Are Brown Bears Recovering in the Cantabrian Mountains? Reply to Ferna´ Ndez-Gil Et Al

Home , Cantabrian brown bear, Cantabrian Mountains, Somiedo Natural Park

SHORT COMMUNICATION N Palomero et al.

Are brown bears recovering in the Cantabrian Mountains? Reply to Ferna´ ndez-Gil et al.

Guillermo Palomero1,5, Increase in sampling effort 1,6 2,7 Fernando Ballesteros , Carlos Nores , Ferna´ndez-Gil et al. (2010) base their first criti- 1,8 3,9 Juan Carlos Blanco , Juan Herrero , and cism of our article (Palomero et al. 2007) on data 4,10 Alicia Garcı´ a-Serrano published in a previous book (Palomero et al. 2006:Fig. 1.3) that described the substantial in- 1 Brown Bear Foundation, Isabel la Cato´lica 13, E-39007 creases in observation effort (number of people Santander, Spain involved by the end of the year) during the study 2 INDUROT, University of Oviedo, Campus de Mieres, period in both Cantabrian populations. E-33600 Mieres, Spain In that book, we considered the possible effect of 3Department of Ecology, University of Alcala, E-28871 such an increase on the number of F located. Alcala´ de Henares, Spain CUB 4 Observation effort was significantly correlated with Ega Wildlife Consultants, Sierra de Vicort 31, 1u A, E-50003 Zaragoza, Spain the number of FCUB in the western population (WP; r 5 0.734, 16 df, P 5 0.002), but not in the eastern Abstract: We reply to the critique from Ferna´ndez- population (EP; r 5 0.195, 16 df, P . 0.1) (Palomero Gil et al. (2010) regarding our study on trends in et al. 2006:39). We also found that observation effort was significantly correlated with the total observa- female brown bears with cubs (FCUB)inthe Cantabrian Mountains, Spain (Palomero et al. tions of FCUB in the WP (r 5 0.808, 16 df, P , 0.001), 2007). We discuss the relationship between sampling but not the EP (r 5 0.0096, 12 df, P . 0.1). Hence, we concluded that ‘‘the greater effort applied in effort and the number of FCUB, the methods used to collect the data, and the relationship between the monitoring the WP involved an increase in the number of observations for each FCUB and better FCUB and the whole bear population. monitoring and verification of FCUB detected’’ (Palo- Key words: brown bear, Cantabrian Mountains, mero et al. 2006:39). Chao estimator, females with cubs, sampling However, we dispute the conclusion that the trend effort, Spain, Ursus arctos in FCUB was produced by increasing number of Ursus 21(1):125–127 (2010) observers for 2 reasons: (1) since monitoring started, a double observation network has existed consisting of a ‘Coverage Net’ and a ‘Survey Net’ (the former

increases the probability of detection of FCUB throughout the Cantabrian Mountains bear range); Our study of the trends in female brown bears and (2) in the WP, increases in other indices related (Ursus arctos) with cubs (F ) in the Cantabrian CUB to population size but unrelated to observation Mountains of Spain (Palomero et al. 2007) has been effort for the F were noted (see below). criticized by Ferna´ndez-Gil et al. (2010), who CUB To rule out the possibility that the increase in F question whether there really has been an increase. CUB was caused by an increase in sampling effort, we Their criticism focuses on 3 main aspects: (1) the suggested examining the dynamics of the F index increase in sampling effort during the study period; CUB after sampling efforts stabilised. We are also in the (2) unsystematic data collection and (3) the assump- process of examining whether other indices that did tion that the FCUB trend reflected the general not depend on sampling intensity (such as damage to population trend. livestock and agriculture) also increased in parallel

with the number of FCUB (unpublished data).

Unsystematic data collection [email protected] [email protected] 7cnores@ Ferna´ndez-Gil et al. (2010) consider our data uniovi.es [email protected] 9juan.herrero@ collection to be unsystematic and point out that our uah.es [email protected] data did not fit the analytical requirements.

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Although more rigorous protocols have been in teams provide different results. Since 1989, results place since 1994, it is true that the WP data was have been validated at a national coordination initially not gathered systematically. Hence, we meeting of all the teams working in the Cantabrian omitted data from 1989–1993 when assessing the Mountains (Palomero et al. 2006:24). Their concerns

FCUB trend for the WP (Palomero et al. 2007). Briefly about variability would be more applicable to results explained in Palomero et al. (2007), the method used from data collected prior to the inception of thereafter was described in detail in Palomero et al. standardised monitoring, such as those of Wiegand (2006:23). It consisted of a double information et al. (1998) and Naves et al. (1999). These used network consisting of a general ‘Coverage Net’ unconfirmed information from surveys, thereby

(CN) and a specific network for FCUB called ‘Survey raising the possibility that data were incomplete, Net’ (SN). The CN covered the entire brown bear heterogeneous, and not comparable among time distribution range and provided data on any bear periods or locations (Palomero et al. 2006:25). presence, including FCUB. It involved the public It is true that because the area was not sampled authorities’ ranger services, which were not specia- randomly, and because observers were instructed to lised in FCUB monitoring (around 80 rangers in WP obtain multiple observations on each FCUB once bear territory), as well as hunting association game- identified, data did not conform to the probabilistic keepers (approximately 40 in the WP), with the model underlying the Chao estimator (M. Harold- number of observers not changing substantially over son, US Geological Survey, Bozeman, Montana, the study. Palomero et al. (2006) only quantified as USA, personal communication, 2006). However, the observation effort the Survey Net, which came into trend for FCUB in Palomero et al. (2007) was obtained operation in 1989 in the EP and 1994 in the WP not from the Chao estimator, but rather from the

(currently 9 and 13 people, respectively). Members of observed FCUB. Therefore, we believe the trend we the SN were specialists in monitoring FCUB who report is a valid one even if assumptions were confirmed data on family groups provided by the violated in calculating the Chao estimator. Coverage Net and conducted their own surveys. Although the CN was not set up to conduct random sampling (members did not attempt to locate bears Did the trend in FCUB reflect a true according to any pre-established plan), one of their population trend? tasks was to inform the regional authorities of any Fernańdez-Gil et al. (2010) attributed to us the evidence of bear presence in their area of operations, contention that the FCUB trend reflected the true such as bear damage, FCUB, or other bears (for safety population trend in Cantabrian brown bears. No reasons, this included information about a bear in an such statement appeared in Palomero et al. (2007). area where hunting was scheduled). Thus, the CN We estimated that although the annual 3% rate of provided homogenous data coverage throughout the increase in FCUB in the EP was not statistically Cantabrian brown bear range for decades. significant, the statistically significant 7.5% rate of One indication that the CN provided balanced increase in the WP allowed us to assume that the information from the entire bear range even when the population was increasing overall. However, we do SN had few staff is that using both nets, we detected the not necessarily assert that the increase was 7.5%, most dispersing family groups in 1989–92 and 1993– merely that the finding of a significant regression of 96, when the SN was smaller. Subsequently, despite FCUB on time allowed us to conclude that the there being more observers in the SN, we noticed a loss population was increasing (l . 1). We assert that the of geographic distribution of peripheral FCUB and assumption that the FCUB trend generally reflected the concentration of FCUB in the most important breeding overall population trend was reasonable because, for areas (Palomero et al. 2007:Fig. 4). If the detected the overall population to have not increased while number of FCUB depended on the number of observers the FCUB did, other age and sex classes would have in the SN, fewer observers would have resulted in had to decrease. Fernańdez-Gil et al. (2010) do not observations being concentrated in the best known present information indicating that this was so. In areas, and the increase in SN would have made it easier fact, evidence exists to the contrary. Some of the to detect bears located in peripheral areas. abundance indices verified by Fernańdez-Gil and We do not understand Fernańdez-Gil et al. (2010) Naves (2007) suggest that bears in at least a part of the when they suggest that estimates for FCUB vary if WP increased during 1994–2006. While acknowled-

Ursus 21(1):125–127 (2010) SHORT COMMUNICATION N Palomero et al. 127 ging the difficulties involved in detecting temporary 2006), are based on incorrect interpretations of changes using abundance indices because of small Palomero et al. (2007), or are based on unsound sample sizes and large variances, they posited that methods. From a conservation perspective, their ‘‘scats appear suitable for considering trends because concern would be justified if our data on the partial they are the indices that are least dependent on changes recovery of the population contradicted those of in detectability’’ (Fernańdez-Gil and Naves 2007:23), other studies or if the results of our paper justified a and they found a significant trend of summer scat in reduction in conservation measures. Neither is the Somiedo Natural Park, one of the most important case: bears continue to enjoy the highest level of breeding areas in the WP, during 1994–2006 (r2 5 0.34; protection afforded by the autonomous regions, the P 5 0.04; Fernańdez-Gil and Naves 2007:11). Spanish State, and the EU, and efforts have been Fernańdez-Gil et al. (2010) suggest that an increased on the key issue of improving linkage increase in cases of infanticide might have induced between the two populations. some females to breed annually instead of biannu- ally, which would have led to an overestimate in the Acknowledgments number of FCUB. We have no evidence that infanticide We thank Ursus for giving us the opportunity to has truly increased in recent years, but if we analyse write this reply, R. Harris for editing the manuscript, the data again excluding FCUB whose cubs had died L. Ashcroft for correcting the English, and M. (1996, 2000, 2001, and 2004), we find a very similar Haroldson and C. Costello for comments on data trend (l 5 1.072; 95% CI 5 0.997–1.153; P 5 0.061) structure during the workshop Application of Count to that obtained when those animals are included of Females with Cubs to Small Bear Populations in (without the possible effect of infanticide, l 5 1.075; Pescasseroli (Italy) from 15 to 17 February 2007. 95% CI 5 1.002–1.154; P 5 0.043). The confidence intervals of these 2 estimates of l overlap. Literature cited Fernańdez-Gil et al. (2010) also point out that the FERNA´ NDEZ-GIL, A., AND J. NAVES. 2007. Ińdices de adoption of digiscoping may have increased the ability abundancia de indicios de los principales nućleos de osos to differentiate family groups, thereby increasing the en Asturias. Propuesta de protocolos. Resultados de las

FCUB, index. However, digiscoping began in 2004, and campanãs. 2004, 2005 y 2006. Estacioń Biolo´gica de so could not have affected the 1994–2004 time series. Donãna, Consejo Superior de Investigaciones Cientı´ficas Furthermore, Fernańdez-Gil et al. (2010) suggest that (CSIC)/Consejerıá de Medio Ambiente, Ordenacioń del Territorio e Infraestructuras, Principado de Asturias the increase of FCUB may be due more to good weather conditions than to a decrease in mortality, but they fail (Informe ine´dito), Spain. (In Spanish). ———, A. ORDIZ, AND J. NAVES. 2010. Are Cantabrian to provide any evidence. It would be interesting to bears recovering? Ursus 21:121–124. make a formal comparison of recent mortality with NAVES, J., T. WIEGAND,A.FERNA´ NDEZ, AND T. STEPHAN. 1999. that prior to the increase in population to shed light on Riesgo de extincioń del oso pardo canta´brico. La poblacioń this controversial point. Even if the increase in FCUB occidental. Fundacioń Oso de Asturias, Oviedo, Spain. were due to reasons other than a reduction in PALOMERO, G., F. BALLESTEROS,J.HERRERO, AND C. mortality, the increase would still be a valid one. NORES, EDITORS. 2006. Demografıá, distribucioń, gene´t- Fernańdez-Gil et al. (2010) cautioned that no ica y conservacioń del oso pardo canta´brico. Fundacioń other temporal window in the period under con- Oso Pardo/Direccioń General para la Biodiversidad, sideration revealed a positive trend. However, given Ministerio de Medio Ambiente, Madrid, Spain. (In that the significance of a correlation depends in part Spanish, with abstracts in English.) on the degrees of freedom of a time series, shortening ———, ———, C. NORES, J.C. BLANCO,J.HERRERO, AND a series length makes it increasingly unlikely that A. GARCIÁ-SERRANO. 2007. Trends in number and significant trends will be obtained. To ascertain distribution of brown bear females with cubs-of-the-year in the Cantabrian Mountains, Spain. Ursus 18:145–157. whether the population is recovering, an analysis of WIEGAND, T., J. NAVES,T.STEPHAN, AND A. FERNA´ NDEZ. longer, not shorter, time series is required. To do so, 1998. Assessing the risk of extinction for the brown it would be advisable to reanalyse the trend for FCUB, bear (Ursus arctos) in the Cordillera Canta´brica, Spain. adding information from after 2004. Ecological Monographs 68:539–570. In our opinion, the most important methodologi- cal concerns shown by Fernańdez-Gil et al. (2010) Received: 15 October 2009 either have already been dealt with (Palomero et al. Accepted: 8 February 2010

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