Aquatic Mammals 2007, 33(3), ##-##, DOI 10.1578/AM.33.3.2007.### Activity Patterns of the Mediterranean Monk Seal (Monachus monachus) in the Archipelago of Madeira Rosa Pires,1 Henrique Costa Neves,2 and Alexandros A. Karamanlidis3 1Parque Natural da Madeira, Quinta do Bom Sucesso, Caminho do Meio, Funchal 9064-512, Portugal 2Department of the Environment, Science and Culture, Municipality of Funchal, Praça do Município, Funchal 9000-072, Portugal 3MOm/Hellenic Society for the Study and Protection of the Monk Seal, 18 Solomou Street, Athens 106 82, Greece Corresponding Author: Rosa Pires, Parque Natural da Madeira; E-mail: [email protected] Abstract elephant seals [Mirounga leonina] [Hindell & Burton, 1988] and Hooker’s sea lions [Phocarctos Activity patterns of the critically endangered hookeri] [Beentjes, 1989]), time of day (e.g., Mediterranean monk seal (Monachus monachus) Weddell seals [Leptonychotes weddelli] [Lake were examined in the Desertas Islands Nature et al., 1997]), lunar cycle (e.g., harbour seals Reserve in the archipelago of Madeira. Activity of [Phoca vitulina] [Watts, 1993] and Galápagos fur seals at sea was recorded from 25 lookout sites seals [Arctocephallus galapagoensis] [Horning positioned along the reserve’s coastline and cor- & Trillmich, 1999]), ambient temperature (e.g., related to site location, season, time of day, and New Zealand fur seals [Arctocephalus forsteri] state of tide. From 1994 to 2005, monk seal activ- [Johnstone & Davis, 1987]), and state of tide (e.g., ity, related mainly to the reproductive behaviour Weddell seals [Bornemann et al., 1998] and har- of the species, was recorded primarily at the three bour seals [van Parijs et al., 1999]). pupping sites within the reserve. Activity was By contrast, very little is known on the activ- influenced by site location, season, and state of ity patterns of the Mediterranean monk seal tide but not by the time of day. Activity was high- (Monachus monachus). With fewer than 600 est during the autumn and winter months and was individuals surviving nowadays (Johnson related to the pupping and post-parturition neces- et al., 2006), the Mediterranean monk seal is sities of the species, and during high tide, when the considered to be critically endangered, with a incoming action of the sea led monk seals to move high risk of extinction over the next three gen- out of coastal caves, which are used for resting erations (Baillie et al., 2004). Its distribution and breeding. Differences in activity among the range contracted severely in the past century, three sites monitored were attributed to the level and Mediterranean monk seals survive now only of protection offered by these locations against in small, isolated colonies distributed over the wind and wave action. The findings of this study, archipelago of Madeira, the Cabo Blanco region the most extensive study of its kind, have enabled in the Western Sahara, and the Mediterranean the identification of priority research, and conser- Sea where they occupy remote, coastal caves vation actions for the species in the area. (Johnson et al., 2006). The species’ endangered status, cryptic nature, and the inaccessibility of its Key Words: Mediterranean monk seal, Monachus habitat have prevented long-term research efforts monachus, population estimates, pupping sites, and the wide-scale application of effective but seasonal activity, species conservation, tidal influ- invasive research methods such as radio-telem- ence, Desertas Islands Nature Reserve etry to study its activity patterns, either at sea or at land. Short-term studies have indicated that the Introduction activity of Mediterranean monk seals in Greece, Turkey, and the Western Sahara is influenced by Activity patterns of several pinnipeds have been the season (Dendrinos et al., 1994, 1999), the state the subject of intense scientific research and of the sea and tide (Marchessaux & Muller, 1987; have provided valuable insights into their life González et al., 1997, 2002), and/or the time of strategies while promoting their effective moni- day (Dendrinos et al., 1994; Güçlüsoy & Savas, toring and protection (Costa & Williams, 1999; 2003; Gucu et al., 2004). Dendrinos et al., 2007a). Seal activity has been The Desertas Islands are the last stronghold of related to various factors such as season (e.g., the Mediterranean monk seal in the archipelago 328 Pires et al. of Madeira (Reiner & dos Santos, 1984; Pires et weather conditions (i.e., below a Beaufort scale al., in press). In order to protect the species, the of three or four). islands were declared the Desertas Islands Nature In our study, we examined the relationship Reserve (DINR) in 1990, and are managed by between monk seal activity and location, season, the Parque Natural da Madeira Service (PNMS). tidal state, and time of day. Seasonal activity The present study was carried out within the was classified as winter (W: 21 December to 20 framework of the Monk Seal Conservation and March), spring (S: 21 March to 20 June), summer Monitoring Programme (MSCMP), carried out (Sm: 21 June to 22 September), or autumn (A: 23 by PNMS in the area (Pires et al., in press), and September to 20 December). Tidal state was clas- quantified Mediterranean monk seal activity at sea sified as high (HT) or low (LT) if the time was (i.e., the occurrence of a seal at sea) in the DINR one and a half hours before or after the peak of and examined its relationship to a number of envi- the respective tide, whereas intermediate periods ronmental factors. We hypothesized that activity were classified as flood (FT) or ebb (ET) tide. of monk seals would be influenced by site loca- Activity could be recorded systematically only tion, seasonality, state of tide, and time of day. The during daytime, which was classified as morn- aim of the study was to identify which of these ing (M: 08:00 to 11:59 h), midday (MD: 12:00 to factors influence monk seal activity and determine 15:59 h) or afternoon (A: 16:00 to 19:59 h). Each the effect their different levels have on it. individual seal sighted within an hour of monitor- ing effort was counted as one sighting, and monk Materials and Methods seal activity was evaluated based on the sighting rate (SR = total number of sightings/total hours Study Area of effort). Individual identification was based on The Desertas sub-archipelago comprises three external morphological features such as pelage islands (Ilhéu Chão, Deserta Grande, and Bugio) colouration, scars, and wounds. Age class and located 11 miles southeast of the island of Madeira gender of individual monk seals were determined (16° 28' to 16° 33' longitude west, 32° 24' to 32° based on morphological characteristics described 35' latitude north) (Figure 1). The 37-km long by Badosa et al. (1998), Dendrinos et al. (1999b), coastline is composed mainly of steep, inacces- and Samaranch & González (2000). In the statisti- sible cliffs with several beaches and caves. The cal analysis, only the minimum number of posi- islands are uninhabited, with the exception of the tively identified individuals was used. PNMS station at Doca, where the park personnel reside. The reserve boundary is defined by the 100- Data Analysis m depth isobath. The entire northern half of the General Linear Model (GLM) fitting techniques were protected area has the status of a partial reserve, used in order to understand the relationship between where human activity, including fishing, is con- the sighting rates of Mediterranean monk seals in trolled; whereas, the southern half has the status of relation to the variables recorded. A logarithmic a strict reserve, where all human activities, except transformation was applied to the dependent variable scientific research, park management actions, and in order to homogenize variances and site location, traditional tuna fishing, which is not considered to season, state of tide, and time of day were entered as present a threat to monk seals, are prohibited. fixed effect factors to the analysis. Observation effort was used as a weight, hence accounting for varia- Data Collection tions in the duration of observation effort through- This study was part of a strictly non-invasive mon- out time. A custom forward stepwise method, start- itoring project carried out by PNMS and includes ing with the null model with a single intercept, was data collected by the research personnel and used to produce candidate models. At the first step, wardens of the PNMS from 1992 to 2005. Seal each of the four factors recorded was added to the activity was recorded only at sea from 25 lookout null model. If its p value was less than 0.05, then the sites where the inspection of potential pupping model with the additional variable was considered to and/or feeding sites (i.e., areas with caves and/or explain more of the variability in the dependent vari- rocky bottoms, shoals) was possible (Figure 1). able than a model without the variable. The factor From the lookout sites, and aided by binoculars, causing the highest deviance reduction was kept. At the surrounding marine area was surveyed and each following step, a factor was added, and its main the number of individual seals sighted at sea was effects and two-way interactions were tested. Again, recorded. Access to these lookout sites was only the combination of significant factors and interac- possible by sea. Due to the remoteness of the tions causing the highest deviance reduction was study area and in order to guarantee the security of kept. The process was terminated when the addition the wardens and research personnel, monitoring of a factor and possibly its interactions was no longer efforts were carried out only under favourable significant. Mediterranean Monk Seal Activity 329 Figure 1. Map of the Desertas Islands Nature Reserve (DINR), indicating the names and locations of the lookout sites mentioned in the text 330 Pires et al.