[ENG]The behavior,b reeding successa nd survivalo f radio-taggeda nd non-radio-tagged
(control) Lesser Kestrels (Falco naumanni) in southern Spain in 1989-1990 were compared.
The copulation period, copulation rates and prey delivery rates to both mates and nestlings
did not differ significantlyb etween radio-taggeda nd control individuals.I n addition, there were no differences in annual survival  rates or breeding success between radio-tagged and control birds.[ESP]-Sec ompararon aspectosd e comportamiento,6 xito reproductor y supervivencia
entre cernlcalosp rimillas (Falco naumanni) portadores de radiotransmisorese n la cola y
otros marcados finicamente con anillas (controles) en el sur de Espafia en 1989-1990. E1
periodo de c6pulas, la frecuencia de las mismas, asi como las tasas de cebas de pareja y a
los pollos no se diferenci6 significativamentee ntre los individuosp ortadoresd e radiotransmisoresy
los controles.T ampoco se detectaron diferenciase n las tasasd e supervivenciaa nual
y 6xito reproductivo entre los dos grupos comparados.Peer reviewe

Donázar, José A.

Hiraldo, F.

Negro, Juan J.

Hiraldo, Fernando

Digital.CSIC

J. Field Ornithol., 65 (4) :466-471 EFFECTS OF TAIL-MOUNTED RADIO-TAGS ON ADULT LESSER KESTRELS FERNANDO HIRALDO, Josl• A. DONAZAR AND JuAN J. NEGRO • Estaci6n Biol6gica de Do•ana CSIC, Apdo. 1056 41080 Sevilla, Spain Abstract.--The behavior, breeding success and survival of radio-tagged and non-radio-tagged (control) Lesser Kestrels (Falco naumanni) in southern Spain in 1989-1990 were compared. The copulation period, copulation rates and prey delivery rates to both mates and nestlings did not differ significantly between radio-tagged and control individuals. In addition, there were no differences in annual survival rates or breeding success between radio-tagged and control birds. EFECTOS DE RADIO-EMISORES DE COLA EN CERNICALOS PRIMILLAS ADULTOS Sinopsis.--Se compararon aspectos de comportamiento, 6xito reproductor y supervivencia entre cernlcalos primillas (Falco naumanni) portadores de radiotransmisores en la cola y otros marcados finicamente con anillas (controles) en el sur de Espafia en 1989-1990. E1 periodo de c6pulas, la frecuencia de las mismas, asi como las tasas de cebas de pareja y a los pollos no se diferenci6 significativamente ntre los individuos portadores de radiotrans- misores y los controles. Tampoco se detectaron diferencias en las tasas de supervivencia anual y 6xito reproductivo entre los dos grupos comparados. Radio-telemetry is commonly used to monitor movements, habitat use and mortality of animals. The effects of radio-tags need to be examined, however, to determine if the data derived from their use are unbiased, and to ensure the well-being of the organisms under investigation. In some birds radio-tags appear to cause abnormal behavior, decreased pro- ductivity or reduced survival rates (e.g., Hines and Zwickel 1985, Johnson and Berner 1980, Marks and Marks 1987, Perry 1981, Sibly and McCleery 1980, Warner and Etter 1983). Few studies have evaluated the effects of radio-tags on birds of prey. Some have reported negative effects (Foster et al. 1992, Paton et al. 1991), whereas others reported no effects (Bray and Corner 1972, Kenward 1978, McCrary 1981, Sodhi et al. 1991). Beske (1978), Foster et al. (1992) and Paton et al. (1991) suggested that the negative effects could be related to how the transmitters were fixed to the animals (e.g., backpack-mounted vs. tail-mounted). The Lesser Kestrel (Falco naumanni) is a small migratory falcon (120- 200 g, Donfizar et al. 1992) whose populations have decreased dramati- cally in the Western Palearctic since the 1960s (Cramp and Simmons 1980, Gonz•lez and Merino 1990). It is presently endangered in Europe (Biber 1990), and despite its relative former abundance, many aspects of its biology are still unknown. Only since the late 1980s have studies, in- cluding the use of radio-telemetry, been undertaken in Spain (Don•tzar et al. 1992; Negro et al. 1992, 1993a, b). • Current address: Avian Science and Conservation Centre, Macdonald Campus of McGill Uni- versity, 21,111 Lakeshore, Ste-Anne de Bellevue, Qugbec, H9X 3V9, Canada. 466 Vol. 65, No. 4 Radio-tags onLesser Kestrels [467 Our objectives were to test the null hypotheses that birds wearing tail- mounted radio-tags did not differ from those marked only with PVC bands in: (1) behavior, (2) breeding success and (3) survival. METHODS Between February and July in 1989 and 1990, 14 adult Lesser Kestrels were fitted with radio-tags (three males and three females in 1989, and five males and three females in 1990) at Mairena del Alcor (37ø22'N, 5ø45'W), Seville province, southern Spain. The kestrels nested in an old castle where we counted 42 pairs in 1989 and 40 pairs in 1990. One-third of the adults in 1989 and two-thirds in 1990 wore PVC bands to permit individual recognition from a distance. The purpose of this study was to monitor their movements during foraging bouts and to quantify home range sizes (Don/tzar et al. 1993). Additional data on social behavior were recorded. Detailed information on the study area and trapping tech- niques were provided in Negro (1991) and Negro et al. (1993a, b). The number of control individuals varied depending on the parameter being estimated, as behavioral observations were only recorded in a small portion of the colony and more data were available for productivity and survival estimates (see Negro et al. 1992). The radio-tags (Urmeneta S.A., Arguedas, Spain) were attached dorsally to one or two central tail feathers and weighed on average 4.25 g (3.5% and 3.0% of the male and female minimum body mass, respectively, see Don/tzar et al. 1992). One transmitter failed a few hours after the bird was released. The rest lasted 2-12 wk. Behavior at the colony.--Observations were made 2-3 d per week and lasted from dawn to dusk. The entire breeding season was monitored, from the arrival of the first migrants in February to the end of the fledg- ling period in July. We spent 475 h in 1989 and 567 h in 1990 observing kestrels. Radio-tagged individuals and control birds nested in the same walls of the castle. Detailed information on the routine of recording be- havior was provided in Don/tzar et al. (1992) and Negro et al. (1992). We considered pairs in which at least one member of the pair was tagged as "marked" for mate-switching and copulation rate analyses. To estimate rates of mate-switching, as well as colony and nest-switching for banded individuals, we pooled the data from the study colony and two adjacent colonies, as there were no significant differences between colo- nies for those variables (Negro 1991). We pooled data from 1989 and 1990 for copulation analyses, as there were no significant differences be- tween years (Donfizar et al. 1992, Negro et al. 1992). The copulation period was estimated as the time between the first and last observed cop- ulation for each pair. The total number of copulations per season was estimated by multiplying the mean number of copulations per day by the duration of the copulation period (the number of days of observation for each pair is given in Table 1). We considered males and females separately for prey delivery analyses because males usually fed the young more than females (unpubl. data). 468] F. Hiraldo et al. .l. Field Ornithol. Autumn 1994 TABLE 1. Breeding success and survival rates of radio-tagged and control Lesser Kestrels in Spain, 1989-1990. Radio-tagged Controls n • • SD n • • SD Copulation period (d) 4 Copulations/season 4 Mate-feeds/h 1989 1 2 1990 Chick-feeds/h Males 1989 2 Females 1989 3 Males 1990 1 Females 1990 2 % mate-switching 5 % nest-switching 7 % colony-switching 10 Clutch size 7 Fledged young 10 Survival 1989 6 1990 8 83.7 9.5 6 79.3 5.2 (32, 31, 29, 45) (33, 30, 19, 31, 32, 32) 235.2 32.7 6 361.5 47.4 0.48 4 0.42 0.06 (7) (3, 11, 12, 7) 0.44 0.16 3 0.49 0.04 (17, 16) (12, 10, 12) 1.69 3 1.33 0.38 (8, 5) (8, 6, 5) 0.89 0.22 2 0.95 0.13 (8, 5, 6) (5, 4) 0.83 3 1.02 0.46 (12) (11, 13, 12) 0.62 2 0.53 (11, 13) (11, 11) 100.0 61 70.5 100.0 40 75.0 10.0 130 7.7 4.6 0.5 29 4.2 0.90 1.5 1.3 71 1.7 1.00 66.7% 122 78.7% 75.0% 141 66.7% • Number of pairs (copulation period, copulations/season, clutch size and fledged young) or number of individuals (all other variables). Number of days that each pair or individual was observed are indicated in parentheses. We also considered each year separately for prey-delivery analyses because of variation among radio-tagged males (Kruskal-Wallis test, H = 12.57, 1 df, P< 0.01), radio-tagged females (H= 7.90, 1 df, P< 0.01) and control females (H= 7.90, 1 df, P< 0.01). To test for statistical differences within years and between groups, we used pairwise comparisons (Mann-Whitney U tests) for the daily prey delivery rates of one radio-marked individual and one control individual, both observed in the same year. Sample sizes are given in Table 1. Clutch-size and breeding success.--Clutch size and number of fledged young were compared between radio-tagged and control pairs in the col- ony. We pooled data from different years, as clutch size did not differ among years in control (H = 0.007, 1 df, P = 0.39) or radio-tagged pairs (H = 0.08, 1 df, P = 0.77). Similarly, there was no yearly variation in the Vol. 65, No. 4 Radio-tags on Lesser Kestrels [ 469 number of young fledged per pair between either radio-tagged (H = 1.17, I df, P = 0.27) or control pairs (H = 2.09, 1 df, P = 0.14). Annual survival rates.-•As breeding dispersal in the Lesser Kestrel is low and of short range (Negro 1991), those banded individuals that were not observed the year after their last sighting were considered dead. We therefore estimated minimum annual survival rates empirically as the per- centage of banded birds that returned from those present the previous year. The causes of mortality were unknown in most cases. One radio- tagged bird disappeared while wearing a transmitter, but was not relocat- ed. Return rates for subsequent breeding seasons were compared between radio-tagged and control individuals. We pooled the data for control birds from Mairena del Alcor and adjacent colonies within a radius of 30 km •, because there were no significant differences for return rates of adults between colonies (Negro 1991). We considered each year separately, how- ever, because return rates were statistically different for control birds (X 2 = 4.13, I df, P = 0.04), even though the differences were not significant for radio-tagged birds (Fisher's exact P = 0.59). RESULTS Of 14 radio-tagged individuals, 13 exhibited normal behavior within 1 h after release. One female left the colony for 24 h, however, during which its mate copulated with another female. When the radio-tagged female returned to the colony, it acted normally, expelled the intruder female and paired with its former mate (Negro et al. 1992). There were no significant differences between radio-tagged and control pairs, either in the duration of the copulation period (Mann-Whitney U test, Z = 0.75, P = 0.45) or in the estimated total number of copulations per season (Z = 1.17, P = 0.23) (Table 1). Both radio-tagged and control individuals exhibited similar prey delivery rates (Table 1). There were no significant differences (P > 0.05) in prey delivery rates for any of the pairwise comparisons between one radio-tagged and one control individ- ual. Considering two consecutive breeding seasons, there were no signifi- cant differences between the frequency of mate-switching for radio-tagged and control birds (Fisher's exact P = 0.19), the frequency of nest-switch- ing (Fisher's exact P = 0.16), or the frequency of colony switching (Fisher's exact P = 0.57). All these rates were slightly higher for radio- tagged individuals, however (Table 1). Clutch size (H = 0.54, 1 df, P = 0.46) and number of fledged young (H = 0.45, 1 df, P = 0.45) were not significantly different between radio- tagged and control birds (Table 1). Survival rates were also similar for radio-tagged and control birds in both 1989 (Fisher's exact P = 0.39) and 1990 (P = 0.47) (Table 1). DISCUSSION In some avian studies, the use of radio packages attached with back- pack harnesses decreased productivity and/or lowered the percentage of 470] F. Hiraldo et al. J. Field Ornithol. Autumn 1994 breeding pairs (Foster et al. 1992, Paton et al. 1991, Sibly and McCleery 1980, Warner and Etter 1983). As far as we know, however, there are no reports indicating negative impacts of tail-mounted radio-tags on avian reproduction. Sodhi et al. (1991) found no significant differences in re- productive output or hatching success of Merlins (Falco columbarius) wearing tail-mounted tags and untagged individuals. In our study, the reproductive variables (clutch size and number of fledged young) of Less- er Kestrel pairs with at least one radio-tagged individual were unaffected. We also found no differences in the duration of the copulation period, the number of copulations, or prey delivery rates to mates and chicks. These behavioral components have rarely been quantified in previous studies investigating the effects of radio-tags. Although the relatively small sample size of radio-tagged birds in our study may have limited the use- fulness of statistical comparisons, there was no indication of any serious problems associated with tail-mounted radio-tags. Current literature suggests that backpack-mounted radio-tags can sig- nificantly affect survival rates (Johnson and Berner 1980, Paton et al. 1991, Perry 1981, Warner and Etter 1983; but see Foster et al. 1992, Hines and Zwickel 1985). On the other hand, our study and work by Sodhi et al. (1991) indicate that tail-mounted radio-tags are less likely to affect survival rates. We conclude, therefore, that tail-mounted radio-tags, rep- resenting 3.0-3.5% of the body mass of the birds, did not significantly affect the social behavior, breeding success or survival of breeding Lesser Kestrels. Thus, we recommend the use of tail-mounted transmitters when- ever possible. Birds can lose them naturally when molting and are not at risk of becoming entangled or strangled, as with transmitters attached with harnesses. Tail-mounted radio-tags cannot be used on young birds, however, which leave the nest before the tail feathers are fully developed. Unless recapture of the birds under investigation is easy, tail-mounted radio-tags are also not particularly useful for studies involving long-term continuous collection of data, since they are lost when birds undergo their annual molt. ACKNOWLEDGMENTS We thank M. de la Riva for help in the field work, and D. Bird, M. Ferrer and two anon- ymous referees for revising the manuscript. The C.S.I.C.-C.I.C.Y.T. provided financial support (project PB87-0405), and one of the authors (JJN) benefitted from a predoctoral grant of the C.S.I.C. LITERATURE CITED BESKE, O. E. 1978. Harrier radio-tagging techniques and local and migratory movements of radio tagged juvenile harriers. M.Sc. thesis, Univ. Wisconsin, Stevens Point, Wisconsin. BmER, J.P. 1990. Action plan for the conservation of western Lesser Kestrel Falco naumanni populations. ICBP Study Report No. 41, Cambridge, United Kingdom. BRAY, O. E., AND G. W. CORNER. 1972. A tail clip for attaching transmitters to birds. J. Wildl. Manage. 36:640-642. CRAMP, S., ANt) K. E. L. S•MMONS (Er)s.). 1980. The birds of the Western Palearctic. Vol. 2. Oxford Univ. Press, Oxford, United Kingdom. Vol. 65, No. 4 Radio-tags onLesser Kestrels [471 DONAZAR, J. A., J. J. NEGRO, ANI) F. HIRALDO. 1992. Functional analysis of mate-feeding in the Lesser Kestrel. Ornis Scand. 23:190-194. , --, AND --'. 1993. Foraging habitat selection, land-use changes and popu- lation decline in the lesser kestrel Falco naumanni. J. Appl. Ecol. 30:515-522. FOSTER, C. C., E. D. FORSMAN, E. C. MESLOW, G. S. MILLER, J. A. REII), F. F. WAGNER, A. B. CAREY, AND J. B. LINT. 1992. Survival and reproduction of radio-marked adult spotted owls. J. Wildl. Manage. 56:91-95. GONZALEZ, J. L., AND M. MERINO (EDS.). 1990. E1 cernicalo primilia Falco naumanni en la Peninsula Ib6rica. I.C.O.N.A., Madrid, Espafia. 175 pp. HINES, J. E., AND F. C. ZWICKEL. 1985. Influence of radio packages on young blue grouse. J. Wildl. Manage. 49:1050-1054. JOHNSON, R. N., AND A. H. BERNER. 1980. Effects of radio transmitters on released cock pheasants. J. Wildl. Manage. 44:686-689. KENWARt), R. E. 1978. Radio transmitters tail-mounted on hawks. Ornis Scand. 9:220-223. MARKS, J. S., AND V. S. MARKS. 1987. Influence of radio collars on survival of sharp-tailed grouse. J. Wildl. Manage. 51:468-471. M(;CRARY, M.D. 1981. Effect of radio-tagging on the behavior of Red-shouldered Hawks. N. Amer. Bird Bander 6:138-141. NEGRO, J.J. 1991. Ecologia de poblaciones del cernicalo primilia. Ph.D. thesis. Univ. Sevilla, Sevilla, Espafia. --, J. A. DONAZAR, AND F. HIRAI.DO. 1992. Copulatory behaviour in a colony of lesser kestrels: sperm competition and mixed reproductive strategies. Anim. Behar. 43:921- 930. --, --, AND --. 1993a. Home range of lesser kestrels during the breeding season. Pp. 144-150, in M. IL Nicholls, and R. Clarke, eds. Biology and conservation of small falcons. Hawk and Owl Trust, London, United Kingdom. , , --, M. HERN/kNDEZ, AND M. A. FERN/kNDEZ. 1993b. Organochlorine and heavy metal contamination in non-viable eggs and its relation to breeding success in a Spanish population of lesser kestrels. Environ. Poll. 82:201-205. PATON, P. W., C. J. ZABEL, D. L. NEAL, G. N. STEGER, N. G. TILGH1VL•N, AND ]g. R. NOON. 1991. Effects of radio tags on spotted owls. J. Wildl. Manage. 55:617-622. PERRY, M. C. 1981. Abnormal behavior of canvasbacks equipped with radio transmitters. J. Wildl. Manage. 45:786-789. SIBLY, R. M., AND R. H. MCCLEERY. 1980. Continuous observations of individual herring gulls during the incubation season using radio tags: an evaluation of the technique and a cost-benefit analysis of transmitting power. Pp. 345-352, in C.J. Amlaner, Jr., and D. W. MacDonald, eds. A handbook of biotelemetry and radiotracking. Pergamon Press, Oxford, United Kingdom. SODHI, N. S., I. G. WARKENTIN, P. C. JAMES, AND L. W. OLIPHANT. 1991. Effects of radiotag- ging on breeding merlins. J. Wildl. Manage. 55:613-616. WARNER, R. E., AND S. L. ETTER. 1983. Reproduction and survival of radio-marked hen ring- necked pheasants in Illinois. J. Wildl. Manage. 47:369-375. Received 23 Jul. 1993; accepted 25 Oct. 1993. 

Efectos de radio-emisores de cola en cernícalos primilla adultos

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