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Spatial behaviour of Spanish Imperial Eagle Aquila adalberti juveniles during the dependence period revealed by high-resolution GPS tracking data

  • Rita F. RamosEmail author
  • João P. Silva
  • Carlos Carrapato
  • Pedro Rocha
  • Paulo A. M. Marques
  • Jorge M. Palmeirim
Original Article

Abstract

During the post-fledging dependence period, young raptors are particularly vulnerable as they are still developing flying, hunting and social skills, and collecting spatial environmental information required for emancipation. We studied the use of space during this critical period by the highly threatened Spanish Imperial Eagle Aquila adalberti, using high temporal and spatial resolution tracking devices. Ten juveniles from four different nests were tracked throughout their dependence period with GPS/GSM tags. This period lasted until a median age of 137 days (93–153). Juveniles remained within a stable home range with a median of 232 ha, but when 90–100 days old began making exploratory movements that became more frequent and extensive with the approach of emancipation. These movements had a median of 22.2 km and were usually completed within the same day, but this exploratory behaviour proved to be quite plastic, as one movement was 1291 km long and lasted 4.5 days. Moreover, three individuals that were apparently forced to emancipate particularly early seem to have virtually skipped the exploratory phase. The length of the movements varied among years within the same nest, and those of females were about twice those of males. Most movements were towards the NW, and the outgoing flight was usually against the wind. This behaviour may keep animals from flying so far from the nest that they are then unable to return. The high spatial and time resolution provided by GPS tracking resulted in data that highlight the conservation importance of the nest site until well after fledging. Measures to minimize nest disturbance should thus be extended until early October. Moreover, data show that so much of the activity of the still inexperienced juveniles is concentrated in the small pre-emancipation range that is critical to protecting its habitats and eliminating all anthropogenic sources of mortality.

Keywords

Aquila adalberti Exploratory behaviour Spatial ecology GPS tracking Dependence phase Iberian Imperial Eagle 

Zusammenfassung

Raumnutzungsverhalten von juvenilen Spanischen Kaiseradlern Aquila adalberti während der Abhängigkeitsphase anhand von hochauflösenden GPS-Daten

Die Phase der Abhängigkeit nach dem Ausfliegen ist für junge Greifvögel besonders prekär, da sie immer noch dabei sind, Fliegen, Jagen und Feinheiten des Sozialverhaltens zu üben sowie die für die Selbständigkeit notwendigen Kenntnisse ihrer Umgebung zu erwerben. Mithilfe zeitlich sowie räumlich hochauflösender Besenderungssysteme untersuchten wir die Raumnutzung beim stark gefährdeten Spanischen Kaiseradler Aquila adalberti während dieser kritischen Phase. Zehn Jungvögel aus vier verschiedenen Horsten wurden während ihrer Abhängigheitsphase mit GRS/GSM-Sendern ausgestattet. Dieser Zeitraum erstreckte sich im Mittel bis auf ein Alter von 137 Tagen (93 bis 153). Die Jungvögel blieben innerhalb eines stabilen Streifgebietes von im Schnitt 232 ha; im Alter von 90-100 Tagen begannen sie dann mit Erkundungsflügen, welche mit nahender Selbständigkeit häufiger und ausgedehnter wurden. Im Mittel erstreckten sich diese Flüge über 22,2 km und endeten in der Regel am selben Tag; allerdings erwies sich dieses Erkundungsverhalten als recht plastisch, denn ein Flug war 1.291 km lang und dauerte 4,5 Tage. Außerdem scheinen drei Individuen, die offenbar gezwungen waren, besonders früh selbständig zu werden, die Erkundungsphase praktisch übersprungen zu haben. Das Ausmaß der Flüge variierte zwischen den Jahren innerhalb ein und desselben Nestes und war bei den Weibchen etwa doppelt so lang wie bei den Männchen. Die meisten Flüge gingen nach Nordwesten und der Abflug erfolgte meist gegen den Wind. Diese Verhaltensweise könnte verhindern, dass die Vögel sich so weit vom Nest entfernen, dass sie nicht mehr zurückfliegen können. Die hohe räumliche und zeitliche Auflösung der GPS-Sender lieferte Daten, welche die Bedeutung von Schutzmaßnahmen für den Neststandort bis weit nach dem Ausfliegen unterstreichen. Maßnahmen zur Minimierung von Störungen am Nest sollten daher bis Anfang Oktober ausgedehnt werden. Die Datenlage zeigt zudem, dass sich ein derart großer Anteil der Aktivitäten der noch unerfahrenen Jungvögel auf das kleine Gebiet konzentriert, welches vor der Selbständigkeit genutzt wird, dass es von großer Wichtigkeit ist, die dortigen Lebensräume zu schützen und alle anthropogenen Mortalitätsfaktoren zu beseitigen.

Notes

Acknowledgements

Most of the GPS/GSM devices used were financed by the LIFE Imperial project (LIFE13 NAT/PT/001300)/European Union LIFE program and the Instituto da Conservação da Natureza e das Florestas, Portugal. Teresa Marques kindly provided statistical advice. Victor García Matarranz from Dirección General para la Biodiversidade/Ministerio de Medio Ambiente, Spain, provided invaluable assistance tagging the birds. JP Silva was funded by Fundação para a Ciência e a Tecnologia (FCT) postdoctoral grant SFRH/BPD/111084/2015. We are thankful to Miguel Ferrer and to an anonymous reviewer for suggestions that improved the manuscript.

References

  1. Alerstam T, Rosén M, Bäckman J, Ericson PGP (2007) Flight speeds among bird species: allometric and phylogenetic effects. PLoS Biol 5:e197.  https://doi.org/10.1371/journal.pbio.0050197 CrossRefGoogle Scholar
  2. Alonso JC, Gonzales LM, Heredia B, Gonzalez JL (1987) Parental care and the transition to independence of Spanish imperial eagles Aquila heliaca in Doñana National Park, southwest Spain. Ibis 129:212–224.  https://doi.org/10.1111/j.1474-919X.1987.tb03202.x CrossRefGoogle Scholar
  3. BirdLife International (2017) Species factsheet: Aquila adalberti. http://www.birdlife.org. Accessed 14 May 2018
  4. Bisson IA, Ferrer M, Bird DM (2002) Factors influencing nest-site selection by Spanish imperial eagles. J Field Ornithol 73:298–302.  https://doi.org/10.1648/0273-8570-73.3.298 CrossRefGoogle Scholar
  5. Bouten W, Baaij EW, Shamoun-Baranes J, Camphuysen KCJ (2013) A flexible GPS tracking system for studying bird behaviour at multiple scales. J Ornithol 154:571–580.  https://doi.org/10.1007/s10336-012-0908-1 CrossRefGoogle Scholar
  6. Chapman JW, Klaassen RHG, Drake VA, Fossette S, Hays GC, Metcalfe JD, Reynolds AM, Reynolds DR, Alerstam T (2011) Animal orientation strategies for movement in flows. Curr Biol 21:R861–R870.  https://doi.org/10.1016/j.cub.2011.08.014 CrossRefGoogle Scholar
  7. Dodge S, Bohrer G, Bildstein K, Davidson SC, Weinzierl R, Bechard MJ, Barber D, Kays R, Brandes D, Han J, Wikelski M (2014) Environmental drivers of variability in the movement ecology of turkey vultures (Cathartes aura) in North and South America. Philos Trans R Soc Lond B Biol Sci 369:20130195.  https://doi.org/10.1098/rstb.2013.0195 CrossRefGoogle Scholar
  8. Ferguson-Lees J, Christie DA (2001) Raptors of the world. Houghton Mifflin Harcourt, BostonGoogle Scholar
  9. Fernández M, Oria J, Sánchez R, Gonzalez LM, Margalida A (2009) Space use of adult Spanish imperial eagles Aquila adalberti. Acta Ornithol 44:17–26.  https://doi.org/10.3161/000164509X464849 CrossRefGoogle Scholar
  10. Ferrer M (1992) Regulation of the period of postfledging dependence in the Spanish imperial eagle Aquila adalberti. Ibis 134:128–133.  https://doi.org/10.1111/j.1474-919X.1992.tb08389.x CrossRefGoogle Scholar
  11. Ferrer M (1993a) Juvenile dispersal behaviour and natal philopatry of a long-lived raptor, the Spanish imperial eagle Aquila adalberti. Ibis 135:132–138.  https://doi.org/10.1111/j.1474-919X.1993.tb02824.x CrossRefGoogle Scholar
  12. Ferrer M (1993b) Reduction in hunting success and settlement strategies in young Spanish imperial eagles. Anim Behav 45:406–408.  https://doi.org/10.1006/anbe.1993.1048 CrossRefGoogle Scholar
  13. Ferrer M (1993c) Wind-influenced juvenile dispersal of Spanish imperial eagles. Ornis Scand 24:330–333.  https://doi.org/10.2307/3676796 CrossRefGoogle Scholar
  14. Ferrer M (1993d) Ontogeny of dispersal distances in young Spanish imperial eagles. Behav Ecol Sociobiol 32:259–263.  https://doi.org/10.1007/BF00166515 CrossRefGoogle Scholar
  15. Ferrer M, Harte M (1997) Habitat selection by immature Spanish imperial eagles during the dispersal period. J Appl Ecol 34:1359–1364.  https://doi.org/10.2307/2405253 CrossRefGoogle Scholar
  16. Ferrer M, Negro J (2004) The near extinction of two large European predators: super specialists pay a price. Conserv Biol 18:344–349.  https://doi.org/10.1111/j.1523-1739.2004.00096.x CrossRefGoogle Scholar
  17. Ferrer M, Newton I, Muriel R (2013) Rescue of a small declining population of Spanish imperial eagles. Biol Conserv 159:32–36.  https://doi.org/10.1016/j.biocon.2012.10.011 CrossRefGoogle Scholar
  18. Fisher NI (1993) Statistical analysis of circular data. Press Syndicate of the University of Cambridge, CambridgeCrossRefGoogle Scholar
  19. Forsman D (1999) The raptors of Europe and the Middle East. A handbook of field identification. Poyser, LondonGoogle Scholar
  20. González LM, Margalida A (2008) Biología de la conservación del Águila imperial ibérica (Aquila adalberti). Organismo Autónomo Parques Nacionales, Ministerio de Medio Ambiente y Medio Marino y Rural, MadridGoogle Scholar
  21. González LM, Margalida A, Manosa S, Sánchez R, Oria J, Molina JI, Caldera J, Aranda A, Prada L (2007) Causes and spatio-temporal variations of non-natural mortality in the vulnerable Spanish imperial eagle Aquila adalberti during a recovery period. Oryx 41:495–502.  https://doi.org/10.1017/S0030605307414119 CrossRefGoogle Scholar
  22. Greenwood PJ, Harvey PH (1982) The natal and breeding dispersal of birds. Annu Rev Ecol Syst 13:1–21.  https://doi.org/10.1146/annurev.es.13.110182.000245 CrossRefGoogle Scholar
  23. Hammer O, Harper DAT, Ryan PD (2001) PAST: paleontological statistics software package for education and data analysis. Paleontol Eletron 4:1–9. http://palaeo-electronica.org/2001_1/past/issue1_01.htm
  24. Hernández-Pliego J, Rodríguez C, Bustamante J (2014) Gone with the wind: seasonal trends in foraging movement directions for a central-place forager. Curr Zool 60:604–615.  https://doi.org/10.1093/czoolo/60.5.604 CrossRefGoogle Scholar
  25. Kenward RE (2001) A manual for wildlife radio tagging. Academic Press, LondonGoogle Scholar
  26. Kenward RE, Marcström V, Karlbom M (1993) Post-nestling behaviour in goshawks, Accipiter gentilis: I. The causes of dispersal. Anim Behav 46:365–370.  https://doi.org/10.1006/anbe.1993.1198 CrossRefGoogle Scholar
  27. Klaassen RHG, Hake M, Strandberg R, Alerstam T (2011) Geographical and temporal flexibility in the response to crosswinds by migrating raptors. Proc R Soc Lond B 278:1339–1346.  https://doi.org/10.1098/rspb.2010.2106 CrossRefGoogle Scholar
  28. Kovach W (2011) Oriana users’s manual version 4. Kovach Computing Services, PentraethGoogle Scholar
  29. Liechti F (2006) Birds: blowin’ by the wind? J Ornithol 147:202–211CrossRefGoogle Scholar
  30. Life Imperial (2017) Conservação da Águia–imperial-ibérica em Portugal. http://www.lifeimperial.lpn.pt/. Accessed 10 May 2018
  31. Mardia KV, Jupp PE (2000) Directional statistics. Wiley, LondonGoogle Scholar
  32. Martens FR, Pfeiffer MB, Downs CT, Venter JA (2018) Post-fledging movement and spatial ecology of the endangered Cape Vulture (Gyps coprotheres). J Ornithol 159:913–922.  https://doi.org/10.1007/s10336-018-1564-x CrossRefGoogle Scholar
  33. Mellone U, Limiñana R, López-López P, Urios V (2015) Regional and age-dependent differences in the effect of wind on the migratory routes of Eleonora’s falcon. Curr Zool 61:428–434.  https://doi.org/10.1093/czoolo/61.3.428 CrossRefGoogle Scholar
  34. Muriel R, Morandini V, Ferrer M, Balbontín J (2015) Independence and juvenile dispersal distances in wild and reintroduced Spanish imperial eagles. Biol Conserv 191:300–305.  https://doi.org/10.1016/j.biocon.2015.07.020 CrossRefGoogle Scholar
  35. Muriel R, Morandini V, Ferrer M, Balbontín J, Morlanes V (2016) Juvenile dispersal behaviour and conspecific attraction: an alternative approach with translocated Spanish imperial eagles. Anim Behav 116:17–29.  https://doi.org/10.1016/j.anbehav.2016.03.023 CrossRefGoogle Scholar
  36. Naef-Daenzer B, Grüebler MU (2016) Post-fledging survival of altricial birds: ecological determinants and adaptations. J Field Ornithol 87:227–250.  https://doi.org/10.1111/jofo.12157 CrossRefGoogle Scholar
  37. Newton I (1979) Population ecology of raptors. Buteo Books, VermillionGoogle Scholar
  38. Pavón D, Liminñana R, Urios V, Izquierdo A, Yáñes B, Ferrer M, de la Vega A (2010) Autumn migration of juvenile short-toed eagles Circaetus gallicus from southeastern Spain. Ardea 98:113–117.  https://doi.org/10.5253/078.098.0114 CrossRefGoogle Scholar
  39. Sarasola JH, Grande JM, Negro JJ (Eds.) (2018) Birds of prey: biology and conservation in the XXI centuryGoogle Scholar
  40. Shepard ELC, Wilson RP, Rees WG, Grundy E, Lambertucci SA, Vosper SB (2013) Energy landscapes shape animal movement ecology. Am Nat 182:298–312.  https://doi.org/10.1086/671257 CrossRefGoogle Scholar
  41. Steiniger S, Hunter AJS (2010) OpenJUMP HoRAE—a free GIS and toolbox for home range analysis. Wildl Soc Bull 36:600–608.  https://doi.org/10.1002/wsb.168 CrossRefGoogle Scholar
  42. Thorup K, Alerstam T, Hake M, Kjellén N (2003) Bird orientation: compensation for wind drift in migrating raptors is age dependent. Proc R Soc Lond Ser B 270:S8–S11.  https://doi.org/10.1098/rsbl.2003.0014 CrossRefGoogle Scholar
  43. Trivers RL (1974) Parent-offspring conflict. Am Zool 4:249–264.  https://doi.org/10.1093/icb/14.1.249 CrossRefGoogle Scholar
  44. Urios V, Romero M, Mellone U (2015) The use of satellite telemetry for the study of the movement ecology of raptors. Universidad de AlicanteGoogle Scholar
  45. Vidal-Mateo J, Mellone U, López-López P, De La Puente J, García-Ripollés C, Bermejo A, Urios V (2016) Wind effects on the migration routes of trans-Saharan soaring raptors: geographical, seasonal, and interspecific variation. Curr Zool 62:89–97.  https://doi.org/10.1093/cz/zow008 CrossRefGoogle Scholar
  46. Wakefield ED, Phillips RA, Matthiopoulos J, Fukuda A, Higuchi H, Marshall GJ, Trathan PN (2009) Wind field and sex constrain the flight speeds of central-place foraging albatrosses. Ecol Monogr 79:663–679.  https://doi.org/10.1890/07-2111.1 CrossRefGoogle Scholar
  47. Wood PB, Collopy MW, Sekerak CM (1998) Postfledging nest dependence period for bald eagles in Florida. J Wildl Manag 62:333–339.  https://doi.org/10.2307/3802296 CrossRefGoogle Scholar

Copyright information

© Deutsche Ornithologen-Gesellschaft e.V. 2019

Authors and Affiliations

  1. 1.cE3c—Centre for Ecology, Evolution and Environmental Changes, Departamento de Biologia Animal, Faculdade de CiênciasUniversidade de LisboaLisbonPortugal
  2. 2.CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Laboratório Associado, Instituto Superior de AgronomiaUniversidade de LisboaLisbonPortugal
  3. 3.REN Biodiversity Chair, CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Laboratório AssociadoUniversidade do PortoVairãoPortugal
  4. 4.Departamento de Conservação da Natureza e das Florestas do AlentejoÉvoraPortugal
  5. 5.Liga para a Protecção da NaturezaLisbonPortugal
  6. 6.MARE-ISPALisbonPortugal

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