Species models

Skylark

Alauda arvensis is a common and charismatic species of agricultural landscapes.

Sources: - Bauer, H.-G., Bezzel, E., & Fiedler, W. (Eds.). (2012). Das Kompendium der Vögel Mitteleuropas: Ein umfassendes Handbuch zu Biologie, Gefährdung und Schutz (Einbändige Sonderausg. der 2., vollständig überarb. und erw. Aufl. 2005). AULA-Verlag - Delius, J. D. (1965). A Population Study of Skylarks Alauda Arvensis. Ibis, 107(4), 466–492. https://doi.org/10.1111/j.1474-919X.1965.tb07332.x - Donald et al. (2002). Survival rates, causes of failure and productivity of Skylark Alauda arvensis nests on lowland farmland. Ibis, 144(4), 652–664. https://doi.org/10.1046/j.1474-919X.2002.00101.x - Glutz von Blotzheim, Urs N. (Ed.). (1985). Handbuch der Vögel Mitteleuropas. Bd. 10. Passeriformes (Teil 1) 1. Alaudidae - Hirundidae. AULA-Verlag, Wiesbaden. ISBN 3-89104-019-9 - Jenny, M. (1990). Territorialität und Brutbiologie der Feldlerche Alauda arvensis in einer intensiv genutzten Agrarlandschaft. Journal für Ornithologie, 131(3), 241–265. https://doi.org/10.1007/BF01640998 - Püttmanns et al. (2022). Habitat use and foraging parameters of breeding Skylarks indicate no seasonal decrease in food availability in heterogeneous farmland. Ecology and Evolution, 12(1), e8461. https://doi.org/10.1002/ece3.8461

Initialise the skylark population. Creates pairs of skylarks on grassland and agricultural land, keeping a distance of 60m to vertical structures and giving each pair an area of 3ha.

allowsnesting(skylark, model, pos)

Check whether the given position is suitable for nesting.

Females that have laid eggs take care of their chicks, restarting the nesting process once the chicks are independent or in case of brood loss.

Initialise a skylark individual. Selects migration dates and checks if the bird should currently be on migration. Also sets other individual-specific variables.

destroynest!(skylark, model, reason)

Remove the skylark's nest and offspring due to disturbance or predation.

findterritory(skylark, model)

Check whether the habitat surrounding the skylark is suitable for establishing a territory. If it is, return the list of coordinates that make up the new territory, else return an empty list.

foragequality(skylark, model, pos)

Calculate the relative quality of the habitat at this position for foraging. This assumes that open habitat is best (quality = 1.0), and steadily decreases as vegetation height and/or cover increase. (Linear regressions based on Püttmanns et al., 2021; Jeromin, 2002; Jenny, 1990b.)

Females returning from migration move around to look for a suitable partner with a territory.

Females that have found a partner build a nest and lay eggs in a suitable location.

Non-breeding adults move around with other individuals and check for migration.

Once a male has found a territory, he remains in it until the breeding season is over, adjusting it to new conditions when and as necessary.

Males returning from migration move around to look for suitable habitats to establish a territory.

Marbled White

Melanargia galathea is a grassland specialist butterfly.

Sources: - Baguette et al. (2000). Population spatial structure and migration of three butterfly species within the same habitat network: Consequences for conservation. Journal of Applied Ecology, 37(1), 100–108. https://doi.org/10.1046/j.1365-2664.2000.00478.x - Dennis (Ed.). (1992). The ecology of butterflies in Britain. Oxford University Press. - Ebert & Rennwald (1991). Die Schmetterlinge Baden-Württembergs, Bd.2, Tagfalter: Satyridae, Libytheidae, Lycaenidae, Hesperiidae. Verlag Eugen Ulmer. - Evans et al. (2019). Integrating the influence of weather into mechanistic models of butterfly movement. Movement Ecology, 7(1), 24. https://doi.org/10.1186/s40462-019-0171-7 - Gotthard et al. (2007). What Keeps Insects Small? Time Limitation during Oviposition Reduces the Fecundity Benefit of Female Size in a Butterfly. The American Naturalist, 169(6), 768–779. https://doi.org/10.1086/516651 - Hannappel & Fischer (2020). Grassland intensification strongly reduces butterfly diversity in the Westerwald mountain range, Germany. Journal of Insect Conservation, 24(2), 279–285. https://doi.org/10.1007/s10841-019-00195-1 - Lenda & Skórka (2010). Patch occupancy, number of individuals and population density of the Marbled White in a changing agricultural landscape. Acta Oecologica, 36(5), 497–506. https://doi.org/10.1016/j.actao.2010.07.002 - Reinhardt et al. (2007): Tagfalter von Sachsen. In: Klausnitzer & Reinhardt (Hrsg.) Beiträge zur Insektenfauna Sachsens Band 6. – Entomologische Nachrichten und Berichte, Beiheft 11, 696 + 48 Seiten. Dresden. - Roy et al. (2001). Butterfly numbers and weather: Predicting historical trends in abundance and the future effects of climate change. Journal of Animal Ecology, 70(2), 201–217. https://doi.org/10.1111/j.1365-2656.2001.00480.x - Schulte et al. (2007). Die Tagfalter der Pfalz—Band 2. Gesellschaft für Naturschutz und Ornithologie Rheinland-Pfalz. - Vandewoestijne et al. (2004). Dispersal, landscape occupancy and population structure in the butterfly Melanargia galathea. Basic and Applied Ecology, 5(6), 581–591. https://doi.org/10.1016/j.baae.2004.07.004

Initialise the marbled white population with one individual on every grassland pixel.

Adult marbled whites (we only simulate females) fly around more or less randomly on days with good weather, laying eggs on suitable habitat.

Movement

Adults move a given number of steps each day, depending on the temperature (see below). Each step, an individual scans its surroundings in concentric circles, looking for the closest spot that offers suitable habitat which it hasn't visited today. (Depending on the habitatpreference and selfavoidance parameters, spots that are not suitable habitat or have been visited before may also be selected.) Spots with higher population densities are more likely to be avoided (avoidance increases linearly up to 100% at maxindperpixel). If no suitable spot is found, the individual moves to a random location on the periphery of its vision. After each step, if it is in a suitable habitat, the individual lays an egg, up to maxeggsperday (depending on temperature, see below).

Temperature

Temperature affects both the distance moved and the number of eggs laid each day. The optimal temperature is taken to be the midway point between the species' minimum and maximum temperatures (i.e. 24°C). Outside the species' temperature range (18-30°C), neither movement nor oviposition take place. Within that range, the number of steps each day peaks at the optimum temperature and declines linearly on either side of it. (cf. Evans et al., 2019). The number of eggs laid declines linearly if the temperature is below the optimum, but stays stable above it (cf. Gotthard et al., 2007). The daily mean temperatures are used as the basis for calculation (using the maximum temperature produces wrong model results during heat waves).

Initialise a marbled white individual. Mainly defines the time this individual will spend in each phase. (This ought to be temperature-dependent rather than random, but I don't have data for that.)

Juvenile individuals (i.e. eggs, larvae, pupae) simply wait for the eclosing day.

Juvenile individuals (i.e. eggs, larvae, pupae) simply wait for the eclosing day.

moveproximity(self, model)

Each step, an individual scans its surroundings in concentric circles, looking for the closest spot that offers suitable habitat which it hasn't visited today. (Depending on the habitatpreference and selfavoidance parameters, spots that are not suitable habitat or have been visited before may also be selected.) Spots with higher population densities are more likely to be avoided (avoidance increases linearly up to 100% at maxindperpixel). Returns nothing if no suitable spot is selected.

moverandom(self, model)

The butterfly randomly inspects pixels within its field of view and moves to the first suitable spot it finds. Depending on the habitatpreference parameter, spots that are not suitable habitat may also be selected. Spots with higher population densities are more likely to be avoided (avoidance increases linearly up to 100% at maxindperpixel). Returns nothing if no suitable spot is selected.

Juvenile individuals (i.e. eggs, larvae, pupae) simply wait for the eclosing day.

recordlifestats(butterfly, model)

Save this butterfly's life stats to file.

recordmovementstats(butterfly, model)

Record the habitat category of the butterfly's current location in its life stats.

suitablehabitat(butterfly, model, pos)

Check whether the given position is suitable for oviposition. This means: the land cover must be either grass or fallow, and if grass, must either not be managed, or not have been fertilised and be a certain height.