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Abstract

POSTER • Size of horns in bovids has important and diverse biological implications and researchers have been trying to understand which factors determine this trait (Jorgenson et al., 1998; Giacometti et al., 2002) • In addition to factors, such as genotype, population density, habitat quality or climatology, anthropic actions like trophy hunting may also influence this phenotypic character (Coltman et al., 2003) • In our study we have used biometrical data from 1284 male Iberian ibex (Capra pyrenaica) hunted in Sierras de Cazorla, Segura y Las Villas Natural Park, southern Spain, during the period 1968 – 2004 • From 1988 to 1995 ibexes were not hunted because a drastic reduction of population density due to a sarcoptic mange outbreak; no data for 1998 were available; age of animals ranged from 7 to 15 years; in this National Game Reserve the most frequent strategy for ibexes harvest is trophy hunting which is focused to older males particularly in winter
LONG TERM MONITORING SIZE OF MALE IBERIAN IBEX TROPHIES
Jesús M. Pérez1, José E. Granados2, E. Serrano1*, Miguel A. Simón3, Ramón C. Soriguer4and P. Fandos4
1. Departamento de Biología Animal, Biología Vegetal y Ecología; Universidad de Jaén; Campus Las Lagunillas, s.n.; E-23071, Jaén, Spain,
2. Parque Nacional de Sierra Nevada; Carretera Antigua de Sierra Nevada, Km 7; E-18071, Pinos Genil, Granada, Spain,
3. Consejería de Medio Ambiente, Junta de Andalucía, Delegación Provincial de Jaén, Jaén, Spain
4. Estación Biológica de Doñana (C.S.I.C.); Av. María Luisa, s.n.; Pabellón del Perú; E-41013, Sevilla, Spain
* Current address: Equipe Ecologie des Populations, Laboratoire de Comportement et Ecologie de la Faune Sauvage, Institut National de la Recherche Agronomique
Chemin de Borde-Rouge– Auzeville, BP 52627, 31326, Castanet-Tolosan Cedex, France
Male Iberian ibex (Capra pyrenaica)
Photo by J. P. Crampe
Size of horns in bovids has important and diverse biological implications and researchers have been
trying to understand which factors determine this trait (Jorgenson et al., 1998; Giacometti et al., 2002)
• In addition to factors, such as genotype, population density, habitat quality or climatology, anthropic
actions like trophy hunting may also influence this phenotypic character (Coltman et al., 2003)
• In our study we have used biometrical data from 1284 male Iberian ibex (Capra pyrenaica) hunted in
Sierras de Cazorla, Segura y Las Villas Natural Park, southern Spain, during the period 1968 – 2004
• From 1988 to 1995 ibexes were not hunted because a drastic reduction of population density due to a
sarcoptic mange outbreak; no data for 1998 were available; age of animals ranged from 7 to 15 years;
in this National Game Reserve the most frequent strategy for ibexes harvest is trophy hunting which is
focused to older males particularly in winter
Bunnell, F. L. 1978. Horn growth and population quality in Dall shepp. Journal of Wildlife Management, 42: 764-775
Coltman, D. W., P. O’Donoghue, J. T. Jorgenson, J. T. Hoqg, C. Strobek and M. Festa-Bianchet. 2003. Undesirable evolutionary consequences of trophy hunting. Nature, 426: 655-658
Gaillard, J. M., J.M. Boutin, D. Delorme, G. Van Laere, P. Duncan and J. D. Lebreton. 1997. Early survival in roe deer: causes and consequences of cohort variation in two contrasted populations.
Oecologia, 112: 502-513.
Gaussen, H and F. Bagnouls. 1953. Saison seche et indice xerotermique. Université de Toulouse, Faculté des Sciences., Toulouse, France
Giacometti, M., R. Willing and C. Defila. 2002. Ambient temperature in spring affects horn growth in male Alpine ibexes. Journal of Mammalogy, 83: 245-251.
Jorgenson, J. T., M. Festa-Bianchet and W. D. Wishart. 1998. Effects of population density on horn development in bighorn rams. Journal of Wildlife Management, 62: 1011-1020
Location of the study area
Sierras de Cazorla, Segura and Las Villas
Natural Park (38º30’N–2º45’W)
Dependent variables were basal perimeter and length of horns (average of left and right ones)
• Climatological variables used were: mean temperature and rainfall during spring months (when
maximum horn growth occurs) and also mean temperature and rainfall values accumulated over
the entire animals life
• Both mean and accumulated values were highly corelated each other (r = 0.751, F = 1227.085,
p < 0.001) and, therefore they can not been used simultaneously in a multivariate analysis
• Horn growth was related sometimes to temperature (Giacometti et al., 2002) and to reinfall in
other ocasions (Bunnell, 1978)
• Therefore the Gaussen Index (GI) was calculated (Gaussen and Bagnouls, 1953; Gaillard et al.,
1997) (this index is defined as GI = Rainfall – 2Temperature)
• After reducing environmental information to a single variable (IG) we can use univariate
statistics, and this index is used as independent variable
• Each year class was treated separatedly
• Firstly we made a lineal corelation between horn length (HL) and horn basal perimeter (HBP)
with IG
• To make a comparison between years, we must exclude variability due to environmental factors
• As an example, in 1998 the rainfall reached 1500 mm and males aging 8 years culled during
this year averaged 67 cm for horn length; in 1999 the rainfall decreased drastically (800 mm)
and 8-yr males harvested during the year had an average horn length of 58 cm
•Thisdecreaseofhorngrowthispartiallyexplainedby thelowrainfalllevelandin orderto
assess a size trend we estimate horn size (length and basal perimeter) at a mean rainfall level of
1150 mm
• New length (corrected length) was then calculated according to the following equation:
Corrected HL: ObHL+ [(MR – IR)* ß]
ObHL= horn length observed (measured)
MR = mean rainfall through the study period
IR = rainfall rate assigned to each ibex according to its age and year of death
ß= slope of the regression line horn lenght (observed) versus reainfall (observed)
•Hornlengthwasmore sensible thanthehornbasal perimeter
• Then, we applied a lineal regression between corrected lengths and years to obtain the trend of
horn size due to factors other than environmental ones (e.g. density, harvest intensity, diseases,
variation in habitat quality)
• Drecrease of horn lenght through years was significant only in males aging de 10, 11, 12 and 14
years
Current work involves including data on ibex and livestock densities into the analysis
Trend of the corrected basal horn perimeter for 11 yr males
r= 0.236, F =13.44, p <0.001
r= 0.362, F =27.196, p <0.001
Trend of the corrected horn length for 11 yr males
r= 0.177, F = 4.54, p = 0.034
r= 0.049, F = 0.34, p = 0.561
Trend of the corrected horn length for 12 yr males
Trend of the corrected basal horn perimeter for 12 yr males
Jesús M. Pérez
Authors wish to thank the gamekeepers of the
Sierras de Cazorla, Segura y Las Villas Natural
Park for their valuable effort in obtaining data
Our research activity is partially supported by the
Plan Andaluz de Investigación (Junta de
Andalucía): RNM-118
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Article
Full-text available
Measures of horn growth of Dall sheep (Ovis dalli dalli) are compared with physical, demographic, and meteorological measurements. Horn growth is not correlated with body size in either ewes or rams. Rams showing rapid early growth of horn show slower subsequent growth. Gradual wear influences the measured length of the lamb annulus in both ewes and rams. Horn growth is a function of precipitation, implicating primary production, and shows marked differences between years. These differences appear to be correlated with recruitment. Horn growth of rams is more strongly affected by differences in environmental conditions between years than is horn growth of ewes. In good years, growth is enhanced uniformly over all ram age-classes; in poor years growth in younger age-classes is depressed more severely than is growth in older age-classes. Condition of the dam can affect horn growth of rams for a period of at least 5 years following birth. Useful indices of quality can be constructed from simple measurements such as length of annuli provided the lamb annulus is ignored and affects of calendar year are acknowledged. Measures presented argue for the importance of range quality in the production of trophy animals.
Article
Time- and sex-specific summer survival of roe deer fawns was estimated using capture-mark-recapture methods in two enclosed populations living in contrasting conditions. The population of Trois Fontaines (eastern France) was roughly constant in size throughout the study period, while in Chizé (western France), the population experienced frequent summer droughts and numbers decreased continuously during the study. Early survival of fawns was low and highly variable over the years at both Chizé and Trois Fontaines, and demonstrated marked variations between cohorts that need to be taken into account when modelling roe deer population dynamics. In Trois Fontaines, fawn survival was positively correlated with early body growth and total rainfall in May and June. In Chizé, fawn survival decreased with increasing density and tended to increase with increasing rainfall in May and June and adult female body mass. These factors explained more than 75% of the variability in early survival observed in both populations. Variation between cohorts had different consequences for the two populations. At Trois Fontaines, cohort variation was limited to a numerical effect on early survival. However at Chizé, cohort variation was long-lasting and affected the phenotypic quality of survivors at later ages, and thereby future survival and breeding abilities (both numerical and quality effects). Male and female fawns had similar survival over their first summer in both populations. This result contrasts with the lower survival of young males often observed in ungulates. Two ultimate causes can be proposed to account for the low and variable survival of roe deer fawns over the first summer: the high energy expenditures incurred by does during each breeding attempt and/or the low absolute body size of newborn roe deer fawns.
Undesirable evolutionary consequences of trophy hunting
  • D W Coltman
  • P O'donoghue
  • J T Jorgenson
  • J T Hoqg
  • C Strobek
  • M Festa-Bianchet
Coltman, D. W., P. O'Donoghue, J. T. Jorgenson, J. T. Hoqg, C. Strobek and M. Festa-Bianchet. 2003. Undesirable evolutionary consequences of trophy hunting. Nature, 426: 655-658
Location of the study area Sierras de Cazorla, Segura and Las Villas Natural Park
  • J T Jorgenson
  • M Festa-Bianchet
  • W D Wishart
Jorgenson, J. T., M. Festa-Bianchet and W. D. Wishart. 1998. Effects of population density on horn development in bighorn rams. Journal of Wildlife Management, 62: 1011-1020 Location of the study area Sierras de Cazorla, Segura and Las Villas Natural Park (38º30'N-2º45'W)