letting nature back in

The Kgalagadi desert’s butterflies featured in this post resonate with two posts from last year reflecting on resilience and fragility (symbolised by desert flowers) and the need for hope (symbolised by butterflies). It is just over a year since South Africa recorded its first confirmed case of Covid-19 and those posts were in response to the burgeoning uncertainty and fear as the pandemic’s inexorable infection rates escalated across the world.

Globally, locally and individually over the past year or so we have been through times that revealed our resilience and our fragility, and despite – or perhaps because of – all we have been through, we continue to lean towards hope where we can find it.

Desert butterflies exemplify a complex relationship between strength and vulnerability and the ability to survive in challenging circumstances.

Who would think that in the aridity of the Kalahari there could be such a proliferation of butterflies?

Strictly speaking the so-called Kgalagadi Desert is not truly a desert and is more accurately classed as semi-desert. Even though arid with no surface water, the rainfall and the density of the ground cover exceed the normal criteria for a desert (1992a Larsen: 182). Generally the vegetation cover is too extensive for new dunes to form.

Typical of such arid regions, temperature variations – both daily and seasonal – can be extreme in the Kgalagadi region, which straddles part of the borders between South Africa and Botswana and the eastern part of Namibia. In winter there can be severe frosts with temperatures as low as -15°C (5°F) and it is not unusual for summer daytime temperatures to be well over 40°C (104°F). Of the 250 species of butterflies that occur in Botswana only 41 are found in the Kgalagadi region. Most butterfly species cannot cope with the low or erratic rainfall, and many of those that can cope with drought cannot survive frost.

Most of these photos were taken on visits to Mabuasehube on the Botswanan side of the Kgalagadi Transfrontier Park where the vegetation is largely arid tree and shrub savannah. There are several large salt pans surrounded or covered by open grassland. Some photos were taken at the Central Kalahari Game Reserve (CKGR), Botswana, which has similar vegetation with the addition of fossil river beds and the occurrence of ‘tree islands’. (Kalahari is an alternative spelling of Kgalagadi, which literally means ‘thirstland’.)

Here Pioneer Caper Whites that are also commonly referred to as Brown-veined Whites (Belenois aurota) and African Migrant (Catopsilia florella) butterflies practically jostle at a mud-puddle

In the Kgalagadi butterflies are known to congregate at mud puddles not only to drink in hot weather but also to suck up minerals and salts available to them in the moist patches. These moist patches can be caused by splashing along the edge of waterholes, by puddles formed by urine (courtesy of animals and even visiting tourists) or, as in the photo above, by water discarded after rinsing off our breakfast mugs and dishes.

Although the Pioneer Caper Whites/Brown-veined Whites and the African Migrant butterflies predominate at many of the mud puddles we also saw Broad-bordered Grass Yellow (Eurema brigitta brigitta) and Common Orange Tip (Colotis evenina evenina) butterflies – these at the Central Kalahari Game Reserve (CKGR). On the right is a tiny butterfly in flight – one of the ‘Blues’

A Broad-bordered Grass Yellow (showing the broad black borders on its upper wings) can be seen flitting fast over a mud muddle where Pioneer Caper Whites/Brown-veined Whites, Orange Tips and African Migrants are taking advantage of the moisture

Less frequently at the mud puddles we saw the very striking Yellow Pansy (Junonia hierta cebrene) butterflies although they are a common species in the region. They occur also more widely across the drier parts of sub-Saharan Africa and on the Arabian Peninsula

Another delightful assembly of butterflies (and a few flies) at a mud puddle. At this spot we saw Pioneer Caper Whites/Brown-veined Whites, African Migrants, Broad-bordered Grass Yellows, Common Orange Tip butterflies and two species of the ‘Blues’ can be seen in the foreground

Several of the butterfly species that occur in the Kgalagadi region have migratory habits but the best known migrants are the Pioneer Caper Whites/Brown-veined Whites and the African Migrants because of massive migrations of these species that take place every so often, the most recent being the migration of Brown-veined Whites in January 2020. Rather than true migrations (as they don’t return) these mass movements of butterflies are more accurately described as dispersing (or emigrating) butterflies. Thousands and thousands of butterflies leave the Kalahari region and travel consistently in a north-easterly direction stopping in adverse weather conditions and to rest and feed as they go, with the females depositing eggs on larval host plants.

Larsen describes a massive migration of mostly African Migrant butterflies from Botswana in 1991. It was estimated that 1.5 billion individuals took part in this migration event. Interestingly he describes differences in morphology and behaviour of migrating compared to non-migrating individuals. For example, most migrating females were white morphs, looking more like typical males, than the yellow form that is more typical for females (1992b Larsen: 5).

African Migrant (Catopsilia florella) butterflies at a damp patch of sand in Mabuasehube Game Reserve. The yellow is the typical colouration for the female and the white with a greenish hue is the typical coloration of the male

Larsen refers to a previous massive migration in 1966 when African Migrants were predominant, although smaller numbers of Pioneer Caper Whites/Brown-veined Whites and African Monarchs (Danaus chrysippus) were also reported.

In the 1991 migration he mentions “modest numbers” of fellow travellers, including Common Diadem (Hypolimnas misippus), African Monarch (Danaus chrysippus), Pioneer Caper Whites/Brown-veined Whites (Belenois aurota), Yellow Pansy (Junonia hierta), Broad-bordered Grass Yellow (Eurema brigitta) and Spotted Joker (Byblia ilithyia) in varying proportions of the total number.

An African Monarch (Danaus chrysippus) feeding from the purple flowers of the Cat’s Tails (Hermbstaedtia fleckii) that brightens up the grasslands at Mabuasehube in the late summer

African Monarchs mud-puddling at Mabuasehube. This species (Danaus chrysippus), also known as Plain Tigers, has a wide range that includes most of Africa, much of Asia including India and it also occurs in parts of Australia and parts of southern Europe. It is distinct from the monarch species (Danaus plexippus) that occurs in North America

It is thought that the migrations of butterflies from the Kalahari take place most years but the explosion of vast numbers of butterflies occurs following good rains after a long period of drought. The African Migrants main larval host plant is a species of cassia a wild senna (Senna italica), a yellow-flowered ground creeper, which does exceptionally well after rains to the potential benefit of African Migrant caterpillars.

Commonly known in South Africa as Brown-veined Whites the Belenois aurota species, elsewhere more generally known as the Pioneer Caper White, occurs across most of Africa, the Arabian Peninsula and into Southern Asia and India

The exceptionally large migration of mainly Brown-veined Whites across southern Africa in January 2020 attracted a lot of attention including in the media. It is thought to have been the largest migration since 1966. The Kgalagadi Butterfly Migration originates in the dry Kgalagadi region and in parts of the northern Karoo. However, local butterflies on the migration route will join in the migration as it passes by. The butterflies migrate over several weeks to the wetter north-easterly regions crossing the breadth of southern Africa eventually reaching Mozambique in the east. Millions of butterflies crossing the country is a spectacular sight and their enormous numbers even grace highly urbanised areas including Johannesburg.

The larval host plant for the Pioneer Caper White/Brown-veined White butterflies in the Kgalagadi region is the Shepherd’s Tree (Boscia Albitrunca), a member of the Caper family. This photo was taken in the CKGR, Botswana. As the larvae (caterpillars) eat only indigenous plants in the Caper family, migrating butterflies do not pose a threat to crop plants. Migrating Brown-veined White butterflies lay their eggs only on plants in the Caper family

The Spotted Joker (Byblia ilithyia) has been observed taking a modest part in the migrations of the African Migrant butterflies. In the photo above two small butterflies in the ‘Blues’ family can be seen to the right of the colourful Spotted Joker with its wings spread in the early morning sunlight at the CKGR, Botswana

Although they are small, many blues species are migrants. Although I hesitate to make a pronouncement, I wonder whether this individual photographed at the CKGR is a Pea Blue (Lampides boeticus), which is a migratory species sometimes seen in the region

The Painted Lady (Vanessa cardui cardui) is a well-known cosmopolitan species of butterfly with a wide distribution, including in Mabuasehube, Botswana. This one I photographed sucking up moisture and minerals in a damp spot at the edge of a camp fireplace

I photographed this Pioneer Caper White/Brown-veined White butterfly feeding from a plant next to our secluded campsite on the edge of the Lesholoago Pan at Mabuasehube. The only other campsite at Lesholoago is on the other side of the pan

This African Monarch also favours feeding from this species of flowering plant. I have not been able to identify the plant, which is a fairly low-growing herb, and I would be grateful for any assistance in identifying it

Back lit by the setting sun a yellow female African Migrant butterfly takes nectar from a gazania flower at the CKGR

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Sources

Larsen, T.B. 1992a. The butterflies of the Gemsbok National Park in Botswana (Lepidoptera Rhopalocera). Botswana Notes and Records 24:181–204 https://journals.co.za/doi/pdf/10.10520/AJA052550590_278 ; Larsen, T. B. 1992b. Migration of Catopsilia florella in Botswana (Lepidoptera:Pieridae).Tropical Lepidoptera, 3:2-11. https://www.academia.edu/1770650/A_Migration_of_Catopsilia_Florella; Terblanche, RF. 2020. Current waves of butterfly migration over southern Africa. 30 January. Statement for LepSoc Africa. https://cdn.24.co.za/files/Cms/General/d/9912/967aed4d7e114b4ca28f65cf7c06573c.pdf; Woodhall, Steve. 2013. Pocket Guide Butterflies of South Africa. Cape Town: Struik Nature.

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Posted by Carol