biologe

Blog and online journal with editorial content about science, art and nature.

Tag: park

Reawakening at very early spring

Morning mist

Forest in the morning, tree stems covered by a foggy most, borderless steam wraps slowly rising in the air and disappearing there tracelessly.

Forests as moisture reservoir, being released in the morning due to the awakening warmth. Morning mist is nothing else than a fog, only some meters over the ground. Consisting like each fog of numerous water bodies in gas conditions, which condensate due to the cold night and seem to have springled all plants and even insects and other sleeping animals with tiny water drops.

Especially in arid environments, that morning mist watering is most wanted and essential for surviving.

With the rising sun, warmth moves the misty clouds up, where they cover the forests in a mysterious light, before the fog disappears.

Sunlight

Consisting of all rainbow colors, each color of the spectrum being defined by a specific wave length. But sunlight also consists of physical components, particles, called solar wind.
Light as essential source for life on earth, sunlight as energizer, basis for the production of oxygen. Warmer sun beams as reawakener of a sleeping forest.

Blooming

They bloom most early in the year, do not avoid to attract early insects inmidst of snow layers: snowdrops, winter aconites and crocuses.

Snowdrops (genus Galanthus) generate thermal energy due to the absorption of sunlight. This energy is essential for growth processes in cold environments.

Winter aconites (Eranthis hyemalis) have their blossoms only opened in the sunlight. Blossoms are closed over night. Opening and closing are temperature dependent growth processes. The blossoms themselves are resistant against cold. When temperatures rise to 10 – 12 degrees, first honey bee visits can be observed.

In crocuses (genus Crocus) blooming depends on the availability of moisture and warmth. Some species bloom in autumn, others in the late winter period.

All early blooming plants save nutrients as energy resources in tubers or bulbs.

Blue hour

When the sun disappears behind the horizon, an explosion of colors in red or yellowish cover the sky. In fact indicating the end of a day, in some cultures even officially a new day was dawning, when the sun disappeared, such as in Judaism, Islam or ancient Germanic peoples.

Saying „the sun is setting“ is a relict of a geocentric model of perspective. Not the sun is moving, but the observer.

When the sun is far enough underneath the horizon, the blue light spectrum dominates and creates a shiny blue sky, forming a photogenic contrast to the silhouettes of trees and landscape structures.

Moon

The only recent Trabant of our earth, presumably sirvivor of two or even several natural earth satellites in early times of our solar system.

Reflecting sunlight at night, lightening up the sky in the dark. Orientation aid for nocturnal animals, especially insects. Rhythm generator for the reproduction periods of numerous organisms.

The only extraterrestrial body that was so far ever visited by human beings. The first, which might be colonized before Mars.

All copyrights Stefan F. Wirth, Berlin March 2021

The details about snow

Misty

In former times, when people lived in a mystic world, where elves, dwarfs, leprechauns and talking wolves did their dreadful state of affairs in the midst of dark and impenetrable huge forests, people thought that even the old trees in the woods had their own thoughts.

Park Rehberge in Berlin

Uncontrollable, sounds, the snorting of the deer, a mysterious hidden, permanently changing shades in a cold and misty twilight.

Biology

A forest is only then a forest, when a high concentration of trees is given. Woods bear a great number of species, produce a majority of oxygen in our world; they are huge reservoirs of water and stabilize the ground with their tangles of roots.

Snow

Snow consists of ice crystals. Their formation within clouds depends on the presence of ice nucleating particles and temperatures lower – 12°C.

Crystals possess a hexagonal symmetry, being prism-shaped at lower temperatures and dendrite-shaped at higher temperatures.

Temperate deciduous forests hibernate without functional leaves. Most trees throw off all leaves already in autumn to be protected from desiccation in winter frost periods.

Layers of snow are excellent thermal conductors and additionally protect all life underneath from frost damages in the cold season.

Waiting for the spring time

Most life forms hibernate together with their leafless trees. Especially accumulations of deadwood contain remarkable numbers of species, such as insects, spiders, mites or nematodes. Some already begin under their snow cover to prepare themselves for the warmer season.

When all snow is gone, winter colors in red, yellow, brown and some green reappear. Early blossoming plants are already germinating.

Linyphiid spider visits much bigger snail and bites into mucus

During a photo shooting with a specimen of the snail Arianta arbustorum in an evening outdoors in urban park Rehberge in Berlin with artificial light from an extra lamp and camera LED light, a tiny spider of Linyphiidae (seemingly Bolyphantes sp., may be still a juvenile) appeared unexpectedly and walked seemingly targeted to the snail’s head, which was partly retracted into its shell, and stayed there for about 3 minutes, biting repeatedly into the snail’s mucus and remained subsequently each time for seconds in that position. In between it skillfully and repeatedly rearranged the positions of its legs, presumably to be not in danger to remain stuck.

While doing so, it sometimes lifted legs, when not needed, in the air, may be to reduce that way the probability to remain stuck. After about 3 minutes the spider left its position around the snail-head mucus and walked partly sidewards to the top of the shell, where it carefully cleaned its legs from remaining mucus. Due to the difficult light conditions and the unexpected spider visit, I was in this short time unable to move the camera closer to the spider (would have been technically possible, when more time and more light). Thus-close-ups with a high magnification in my video were only due to digital magnifications out of the original 4K footage. Only one biting action could be clearly documented as video file. The same short scene is in my video three times repeated to exemplify that behavior.

Spider visiting a snail, in order to incorporate mucus? Berlin May 2020, copyrights Stefan F. Wirth

The last repetition is additionally modified into slow motion. There was furthermore no video footage of legs adjusted in the air. Thus the corresponding short scene is one of numerous photos, which I captured before filming. It is unknown to me, what the purpose of the spider’s behavior was. I also did so far not find any scientific publication mentioning tiny spiders visiting much bigger snails on purpose. It looked to me as if the spider would incorporate mucus or moisture or other components excreted by the snail. I do not know, whether such a spider behavior happens regularly or at least occasionally, as I only have this one observation. I would exclude the possibility that the spider was disturbed by my photo activities in its web may be in the adjacent meadow, tried to flee and accidentally landed on the snail and just observed this unusual surrounding with its mouthparts. All looked too much like a targeted behavior with even specific behavioral adaptations. There is generally not much known about spider and snail interactions. The scientists Nyffeler and Symondson (Bern, Switzerland) published in 2001 about malacophagy in the sense of gastropod feeding by spiders (Ecological Entomology 26). But that paper deals about bigger and even big spiders feeding on snails of adequate size, which is unlike the size relations in my observed case.

It is not trivial for a spider to incorporate anything from snail mucus, as this very sticky slime acts besides other functions as defense mechanism for the gastropod. In that context the above mentioned authors cite Tretzel (1961) by mentioning that mucus production of gastropods seems to have no deterring effect on some spiders. The question then is the efficiency of spider enzymes against snail tissue, a topic, about which I did not do more literature research. According to the above mentioned authors, moisture can in malacophagous spiders be an important factor, as gastropod bodies consist to a high percentage of water. They refer to Lain (1982), who published about New Zealand mygalomorph spiders. In the case of my observation it would eventually be of interest, referring to the context above, that also gastropod mucus contains a high water percentage. More observations such as mine would be needed to find out, whether the behavior of the linyphiid spider on a much bigger slug is a specific behavior or not.

Berlin, May-November 2020, urban park Rehberge, copyrights Stefan F. Wirth

Wild bee Andrena flavipes and nesting behaviors

The bee Andrena flavipes is also known as the common sand bee, as this species represents the most common of several regularly present sand bee species in Central Europe.

 

Aggregations at suitable nesting sites

 

Bee females create solitary nests, which is unlike to social hymenopterans such as the honey bee Apis mellifera. However huge and from a distance well visible aggregations of nesting A. flavipes specimens can appear. It is said that these aggregations are due to mated females being attracted to similar suitable nesting sites. In fact also a tolerance for conspecifics very close by is required to allow conditions, in which the whole ground seems to consist of bees, flying around and preparing their nests or importing pollen or nectar to feed their larvae. By the way: One nest contains contains about 2-3 brood cells only.

 

Specific conditions, in which specimens of my footage were found

 

The bees of my video were filmed between 4-6 April 2020 in the urban park around lake Plötzensee in Berlin. The site for my recordings was an area with forest edge character, interrupted by dry meadows, all at least in the afternoon exposed by the sun (temperatures between 15-20 °C).

 

 

Females of Andrena flavipes cleaning their nests, youtube: copyrights Stefan F. Wirth, April 2020

 

 

Orientation and nest cleaning behaviors of A. flavipes females, hindlegs as multifunctional organs

 

Contents of my behavioral documentation is the cleaning of nest hole entrance areas and behavior patterns, which seemingly support the orientation and finding their own nests again in midst of a sandy forest ground covered by fallen leaves.

To be enabled to recognize the entrance of the own nest again, bees perform regularly smaller walking tours around their nests to memorize soil structure and other details, being suitable to characterize this specific nesting site.

The bee’s hindlegs represent important multi-functional organs. They walk on them, collect pollen, which adhere to specific structures on legs III, and they are used to clean the areas in front of the nest openings from dirt, such as smaller stones or wooden particles. As nest entrance areas stay opened during the day, a proper cleaning of the soil around is regularly necessary. The bee performs that work mostly while backward-walking using its hindlegs like shovels to sweep dirt some centimeters away. This behavior is well visible in my footage.

 

General and short  information about mite associations

 

Andrena flavipes and other soil breeding wild bees are generally also of acarological interest. As presumably all hymenopterans, they have for example associations with phoretic mites, for example mites of the Scutacaridae (such as Imparipes apicola). I so far did not study mites on these bees, but phoresy means that mite instars use the insect as carrier to reach their final sites, in which they develop and reproduce. In case of Imparipes, adults feed on fungi and waste inside the bees brood cells.

 

 

Copyrights Stefan F. Wirth, Berlin april 2020, as always: all rights reserved