyendo tazas de alimentación, comportamientos de búsqueda de alimento, vigilancia, y acicalamiento. Adicionalmente, dependiendo del método de colocación, los transmisores pueden potencialmente afectar la habilidad del uso de las cavidades por parte de las aves que anidan en cavidades. Nuestro objetivo fue evaluar los efectos de los transmisores en el comportamientos y uso de las cavidades por Melanerpes erythrocephalus. Usando arneses en forma de mochila, pegamos radio transmisores de 2.1-g que promediaron 3.1% del tamaño corporal (rango = 2.5–3.6%) de Melanerpes erythrocephalus. Observamos carpinteros con radio transmisores (N= 23) y sin radio transmisores (N= 28) y determinamos el porcentaje del tiempo que pasaron en cada uno de los cinco comportamientos: vuelo, buscando alimento, perchado, acicalándose, y comportamiento territorial. No encontramos diferencias entre dos grupos en el porcentaje de tiempo que pasaron realizando cada comportamiento. Adicionalmente, encontramos que los transmisores no tienen un efecto aparente en el uso de cavidades para dormir por parte de los carpinteros que tenían radio transmisores (N= 25). Concluimos que los transmisores tipo mochila que pesan menos de 3.6% del peso corporal del ave no tienen impacto en el comportamiento o en la habilidad de usar cavidades por parte de Melanerpes erythrocephalus.

Effect of radio transmitters on return rates of Swainson's Warblers

Although radio telemetry can provide useful information, the possible negative effects of transmitters, including biased results and detrimental effects on the birds, must also be considered. Several investigators have examined the effects of transmitters on larger birds, but few have examined their possible long-term effects, as assessed by return rates, on small passerines. We examined the possible negative effects of transmitters on a small (15.5 g) passerine. We used glue to attach radio transmitters to 40 male Swainson's Warblers (Limnothlypis swainsonii) at two study sites in Arkansas in 2005 and 2006. To assess possible effects of transmitters on survival, we compared the following-year return rates of radio-tagged birds to birds that were captured and color banded, but did not receive transmitters. Least squared mean return rates for all birds ranged between 0.46 and 0.57. We found no significant difference in the following-year return rate of radio-tagged and nonradio-tagged birds. In addition, we found no significant differences in return rates between study sites or years, and no significant interactions between any combination of radio transmitter (radio tagged or not), site, and year. Our results indicate that attachment of transmitters did not affect return rates of male Swainson's Warblers and that the glue-on technique is a good option for short-term studies of small passerines. RESUMEN. Efecto de radiotransmisores en las tasas de retorno de individuos de Limnoth- lypis swainsonii Aunque la radiotelemetr´ oa puede proveer de informaci´ on de utilidad, el posible efecto negativo de estos, incluyendo sesgo en la informaciy efecto detrimental, tambidebe tomarse en consideraci´

Off-territory movement of male American Redstarts (Setophaga ruticilla) in a fragmented agricultural landscape is related to song rate, mating status and access to females

Male songbirds often move off-territory to pursue extra-pair fertilizations. This movement represents a trade-off between paternity gain and loss and can be influenced by male quality and access to fertile females. Access to females could be reduced in fragmented landscapes that have small patches and low connectedness. We studied movement and extra-pair fertilization success of radio-tracked male American Redstarts (Setophaga ruticilla) in forest patches in an agricultural landscape in Alberta, Canada, over 2 years. Males spent an average of 18% of their time off-territory, mostly intruding onto adjacent territories and rarely moving between patches. They averaged 0.8 trips/h, with mean trip duration of 17 min and mean trip distance of 104 m. Less time was spent off-territory when their mate was nest-building and males intruded most often onto territories with nest-building females. Males with higher song rates and more nearby females intruded most onto other territories. Monogamous males in better condition with higher song rates spent the most time off-territory. However, males with more nearby females and higher local breeding synchrony spent the least time off-territory, suggesting these males face a trade-off between seeking extra-pair fertilizations and protecting against cuckoldry. Forest cover was not an important predictor of movement. Investment in off-territory movement did not predict extra-pair fertilization success or probability of cuckoldry. However, few tracked males achieved extra-pair fertilizations (1/22 tracked males vs 18/57 non-tracked males), possibly an artefact of low sample size or the effect of radio transmitters on female choice.

Do radio collars influence mortality and reproduction? A case with ring-necked pheasants (Phasianus colchicus) in Central Italy

The effect of radio transmitters on bird survival and reproduction has been explored in the literature, and contradictory results were found. Using the Kaplan-Meier method, we estimated the mortality of female ring-necked pheasants (Phasianus colchicus) in relation to radio load (percentage of total body mass). Low-load birds showed a higher survival, particularly after 2-3 months from release, thus excluding short-term effects of handling and adjusting to packages. Reproductive success was higher for birds with low loads, but the effect was less clear. The results were not influenced by age or body mass. As a rule of thumb, using radio packages lighter than 1.5% of the body mass can be considered safe for pheasants, whereas loads above 2% may have adverse effects.

Hematological stress indices reveal no effect of radio-transmitters on wintering Hermit Thrushes

Radio-telemetry is often used to track birds, and several investigators have examined the possible effects of radio-transmitters on birds. One approach to this question is to determine if transmitters induce physiological stress. Using hematological indicators of stress (heterophil-lymphocyte (H/L) ratios), studies of captive birds have revealed no evidence that radio-transmitters cause stress. However, studies in captivity may not reflect conditions faced by birds in the wild, especially during energetically demanding times, such as the overwintering period. We examined the possible effect of backpack-style transmitters on overwintering Hermit Thrushes (Catharus guttatus) in South Carolina by examining H/L ratios from blood smears made before and after transmitter attachment. We captured and recaptured eight thrushes in an early winter period and 11 in a late winter period, and in both cases found that H/L ratios did not change after 1 mo of carrying transmitters. H/L ratios also did not differ significantly (in either trial) between thrushes with and without transmitters. Furthermore, thrushes that carried transmitters during both of our trials did not have higher final H/L ratios than those that carried transmitters during just one trial (the late winter). These results indicate that carrying backpack-style transmitters for 1 mo did not induce stress in overwintering Hermit Thrushes. These results are consistent with studies of captive birds, and provide support for the continued use of backpack radio-transmitters in this species, as long as weight recommendations are met. SINOPSIS. Losde estr´ es hematol´ ogico revelan ning´

Effect of Radiotransmitters on Northern Bobwhite Annual Survival

Abstract: Radiotelemetry has been widely used in northern bobwhite (Colinus virginianus) research to estimate survival rates and other demographic parameters. Biologists have used this knowledge to study bobwhite ecology, develop management theory, and base management actions. We tested the assumption that radiotransmitters do not bias survival rates of bobwhites by comparing survival rates of banded bobwhites with and without radiotransmitters on Tall Timbers Research Station (TTRS) from 1999 to 2004. We used Burnham's model in Program MARK and model‐selection procedures to determine relative importance of year, gender, and radiotagged status on annual survival rates and recovery processes. Three plausible models (relative quasi‐likelihood Akaike's Information Criterion [ΔQAICc] < 3) included year dependence in survival and an additive effect of gender but no radiotransmitter effect. Models including a radiotransmitter effect in survival were >8 ΔQAICc from the top models, had low Akaike model weights (wi < 0.007), and low importance weight (S̀wi(radio) = 0.01). We also compared band—recapture survival estimates from the QAICc minimizing model to staggered entry Kaplan—Meier (KM) survival estimates from 2000 to 2003. Annual KM survival estimates of male and female bobwhites were within the 95% confidence interval of band—recapture estimates in 7 of 8 comparisons. We conclude that radiotelemetry is a reliable technique for determining bobwhite survival. Managers should view information from properly conducted telemetry research as reliable and useful for management.

Effective subcutaneous radiotransmitter implantation into the furcular cavity of chukars

The wide use of radiotelemetry in avian field studies justifies the continued search for improved methods of attaching transmitters. Subcutaneous implantation of radiotransmitters into the furcular cavity of birds has been proposed to ameliorate many deleterious effects of radiotransmitters (J. Berdeen, South Carolina Cooperative Research Center, personal communication). Using wild adult chukars (Alectoris chukar) brought into captivity, we implanted radiotransmitters subcutaneously into their furcular cavity and compared a suite of behavioral, endocrinological, and physiological measures in implanted chukars with controls. Implanted chukars did not differ from controls in maintenance, agonistic, or reproductive behaviors during 11 weeks of observation. Implanted chukars also did not differ from control chukars in an array of blood values designed to test for infection or implant rejection and did not experience chronic stress based on circulating corticosterone levels. Necropsy indicated complete healing of insertion sites with no signs of infection, foreign body reaction, or rejection. Implanted chukars did not differ from controls in mass, body fat, fecundity, or reproductive condition. We conclude that subcutaneous implantation of radiotransmitters into the furcular cavity was well tolerated by chukars and may prevent deleterious effects associated with other methods of transmitter placement.

Effects of radiotransmitters on the reproductive performance of Cassin’s auklets

We examined whether radiotransmitters adversely affected the reproductive performance of Cassin's auklets (Ptychoramphus aleuticus) breeding on the California Channel Islands during 1999-2001. We attached external radiotransmitters to 1 partner in 108 Cassin's auklet pairs after nest initiation and used 131 unmarked, but handled, pairs as controls. Compared to alpha chicks raised by radiomarked pairs, alpha chicks raised by unmarked pairs had faster mass growth rates (1.95 ± 0.30 g d−1 vs. 3.37 ± 0.53 g d−1, respectively), faster wing growth rates (2.46 ± 0.10 mm d−1 vs. 2.85 ± 0.05 mm d−1), greater peak fledging masses (118.9 ± 3.5 g vs. 148.3 ± 2.4 g), and higher fledging success (61% vs. 90%). Fledging success was reduced more when we radiomarked the male (50% fledged) rather than the female partner (77% fledged). After fledging an alpha chick, unmarked pairs were more likely to initiate a second clutch (radiomarked: 7%; unmarked: 39%) but did not hatch a second egg (radiomarked: 4%; unmarked: 25%) or fledge a second (beta) chick (radiomarked: 4%; unmarked: 18%) significantly more often than radiomarked pairs. We resighted 12 radiomarked individuals nesting during a subsequent breeding season; each bird had shed its transmitter and healed the site of attachment. We suggest caution in using telemetry to evaluate the reproductive performance of alcids, but marking only females may minimize adverse effects.

Effects of Radiotransmitters on Survival and Reproductive Success of Gray Partridge

Because of the recent decline in gray partridge (Perdix perdix) populations in northern France, we conducted a field study in 1995-97 by using radiotelemetry to examine mortality causes. We investigated the effects of radiotransmitters on survival, reproductive success, and body mass of gray partridge. We captured 260 hens in spring 1995, 99 in autumn 1995, and 358 in spring 1996 and tagged them with a 10-g necklace radiotransmitter. We found no effects of radiotags on survival (P = 0.101), reproductive success (P = 0.375), and body mass (P = 0.990) in spring 1995. In contrast, adverse effects were observed in spring 1996 on survival (P < 0.001), reproductive success (P = 0.006), and body mass (P = 0.013). The postrelease effect on survival observed in spring 1996 varied among populations (P < 0.001), between radio types (P = 0.036), and with regard to body mass at time of capture (P = 0.046). The differences observed between years and across study areas were correlated to weather and predator abundance but not to habitat features we measured. Our findings suggest that radiotelemetry data must be carefully interpreted with regard to potential radiotag effects, all the more that these effects are influenced by environmental conditions.

Effects of Nest and Brood Visits and Radio Transmitters on Rock Ptarmigan

The effect of researchers on animal behavior and survival has received attention, and avian studies have reported results ranging from few effects to decreases in reproductive success and survival. We examined potential effects of researchers'nest and brood visits on rock ptarmigan (Lagopus mutus) survival and breeding success and the effects of radio transmitters on ptarmigan survival in the central Canadian Arctic in 1988-89. Predation rate of hens (P = 0.92), clutch size (P = 0.28), number of chicks leaving the nest (P = 0.93), and nesting success (P = 0.86) did not differ between disturbed (flushed hen off nest) and undisturbed (determined hen's status on or off nest by telemetric triangulation) nests. Brood size at fledge (P = 0.89) and fledging success (P = 0.14) did not differ between broods that were visited frequently (every 3-4 days) or infrequently (every 6-9 days). Approximately half (n = 27) of the males captured and banded were fitted with radio transmitters. Survival of radio-marked males (S = 0.62) was lower than that of unmarked males (S = 1.00) in 1988 (P = 0.03) and for years pooled (radiomarked, S = 0.55; unmarked, S = 0.83; P = 0.008), but not in 1989 (P = 0.11). Transmitters weighed more in 1988 than 1989 (3.6 vs. 2.3% body mass, respectively). Studies should consider potential effects of researchers and test for them to detect biases that may exist and to develop methods and equipment that have minimal effect on the study animal

Effects of Radio Transmitters on Nesting Captive Mallards

Radio packages may subtly affect bird behavior and condition, and thus could bias results from studies using this technique. To asses effects on reproduction of mallards (Anas platyrhynchos), we tested 3 types of back-mounted radio packages on captive females. Eight paired females were randomly assigned to each of 4 treatments: 4-g transmitter attached with sutures and glue, 10-g or 18-g transmitter attached with a harness, and no transmitter (control). All mallards were fed ad libitum. No differences were detected among treatments in number of clutches, clutch size, nesting interval, egg mass, or body mass; powers (range = 0.15-0,48) of tests were low. Feather wear and skin irritation around radio packages were minimal

Effects of Radiotransmitters and Fluorescent Powders on Activity of Wild House Mice (Mus musculus)

The effects of radiotransmitters and fluorescent powders on the exercise-wheel-running activity of wild house mice ( Mus musculus ) were measured. Numbers of wheel revolutions run by 160 house mice at 6, 24, and 96 h, were recorded after they were exposed to one of five treatments (control, collar-control, powder-control, radiocollar, and powder). Control groups exhibited equal activity at the three time intervals. Radiocollared mice and those covered with fluorescent powders exhibited reduced activity at 6 h; radiocollared mice exhibited a reduction in activity that persisted at least 96 h.

The Effect of Radio Transmitters on the Behavior of Common Murres and Razorbills during Chick Rearing

We compared site attendance, length and number of absences from the colony, and prey delivered to the young of control Common Murres (Uria aalge) and others which carried radio transmitters that had either an external or internal aerial during chick rearing. Birds with the internal aerial behaved similarly to control birds. However, birds with the external aerial spent less time in the colony, were absent for long continuous periods, and often returned without a fish for the chick. This did not reduce fledging success because their mates compensated by increasing the food brought in. Fewer observations were made on Razorbills (Alca torda) with external aerial transmitters, but they indicated no profound effect on behavior.

Effects of Radio Transmitters on Released Cock Pheasants

Effects of Radio Transmitters on Released Cock Pheasants