During 2019 a study related to Apollo butterfly’s conservation status at ‘Sierra de Guadarrama National Park’ -being included in IUCN Red List of Threatened Species as a vulnerable species and in ‘Catálogo de Especies Protegidas de Madrid’, as an endangered species-, has been hired by the National Park Authority. This project has been completed with the study of Prunner’s ringlet (Erebia triaria), Piedmont ringlet (Erebia meolans) and Black satyr (Satyrus actaea).
As it has been widely proven that the gradual increase in temperatures over the last few years can seriously affect and threaten mountain butterflies’ populations which are forced to take shelter at higher altitudes until no suitable habitat is available, the knowledge and monitoring of the conservation status of these species – bio-indicators of global change- is considered of great importance for the Research Centre of the National Park.
The main objectives of this study have been:
- For Apollo butterfly: location, mapping and census of the National Park’s population; assessment of the conservation status of the species and possible threats as well as actions proposed to prevent its decline and improve its conservation status.
- For the other mountain butterflies: obtaining specific and updated information related to their distribution and richness as well as elaborating precise maps with the information gathered, following Atlas methodology, already used in other National Parks.
The results obtained point out that Apollo butterfly’s conservation status is quite precarious. The majority of the territory studied which should be adequate for the species, has not been so. Only two colonies located seem to be the last strongholds of a bigger population that used to dwell in a wider area.
On the other hand, Nymphalides species’ (Ringlets and Satyrs) populations seem to be quite healthy and, for the moment, no threats have been detected. Their distribution and richness vary due to their particular ecological requirements and different flight periods.
Prunner’s ringlet (Erebia triaria) displays an earlier flight period and flies at lower altitudes. It has been located from the 20th of May to the 28th of June, when the last individuals were observed flying along with Piedmont ringlet’s (Erebia meolans) individuals. The peak in numbers was reached between the 10th and the 15th of June. Data come mostly from the northern areas between 1,500 and 1,900m a.s.l., with a maximum from 1,700 and 1,800m a.s.l.
Piedmont ringlet (Erebia meolans), in contrast to the previous one, dwells in high mountain altitudes, flying above 1,600m a.s.l., and prefers rocky ground and subalpine prairies above the tree line. During 2019 its flight period has been abnormally short, from the last week of June to the third week of July. This phenomenon has also been observed with the other ringlet and seems to be related to this year’s drought period, as grasses dried too soon and butterflies were forced to speed up their reproductive process.
This species does not seem to have any preference for Northern exposed slopes, most likely due to the fact that Erebia meolans flies at higher altitudes, closer to summits and crests where sunshine influence on temperature is less noticeable. Most of the data were obtained between 1,800m and 2,000m a.s.l.
Black Satyr (Satyrus actaea) is the one which starts to fly later and whose flight period lasts longer. Although previously absent in apparently suitable areas, it has been found in abundance, this year, well distributed along the most suitable areas, including several where Ragwort plants (Senecio jacobea) are plentiful. In those areas the satyr has presented very high densities as ragwort flowers provide a great deal of nectar, especially by the end of the flight period.
In 2019, its flight period has come ahead of time as the first individuals were registered on the third week of July and the last ones by the end of August. No individuals were detected in September.
Apollo (Parnassius apollo), has been located in two sites: the first with 30 individuals flying simultaneously, and the second with just 12. This year, the flight period has been from the end of July to the beginning of August, except for an area located in abnormally lower altitudes where the individuals were observed during the third and fourth week of June.
Other four historic sites were visited, two have not been visited for 12 years and the other two for 50 years. On the latter, no trace was found; apparently it has disappeared. On the first sites, the species has experienced a dissimilar evolution rate, whilst the most important Apollo population inside the National Park has thrived and presents high density and a good amount of reproductive females, the other one - located at the Peripheral Protection Zone- finds itself on the verge of extiction with barely 12 imagos -mostly male- occupying a very reduced territory where in 2007 more than 1,000 individuals lived.
The main reasons for this disappearance, the same ones that pose a threat to the existing colonies, are: visitors’ circulation, races and mountain biking, Spanish ibex (Capra pyrenaica) overpopulation, changes in vegetation, habitat alteration and small population size.
Just one of the few Apollo existing colonies at the National Park has enough entity to be considered ‘safe’ of threat. Nevertheless, another historic colony has declined to the brink of extintion in 12 years.
Taking into consideration all of the above, at the National Park we will continue working in broadening our knowledge about the four species and conducting conservation actions related to the protection of Parnassius apollo, such as: a) reinforcing sign posts indicating to stay on trails; b) including this considerations in Programs related to Spanish ibex population control; c) monitoring the population in order to avoid the loss of adequate habitat in favour of other vegetation unsuitable for Apollo’s requirements.
At present and with these data, ‘Sierra de Guadarrama’ Research, Monitoring and Evaluation Centre is working; Data that will be essential to elaborate a fragility study inside the Park’s territory.
Translation: Aurora de la Rosa