💾 Archived View for magda.cities.yesterweb.org › oblog › 2024-april-18.gmi captured on 2024-08-18 at 17:19:19. Gemini links have been rewritten to link to archived content
⬅️ Previous capture (2024-05-10)
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Because weather condidtions are unlikely to improve until the end of the month, I've already started to work on this month's summary. At the time of writing this, the town nearbly sent out their low-paid workers to mow the meadow in front of my home to get their (admittedly hideous) "English lawn" back. Because this area already only attracted three A. io overall, it likely will not be mentioned often in my season summary, in fact the species composition is so sparse, despite clear signs that "nature" wants to reclaim it, that I tend to avoid it altogether once they start their highly-irregular mowing season, which always leaves the majority of the bare soil underneath exposed and thus makes it prone to a high degree of erosion and outright droughts (even during wet years, the remaining grasses turn to hay and some trees start to struggle for nutrients).
This strange mowing regime, unfortunately, also extends to parts of my main study area. Last year was a particularly bad year for P. napi due to the mowing season's starting location being the area right between the "mixed field" and "Zone I", where an ancient drainage ditch was reclaimed by garlic mustard, a plant on which both P. napi and A. cardamines heavily rely on during their respective caterpillar stages, many bushes and young fruit trees right behind the ditch were cut – "cut" actually is an unfitting term; many branches appeared to have been ripped off and were dropped in the cleaned ditch – and thus contributed to the uncontrolled spread of orchard grass, which reduced the amount of other nectar-producing flowers. To me, it was quite shocking how such a routine can have a devasting effect on biodiversity.
Back when I still was a toddler, things actually looked even worse. The northernmost part of what constitutes Zone II used to be a dumpster. While no one would be able to tell at there used to exist such a thing nowadays, it took the area at least 10 years to even start to recover properly. As a kid, my parents and I often visited "David's fields" and at no point did we observe any insects and birds were sparse, too. Plant-wise, I don't remember having seen any flowers; even chicory was something quite rare. After the dumpster was closed and demolished, various spots nearby were used as illegal dumpsters, including the southeasern brink of the FFH territory "bog hill" (which also was abused by a former classmate of mine and his brother as an illegal motocross track).
Because my research only began in 2022, I am unable to tell when each area exactly began to recover from decades of exploitation and destruction, however I still get to witness species entirely new to this area with each observation season, it is likely that the current species composition began to establish itself within the last ten years and struggled undeniably during the droughts in2018 and 2022.
Still, many species considered "common" to "very common" still are missing entirely or are a much rarer sight than official lists for my state always imply to not be the case. Things are even harder to judge appropriately due to the few volunteers that kept track of species in my valley suddenly no longer providing data since last season, iNaturalist remaining just as unpopular and unknown to the vast majority of people as before and NABU never publishing a comprehensive list of all species observed by volunteers during their annual "butterfly counting day".
Ironically, this is one of the few species I wouldn't consider truly native to my area. Histroic and recent records indicate that it doesn't have a stable population outside of a single transect near Jena, which it has only left to travel to other places across the state at rare occassions starting from the 1930's up until the early-60's. Outside of its main transect, it did not show a clear preference for a specific biotope and, especially within my valley-like area, avoided large areas to travel to a spot further north, which – and even back then – was no different than from my region. The vast majority of observations rather indicate a behavior more similar to other migrant butterflies such as V. cardui, which only appears during so-called "invasion years". The state of Brandenburg historically was not claimed by I. podalirius and only introduced itself within the last decade, with scientists suspecting its migration to northern states to be a result of climate change. As there's no reliable data available for Brandenburg or any other state north from mine available, only the little data for my region may offer some insight – it never was observed here but may or may not show up in the future.
Neither does my area lack its preferred nectar plants, nor its favorite hosts. Data from my nearest transect, which hasn't been updated since late-2022, indicates that it has last seen in 2014 and then just disappeared entirely. Its sudden disappearance may be explained by its preference for mediterranean/sub-tropic temperatures.
Profiting from global warming, this species has already been observed at locations several kilometers north from my village, though no observations have been made at said locations since 2022, indicating that most observed populations are instable and currently behave like "random quests". Just like A. crataegi, it probably is avoding my area due to the average temperatures being too cool.
Unlike P. mannii, P. edusa has made recent appearances close to my study area, though not anymore after 2022. It thus seems to profit off droughts and avoids areas that aren't very arid. As my study area tends to be a little more on the humid side of the scale, I personally doubt that it will make an appearance at either my main zone or the boh hill, which largely lacks nectar plants.
The only migrating butterfly that technically should have showed up during both droughts but didn't. It was last seen in 2020 several kilometers north from my village.
Because the current Status quo does not list this species separately and rather considers it a species complex consisting of three different types of which only two are suspected to be native to my state, official records are a mess. Apparently being stable at the same spot C. crocea showed up the last time, L. sinapis/juvernica was last seen roughly six kilometers southeast from my village in 2021.
The lack of this species within my study area even surprised my friend from Austria because my area theoretically should be ideal. It turns out that its distribution within my valley is fairly unequal and during this season only has been observed near a small town close to Weimar. One thing almost all oak trees have in common is the lack of branches below three meters above the ground, which makes possible observations nearly impossible, yet even observing the crowns, which I have been doing, does not even hint the possibility of an adult population existing within my study area. Plenty of young oaks, which can be studied for eggs with ease, do not host any eggs of F. quercus.
Another case similar to that of F. quercus, it is being observed close to Weimar, yet hasn't been seen close to my area since its last observation in May, 2021. Already hard to miss due to its color, there's no explanation for its avoidance of the majority of the valley.
Another species seemingly avoiding larg parts of the valley and only having been a rather recent newcomer at few spots.
Disappeared prior to 2020 from my district.
Lat seen prior to 2020 near the town south of my village, available data is too inconsistent to make any claims about its state within my district. Poissible reason for its extremely rare appearances may be the lack of its host ant.
Disappeared between 1981 and 2000 with its last observation in my state dating back to 2018.
Its last remaining populations in my valley are situated close to Weimar and Erfurt.
Its local population disappeared suddenly after June, 2021. So far, there are no signs of this species recovering from the drought in 2022.
This species is interesting insofar, as it began to appear in the 1990's and disappeared again around 2010. It thus is highly unlikely to return, despite one observation in 2022 at the bog hill still being indefinable. Because no ther area closeby has documented this species, it likely either was a regional variation or the officially-recognized sub-species of P. icarus.
Just two hours ago, my front door was covered in cowslip that just wanted to start to bloom. Every single flower got mowed down and now the remaining indivuals are located in my yard (two individuals) and in different parts of Zone I (also two individuals). While the recent appearance of cowslip makes it more likely for H. lucina to show up in the future, I would not count on it and especially not during this and next year's season.
They don't seem to like asphalt all that much. Both can be observed on the other side of the forest north of my village, however they likely will not settle nearby, now that cyclicts demand more asphalt roads for their bikes.
Just like A. iris and A. ilia, it doesn't appear to like asphalt.
Close to Weimar. It was last seen prior to 1981 in my area.
Very common everywhere but very rare over here. It was last observed in 2022 near Erfurt.
Disappeared prior to 2000 and its only stable populations are located near Erfurt and Weimar.
Largely having disappeared prior to 2020, it was last observed near the town south of my village in July, 2021.
Another species which doesn't appear to be truly native but was occassionally observed in the past.
All records of this species end around 2020, yet there still is a possibility that I observed a lone individual of this species at the bog hill in 2023. Since no other Melitaea sp. was recorded after 2000, this likely is the case, yet still makes it such a rare observation that it either is just rediscovering my area or simply made a surprise visit. This is one of the few species I'll keep a close eye on.
Possibly also just a guest that briefly appeared in some regions, it is unlikely to return to my area, in which it was last seen prior to 1981.
Available data is insufficient to draw conclusions but it was last seen near the town south of my village in May, 2020.
Nearby transects last recorded its presence in October, 2021, and its first observation dates back to 1995.
Historical data implies that this species was not observale in my district until 1988. It was last seen in 2022 several kilometers north from my village.
Overall, 29 species theoretically should appear within one spot of my study area. Discounting M. aurelia, which I may have observed in 2023, typical migrating butterflies and P. thersites, which disappeared just as fast as it started to appear, this reduces the number of missing species to 26. Since many species lack sufficient data to determine how native/stable they truly may be to my area and whether they are closer to typical migrating butterflies. Merely judging by the current species compositon, changes due to climate change are negligible and the most important factor influencing it is local land use. Remembering that the only butterflies I ever got to see in my parents' garden were V. atalanta, P. rapae and P. brassicae when I was still a child, the recent species composition still is a significant improvement to my village's surrounding area. The only area in which the opposite is the case due to mismanagement carried out by "nature conservation" groups is the bog hill which was intentionally overgrazed to restore its presumed "natural steppe" (while its name used by people from my village always has implied this area to be the opposite of a steppe prior to the Nazi era; drainage was not practiced over here until 1924 and areal shots from 1956 indicate that this spot once hosted a few tiny fields before someone decided to turn its western brink into a tiny meadow orchard, which then got partially wiped and then abandoned by said conservation group).
It remain to be seen whether one of those species (re-)claims my study area. At least the main zones offer some spots that are suitable for some of them.