Multiannual Population Size Estimates and Mobility of the Endemic Pseudophilotes Bavius Hungarica (Lepidoptera: Lycaenidae) from Transylvania (Romania)
Total Page:16
File Type:pdf, Size:1020Kb
NORTH-WESTERN JOURNAL OF ZOOLOGY 10 (Supplement 1): S115-S124 ©NwjZ, Oradea, Romania, 2014 Article No.: 140101 http://biozoojournals.ro/nwjz/index.html << Fauna of the Romanian protected areas - A special issue in memoriam of Acad.Dr.Doc. Petru M. Bănărescu >> Multiannual population size estimates and mobility of the endemic Pseudophilotes bavius hungarica (Lepidoptera: Lycaenidae) from Transylvania (Romania) Andrei CRIŞAN1, Cristian SITAR1,2, Maria Cristina CRAIOVEANU1,2,*, Tibor-Csaba VIZAUER1 and László RÁKOSY1,2 1. Romanian Lepidopterological Society, str. Republicii 48, 400015 Cluj-Napoca, Cluj, Romania. 2. Department of Taxonomy and Ecology, Babes-Bolyai University, str. Clinicilor 5-7, 400006 Cluj-Napoca, Cluj, Romania. * Corresponding author, Cristina Craioveanu, E-mail: [email protected], Mobile Phone: +40 721 299178, Phone/Fax: +40 264 442467 Received: 03. September 2014 / Accepted: 12. November 2014 / Available online: 21. November 2014 / Printed: December 2014 Abstract. Pseudophilotes bavius hungarica is an endemic butterfly subspecies with high conservation value from Transylvania, yet its populations have not been consistently analysed. We assessed two fragments of a population of P. bavius hungarica from a botanical natural reserve and its surroundings with Mark-Release- Recapture method in the years 2004-2006, 2010-2012. The area considered to harbor one of the strongest populations known in Romania. Our study shows a fragmentation of the population and a tendency to decline in the number of individuals over the last 8 years as a result of abandonment of traditional management practices. The short lifespan (3 days) and low mobility (30 meters per day) of this butterfly negatively influences its dispersal capacity, which is aggravated by the spread of native and non-native shrubs (at a rate of 40% in 5 years), isolating population fragments. Keywords: natural succession; mark-release-recapture; population ecology; mobility; fragmentation; conservation considerations. Introduction 1992). One of the largest known populations in Transylvania is located in and around the botani- Food plant specialist Lycaenid butterflies are often cal nature reserve in Suatu (county Cluj). Histori- good indicators of habitat quality and therefore cally the population occupied the whole Bánffy some are threatened by habitat fragmentation and hill (which is included in a Natura 2000 site since degradation as a consequence of changes in land 2007), and is now restricted to two larger patches use (Erhardt 1985, Thomas 1991, Erhardt & Tho- of remaining suitable habitat: inside the nature re- mas 1991, Munguira et al. 1993, New 1993, Polus serve and on a patch of abandoned vineyard ter- et al. 2007, Thomas 2012). races outside the nature reserve. Observations on Pseudophilotes bavius is included in the An- this population began in 1977 in form of yearly nexes of the Council Directive 92/43/EEC on the observations (Rákosy 1983, 1999). The first Mark- conservation of natural habitats and of wild fauna Release-Recapture (MRR) studies in the nature re- and flora (annexes II and IV), in the Romanian leg- serve were conducted in 2004 (Vizauer & Adumi- islation (OUG nr. 57/2007 approved with troaie 2005) and 2005 (Vizauer et al. 2006). amendments by Law 49/2011 on the protected na- In this study we assessed the butterfly’s popu- ture reserves, natural habitats, wild flora and lation in order to see the effect of habitat reduction fauna), and in the Red List of Romania (EN) and its fragmentation in recent years and the effect (Rákosy 2002, Rákosy et al. 2003). Contrary to the of different land use (protected natural reserve classification in the European Red List (Van Swaay with no human intervention and extensively et al. 2010) it is probably more endangered than its grazed former vineyards) on its population size. threat category suggests due to habitat fragmenta- Additionally we registered other parameters tion and isolation of small populations (Van (flight distance, individual life span etc.) influenc- Swaay et al. 2012). Furthermore, the taxon P. ing its survival and dispersal ability. bavius hungarica (Diószeghy 1913) is an endemic The slope of the natural reserve was originally subspecies from Transylvania. The Transylvanian covered by a semi-natural grassland rich in relict- Blue is restricted to steppe-like habitats with like steppe species (Borza 1931, Resmeriţă 1971, abundance of the host plant Salvia nutans (König Cristea 1994). This habitat type can be considered S116 A. Crişan et al. as the continuation of the south Russian meadow (1971): Stipetum lessingianae, Salvio nutantis-Festucetum steppes. It was stabilized following the last post- rupicolae, Festucetum valesiacae-rupicolae, Botriochloetum is- glacial warmer period by removal of forests and chaemi and Carici humilis-Brachypodietum pinnati. In site B located in the abandoned vineyards following plant asso- traditional mowing and partly occasional grazing ciations were found: Salvio nutantis-Festucetum rupicolae, by cattle (Wendelberger 1985, Rákosy 2011). This Stipetum lessingianae, Carici humilis-Brachypodietum pinnati, type of land use was beneficial to most of the rare Pruno spinosae-Crataegetum and small patches of Prunetum and endemic species of plants e.g. Astragalus peter- tenellae. The distance between the two study sites is ap- fii, Salvia transsilvanica, Cephalaria radiata etc. (Res- proximately 1 km and they are partially separated by a meriţă 1971) and also for the development of a belt of shrubs of Crataegus monogyna, Prunus spinosa, Rosa sp. and dominated by Robinia pseudoacacia (Fig. 1). population of P. bavius hungarica and a high diver- sity of other Lepidoptera species (Rákosy 1999). Sampling methods A management plan developed by the nature MRR data from the years 2004, 2005, 2006 were collected reserve administration (Mihuţ et al. 2001) pro- in the nature reserve site (A) and in 2010, 2011 and 2012 posed in 2001 the alternating mowing of plots at from both the nature reserve site (A) and former vineyard site (B). Butterflies were captured every day (with excep- the end of the vegetation period, together with in- tions caused by unfavourable weather in 2004, 2005, 2006 stalling infrastructure to prevent access of cattle and 2010) between 9:00 A.M. and 7:00 P.M, between 21 and sheep to the nature reserve. However, just the April – 18 May 2004, 05-18 May 2005, 25 April – 20 May access of livestock was prevented and no alternat- 2006, 23 April – 11 May 2010, 18 April – 3 May 2011 and ing mowing treatment was applied in the follow- 26 April – 7 May 2012, on a regular basis by the same two ing period. We hypothesize that this lack of man- recorders in any one year, but different recorders from agement has lead to a significant decline of the year to year. Altogether 9, 7, 6, 10 (site A), 12 (site B), 5 (site A), 6 (site B) and 11 (site A) and 10 (site B) field trips population of P. bavius hungarica from Suatu (En- respectively, were conducted in the two study sites, in- yedi et al. 2008, Rákosy 2011) due to reduction of vesting the same time and effort in capturing and mark- suitable habitat. Furthermore, in order to stabilize ing, by both recorders. In the case of each cap- steep slopes in areas adjacent to the reserve, ture/recapture, sex of the captured individual, capture Robinia pseudoacacia plantations were established time and coordinates of the exact location were recorded. approximately 25 years ago. In the same period In the years 2010-2012 exact location coordinates were re- the natural expansion of autochtonous scrub spe- corded with a GPS device Garmin GPSmap 60 CSx. The sequence in which plots were inspected was alternated to cies such as Crataegus monogyna, Prunus spinosa, avoid systematic effects of time of day. Rosa sp. also contributed to the fragmentation of the former open steppe-like habitat with a barrier Statistical analyses between the natural reserve and the former vine- MRR data with over 5% recapture rates from the years yards. We verify the possibility of individual ex- 2004, 2005, 2010 and 2012 were analyzed to estimate the current population size, flight distance and average life- change between population fragments of P. bavius span of adults of P. bavius hungarica. Data were analysed hungarica and analyze the threat of their complete separately for site A in 2004, 2005, 2010 and 2012 and for isolation. site B in 2010 and 2012, with the Cormack-Jolly-Seber Based on these findings we propose a series of type constrained models (Schwarz & Arnason 1996; criteria for conservation management. Schwarz & Seber 1999) using the program MARK 6.0 package (Cooch & White 2010). The performances of the models were assessed separately for each site with the Materials and Methods Akaike Information Criterion corrected for small sample size (AICc) (Akaike 1973; Hurvich & Tsai 1989). As rec- Study sites ommended by Burnham and Anderson (2002), after run- Studies were conducted on the Bánffy hill in Suatu, 35 km ning predefined models in program Mark, we selected E of Cluj-Napoca (46°47’28” N, 23°57’59”). Two equal- the model with the lowest ΔAICc and the smallest num- sized sites (each 7500 m2), representing patches of suitable ber of parameters. The models considered to best ap- habitat for P. bavius hungarica, were selected, and each proximate the effects of factors supported by empirical were subdivided into 12 plots (each 25m x 25m) with high data, are the ones with AICc differing from the minimal density of S. nutans. One of the areas is located inside the one by less than 2. In 2010 the best fitted models did not natural reserve (site A) and the other on the vineyard ter- coincide for site A and site B. We did not select the same races (site B), which have been abandoned for 30-35 years, model for site A as for site B even though site A had a possibly longer, both with the same SW aspect and simi- smaller sample size.