Why studying African birds’ varied migration patterns is so important

A white-throated swallow, one of several intra-African migratory birds. Photo credit: MartinMaritz/Shutterstock


Les Underhill recently published this piece in The Conversation (the original article can be found here).

Les Underhill, University of Cape Town


Bird migration comes in many flavours – and, as with ice cream, “vanilla” is the one people are most familiar with.

This is the process of flying from the northern hemisphere to the southern hemisphere, leaving the northern autumn and entering the southern spring; then making the return journey from autumn to spring. That sounds like a lifestyle to be envied: perpetual summer. But it’s not easily achieved. Birds must make the trip of thousands of kilometres using their energy and muscles; they have to deal with headwinds and storms.

Each year on the second weekend of May scientists, conservationists and bird lovers mark World Migratory Bird Day. In 2018, there’s a change to the calendar: the event will be marked twice, now also on the second Saturday in October. The organisers hope this will draw attention to migratory bird habits beyond the more studied and better resourced northern hemisphere.

This is an important step in recognising that there are hundreds of variations on the basic “flavour” of migration. Judging from attendance at international conferences, about three-quarters of ornithologists live and do research in the areas which were under the ice sheets of Europe and North America tens of thousands of years ago. So birds’ search for perpetual summer is what’s been most intensely studied.

Our knowledge of migration between Europe and Africa, and between North and South America, then, is good – but nowhere near complete. In an era of global climate change and development, scientists have realised that this knowledge is not static. It’s dynamic, and constantly shifting. The weak link in understanding vanilla migration is a knowledge of where each species spends the non-breeding season at the southern end of migration.

Vanilla migrants

Most bird species have been around for a long time, and have been through many ice ages. The most recent, known as the Pleistocene Epoch, ended around 12 000 years ago.

At the worst of this epoch – about 20 000 years ago – most of Europe north of about Spain and Italy was so cold and miserable that it was uninhabitable by birds throughout the year. Then gradually Europe’s climate became better for birds, but only in spring and summer.

It was precisely this strong seasonality which made the new territory so attractive. For most bird species, breeding occurs when there is a spike in food abundance. In the new territory, the thaw in spring was accompanied by a burst in plant growth. This was quickly followed by an abundance of caterpillars and other insects to feed on the plants, and to provide a reliable source of food for nestlings.

So as the permanent ice sheets across Europe and elsewhere retreated, the areas left behind became attractive breeding places. Once they’d bred, birds would escape to warmer places further south. The pattern that is recognised so well today was established.

But what about other forms of bird migration?

Different patterns

There are many species that migrate within the continent of Africa, appropriately known as “intra-African migrants”.

For instance, there are species which breed in South Africa in the southern summer and then head north, to elsewhere on the continent, in winter. Most swallows are in this category, notably the white-throated swallow. They leave in March-April, and are away until August-September. My fellow bird researchers and I think they migrate to countries farther north like Angola and Zambia.

Some birds fall into a second category: they are partial migrants. For example, about 80% of the Cattle Egrets in South Africa’s Gauteng province leave for warmer countries to the north each December and January. But there are always at least some Cattle Egrets throughout the province during winter. Partial migration is challenging even to recognise, because the species is continuously present throughout the year – and even harder to study.

Then there’s altitudinal migration. This is the idea that birds move downhill in winter to warmer places where there is more food. South Africa is one of the best places in the world to study altitudinal migration.

Tanya Scott, who recently completed her MSc with the Animal Demography Unit which I head at the University of Cape Town, was the first to comprehensively examine all the province’s bird species to identify altitudinal migrants. She searched for patterns that would help provide explanations for why some species undertake altitudinal migration, and others don’t. She found none. A week after her MSc was submitted, the first ever global review of altitudinal migration was published – and reached the same conclusions.

Altitudinal migration is a big puzzle. Vanilla migration is easy; all the birds do it. But developing an understanding of why some birds of a species migrate downhill after breeding and the birds in the neighbouring territory do not, is key to understanding how migration in a population starts.

There are many hypotheses about how long-distance migration started in species in which every individual migrates. These ideas can only be tested in the context of partial migration.

Understanding migration for conservation

The populations of many long-distance bird migrants are getting smaller. It is obvious that researchers can only develop effective conservation strategies for these species if we understand their spatial needs throughout their annual cycle.

The ConversationAnd many partial migrants are categorised as being “threatened” with extinction. Understanding the where, the when and the how of their movements is key to their protection. Mountains are particularly impacted by climate change, and a study of altitudinal migrants might well reveal that a disproportionate number of them are threatened.

Les Underhill, Professor, Biodiversity Informatics, University of Cape Town

This article was originally published on The Conversation. Read the original article.

Birds and barbed wire

Birds and barbed wire – by Les Underhill

Barbed wire was invented in America in the 1860s, and used to keep cattle inside of camps, or outside of crops.

Within a few decades, farmers in the old Cape Colony had found a new use for barbed wire. In 1892, a civil servant in the Colony’s Department of Agriculture designed a vermin-proof fence that utilized closely strung and interlaced strands of barbed wire. He reasoned that if this were widely adopted, it would make the extermination of jackals and other “vermin” much easier. The farmers lobbied the government, and they were even provided with financial assistance to build jackal-proof fencing. Within the first decades of the 1900s, the “Fencing Movement”, aided and abetted by Parliament through an assortment of “Fencing Acts”, had successfully transformed the natural landscapes of South Africa into a patchwork mosaic of fields and camps.

A century has passed, during which jackals and other vermin have remained as big a problem as they ever were. But the barbed wire fences remain. Some are carefully maintained and others have rotten to rust. But they have undoubted been the catalyst that, over the past century, has altered the way South Africa looks.

Barbed wire along roads takes us back to its original purpose: keeping animals inside the camps. Here, barbed wire fences are both the bird photographer’s curse and the photographer’s blessing. The barbed wire either gets in the way, or it provides a perch out in the open!

Photo credit: Les Underhill

This Southern Red Bishop is easy out on the fence line

Photo credit: Les Underhill

Take away the out-of-focus barbed wire, and this would be reasonable image of a Capped Wheatear

Photo credit: Les Underhill

These Red-eyed Doves are using the fence to soak up the early morning sun

Photo credit: Les Underhill

The fenceline and dropper are almost conspiring to hide the distinguishing feature of the Cape Longclaw

Photo credit: Les Underhill

Being flat-footed on the dropper is probably more comfortable than curled up feet on the wire for the Common Fiscal

Photo credit: Les Underhill

Cape Weaver hiding, unsuccessfully, behind the wire

Photo credit: Les Underhill

This Cape Bulbul has its right foot too close to the sharp end for comfort

Photo credit: Les Underhill

The Speckled Pigeon is too large to hide behind the wire

International Citizen Science Day in The Company’s Garden

Photo Credit: Les Underhill

International Citizen Science Day in The Company’s Garden – by Les Underhill

All but one of the thousands of people in The Company’s Garden, in the heart of Cape Town, were there to enjoy the autumn sun, and hoping for rain. I was there to celebrate International Citizen Science Day, Saturday, 14 April 2018. The sun made it easy to take photos for the Virtual Museum (http://vmus.adu.org.za).

Photo Credit: Les Underhill

The dragonflies and damselflies, taken together, are called the Odonata. The damselflies mostly fold their wings over their backs, but they are mainly associated with really clean freshwater. So it was a bit of a surprise to find a damselfly sitting on the stalks emerging from the ornamental pond in the top photo.

Photo Credit: Les Underhill

The pair of Egyptian Geese in this pond had one gosling. Probably this was the only one left of a brood; the average starting off size of a brood is eight. This brood shrinkage is not a conservation issue in The Company’s Gardens. There is no shortage of Egyptian Geese.

Photo Credit: Les Underhill

This goose parent used the fountain in the ornamental pond as lookout. Cecil John Rhodes, of Cape to Cairo ambitions, has turned his back on this Egyptian Goose. Reminders of the failure to put a railway from here to Egypt is apparently a stressful topic.

Photo Credit: Les Underhill

The war horses and soldiers of the Delville Wood Memorial have to withstand the unsavoury attentions of the Hartlaub’s Gulls. They provide a great vantage point from which they can swoop down on anyone who scatters any food.

Photo Credit: Les Underhill

The Company’s Garden has a well-maintained section of vegetables. This is the best spot for butterflies. The most abundant butterfly today was the Cabbage White. This is South Africa’s only invasive alien butterfly. It was first recorded in Sea Point, Cape Town, in 1996, and has already expanded its range as far as the Eastern Cape.

Photo Credit: Les Underhill

This African Monarch was still flying in spite of large fractions of its wing area having worn away.

Photo Credit: Les Underhill

Here is a younger and more vibrantly coloured African Monarch.

Photo Credit: Les Underhill

Outside of suburbia, the Garden Acraea, occurs mainly in forest and woodland. It has moved into the suburbs on a large scale, because its favourite host plant on which its caterpillars feed is the Wild Peach Kiggelaria Africana, and these are grown in many gardens.

Photo Credit: Les Underhill

Another species that originally was a forest inhabitant is the Hadeda. This noisy bird has made itself at home in the suburbs, and in The Company’s Garden it happily feeds in the beds while people walk by on the adjacent footpaths.

Photo Credit: Les Underhill

This Grey Squirrel is another introduced alien, which seems to have The Company’s Garden as the epicentre of its Cape Town distribution. Here is one, of hundreds, and it is feeding on an acorn, from an introduced oak tree. So far, there is nothing unusual about all of this.

Photo Credit: Les Underhill

But the squirrel moves off looking like a rabbit. Somehow, it is coping with life minus its bushy tail.

All these photographs will be uploaded to the Virtual Museum. They will be valuable in two ways. They will confirm the continued existence of each species in this locality. And especially for the butterflies, and for the damselfly, these records will provide information on the time of the year when they are in flight. As we move through April, and the weather in Cape Town gets cooler, we anticipate seeing fewer and fewer of these two groups of insects.

Paardeberg site report – 2018/04/07

By Les Underhill. Photo credits: Les Underhill and Dieter Oschadleus

Team BDI explored the northwest corner of the Paardeberg on Saturday 7 April 2018. We visited the part of this mountain range which is closest to Malmesbury. Technically, the Paardeberg is a series of granite plutons – dome-shaped hills. It was called the Paardeberg because, when discovered, it had been inhabited by quaggas, which to the early settlers were horselike. This is a fascinating area, and one we plan to revisit.

We joined an expedition led by Arnold van der Westhuizen to check two camera traps. Leopard scats had been reported here recently, and the cameras had been set up in the hope of confirming the presence of this seldom-seen animal. We found leopard scats and uploaded them to MammalMAP: http://vmus.adu.org.za/?vm=MammalMAP-24172

On the foothills of the Paardeberg, the main crop is grapes, but there was no water in the farm dams for irrigation this summer, and there was no harvest in the higher lying vineyards. Above the agricultural areas is a band of renosterveld. Go a little higher, and the proportion of plants which are proteas, ericas and restios increases, and renosterveld gives way to fynbos.

The camera traps had taken a total of 44 photos. All of them turned out to be baboons, and some were caught in some unusual poses! Maybe a leopard or two would help create a “landscape of fear” for the baboons.

Cape Black-Eye
Cape Black-Eye

At the end of long, dry, drought summer, biodiversity was scarce. This was one of only two butterflies we saw. It is a Cape Black-eye Leptomyrina lara (http://vmus.adu.org.za/?vm=LepiMAP-645342) This is a species that frequently rests on bare ground, and did so for us. The Cape Black-eye occurs mainly in the more arid western half of South Africa, in Lesotho and it also occurs northwards into Namibia. This is the sixth record of the species in the Paardeberg, and the others have also been within a few kilometres of this spot.

Crimson-speckled Footman

The Crimson Speckled Footman Utetheisa pulchella is a moth that flies in the daytime (http://vmus.adu.org.za/?vm=LepiMAP-645342). It looks like a white butterfly in flight; but when it is settled the red and black pattern on the white wings makes it instantly recognisable. These moths are unpalatable to birds; the bold wing colours serve as warning to predators: “I am toxic”, or, in technical terms, “I have a condition called aposematism.” The Crimson Speckled Footman has a wide distribution across Africa and southern Asia. The South African distribution map should show an almost continuous range.

We didn’t see any mammals, not even a baboon, but we did find this porcupine quill and submitted it to the MammalMAP section of the Virtual Museum (http://vmus.adu.org.za/?vm=MammalMAP-24182).

Two species scorpions were found. This one is Uroplectes carinatus (http://vmus.adu.org.za/?vm=ScorpionMAP-3161). The scorpions don’t yet have English “common” names, like the birds, butterflies and dragonflies do. The identity of the second species is still being debated by the specialists (http://vmus.adu.org.za/?vm=ScorpionMAP-3160).

We are grateful to Arnold van der Westhuizen for being our guide.

Lacewings at Little England, Beaufort West

Nesoleon boschimanus. Photo credit: Les Underhill (2018)

Report by Les Underhill

Lacewings are not one of the charismatic groups of insects, and have been poorly studied. They consume aphids and do pollination, so they are one of the key ecosystem service providers, and deserve better attention than what they have received to date. There is only one entomologist in South Africa who has focused on lacewings, Dr Mervyn Mansell, at the University of Pretoria. He says that, in South Africa, there are currently 415 described species in 14 families of lacewings. There are many taxa that await description, and he reckons that we should eventually end up with about 500–550 species for South Africa. For the whole of Africa, it is likely that there will prove to be 1000–1500 species.

On three trips to the Landmark Foundation’s farm at Little England in the Karoo north of Beaufort West a total of 18 lacewing have been photographed and uploaded to the LacewingMAP section of the Virtual Museum (http://vmus.adu.org.za). 13 have been identified to species level, three to genus and, for one, the photo was only good enough for the ID to be done to family. The number of species so far is a paltry six! But it is a start. These are the first ever records for this grid cell.

Mervyn Mansell, who does the identifications for LacewingMAP, reckons that we could expect at least 50 species in that area. “It is actually an extremely rich area for lacewings. Lots of fieldwork needs to be done here.”

The first six species for this grid cell are listed below. The species notes were written by Mervyn Mansell in his comments on the identification. The number of records to date is given, as well as the link to the record in LacewingMAP with what is currently the best available photo of the species in the grid cell. The distribution map for each species, based on the LacewingMAP database, is also provided. The take home message from these maps is plain: Our knowledge of the distributions of the lacewings is weak.

Systematic list of lacewings recorded on the farm Little England

Centroclisis maligna. Photo credit: Les Underhill (2018)

Centroclisis maligna (Myrmeleontidae)

This species is fairly common and widespread in the drier western parts of southern Africa. It is readily distinguished form other Centroclisis species by its reddish colour. The large robust three-toothed larvae live freely in sand and do not construct pitfall traps.

One record: http://vmus.adu.org.za/?vm=LacewingMAP-10704


Creoleon mortifer. Photo credit: Les Underhill (2018)

Creoleon mortifer (Myrmeleontidae)

A common and widespread species, occurring throughout most of southern Africa and northward. It is highly variable, often with black streaks in the wings that have led to numerous synonyms. Rests with wings wrapped around the body. Larvae live freely in sand.

Two records: http://vmus.adu.org.za/?vm=LacewingMAP-10758


Myrmeleon doralice. Photo credit: Les Underhill (2018)

Myrmeleon doralice (Myrmeleontidae)

This species is common and widespread throughout southern Africa, particularly in the drier areas. Larvae construct pits and are pinkish in colour. Although the adults are fairly common, the larvae are not frequently encountered, although they are pit builders, and usually occur in open exposed situations.

Three records: http://vmus.adu.org.za/?vm=LacewingMAP-10706 m


Nannoleon michaelseni. Photo credit: Les Underhill (2018)

Nannoleon michaelseni (Myrmeleontidae)

This species is widespread in South Africa and Namibia, and is fairly common in the drier western parts of the subregion. It is currently the only species in the genus, although another undescribed species is also known. It is characterized by the broad clear wings and long clavate antennae. Nothing is known of its biology.

Two records: http://vmus.adu.org.za/?vm=LacewingMAP-10701


Nesoleon boschimanus. Photo credit: Les Underhill (2018)

Nesoleon boschimanus (Myrmeleontidae)

This species is widespread in South Africa and Namibia, and is fairly common in the drier western parts of the subregion. It is currently the only species in the genus, although another undescribed species is also known. It is characterized by the broad clear wings and long clavate antennae. Nothing is known of its biology.

Three records: http://vmus.adu.org.za/?vm=LacewingMAP-10705


Dichochrysa tacta. Photo credit: Les Underhill (2018)

Dichochrysa tacta (Chrysopidae)

Another of the “brown” “green lacewings”. Fairly widespread and common in the drier western parts of South Africa. Not known from neighbouring countries. Larvae live freely on vegetation, where they are active predators.

Two records: http://vmus.adu.org.za/?vm=LacewingMAP-10784


We are grateful to the Landmark Foundation for their warm hospitality at Little England. Mervyn Mansell’s role in doing the identifications and writing the comments is crucial to the success of this project.

The data were extracted from the LacewingMAP section of the Virtual Museum (Animal Demography Unit (2018). LacewingMAP Virtual Museum. Accessed at http://vmus.adu.org.za/?vm=LacewingMAP on 2018-04-02)


Bird ringing report – Paardeberg 28 March 2018

Cape Robin-chat Cossypha caffra. Photo credit: Dieter Oschadleus (2018)

Cape Robin-chat – Virtual Museum record

Report by Dieter Oschadleus on our first BDI bird ringing in the Paardeberg.

The Paardeberg stands out as a mountainous island in an agricultural landscape between Paarl/Wellington and Malmesbury in the Swartland region of the Western Cape. Very little bird ringing has taken place here, so Les Underhill and I had a bird ringing session in the Paardeberg, on Bowwood Farm, on Wednesday, 28 March 2018.

The top species was Cape White-eye (n=22), followed by Southern Masked Weavers (n=8), of which two were males in partial breeding plumage. The ring of one bird has been recovered in the Paardeberg area, a Cape Weaver ringed with ring 231054 in Tygerberg.

Thanks to Julian and Bridget Johnsen for hosting us! We hope to do a lot more bird ringing in the Paardeberg.

Streaky-headed Seedeater Serinus gularis. Photo credit: Dieter Oschadleus (2018)

Streaky-headed Seedeater – Virtual Museum record

Karoo Prinia Prinia maculosa. Photo credit: Dieter Oschadleus (2018)

Karoo Prinia – Virtual Museum record

Cape Weaver Ploceus capensis. Photo credit: Dieter Oschadleus (2018)

Cape Weaver – Virtual Museum record

Southern Masked-weaver Ploceus velatus. Photo credit: Dieter Oschadleus (2018)

Southern masked-weaver – Virtual Museum record

Olive Thrush Turdus olivaceus. Photo credit: Dieter Oschadleus (2018)

Olive Thrush – Virtual Museum record

Cape White-eye Zosterops virens. Photo credit: Dieter Oschadleus (2018)

Cape White-eye – Virtual Museum record