Diario del proyecto Noctuidae - above 2000m in the Swiss Alps

04 de mayo de 2021

my contribution to this (1974-1978)

... observing moths at altitudes over 2000m is an interesting undertaking. Hiking during the day will reveal some day active ones, but that's only a small fraction. Attracting them by light seems more efficient. However, it acually isn't. You may find yourself outside in a cold night, even in plain Summer, and very few moths may arrive. Statistics on my observations reveal, that an average night (median) would yield only 23 individuals of Noctuidae, grouped in 3 species. That doesn't sound very appealing, does it? If you knew how to pick one of the top 10% of all nights, you might end up with 275 individuals, grouped in 23 Noctuidae species. Looking for many nights at >8 locations during >3 years gave a total of around 120 species of Noctuidae. Most of them only occurred in a few nights only. Species can be put in three main groups: (1) the migrating moths, which regularly appear, but in hugely varying numbers, (2) the very interesting high altitude endemics and (3) the endemics from lower elevation areas which for some reason appear occasionally.

To characterise my observations from that time, I put them into a spreadsheet. Mainly to calculate diversity and rarity indices. An example is given below, showing the inverse Simpson index, a measure for diversity, which also corresponds to "effective" number of species. Simpson index is the probability that two entities taken at random from the dataset of interest represent the same type. Details see https://en.wikipedia.org/wiki/Diversity_index .


This shows the values for each location. Location name in black means =unattended light trap, location name in red means =attended moth observation. The value "effective species" = 1/(Simpson index).
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This shows the most often observed Noctuidae species. Apamea is the sum of A.zeta and A.maillardi. "ind/eff" is the number of individuals divided by effective nights, a measure for intense biomass appearance, mostly seen with migrating species.
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This shows the best nights in terms of species number.

Anotado en mayo 04, martes 16:28 por amzamz amzamz | 0 comentarios | Deja un comentario

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