The Landwalker

Sagittarius serpentarius: taken at Serengeti National Park, Tanzania.
(User:Yoki, 2008)

All birds of prey fly, with no exception. However there is one bird who walks and stomps the grasslands of Africa, the secretarybird (Sagittarius serpentarius) – The snake archer (just a damn cool name). Unlike other birds of prey, S.serpentarius likes to spend most of its time on the ground, preferring to walk rather than run and run rather than fly (Ferguson-Lees and Christie, 2001). Although more terrestrial in nature, S.serpentarius builds their nests in low trees and are monogamous (having a single mate for life) (Ferguson-Lees and Christie, 2001, Hofmeyr et al., 2014).

The secretarybird occupies quite a large range, covering much of sub-Saharan Africa, when they aren’t breeding they tend to be nomadic and are relatively rare to spot. Aside from being nomadic and monogamous, they are also territorial and roosts and builds nests on trees in their territory (Kemp, 1995, Hofmeyr et al., 2014). S.serpentarius shows some interesting behaviours, in flight they they may perform dives at each other, showing their claws at each other; sky dances, which is characteristic of accipitriforme eagles and hawks. Meanwhile, on the ground they chase each other around with wings raised much like cranes and storks (Ferguson-Lees and Christie, 2001).

The last two points should give you a hint to where I’m going with this, yes phylogeny!!! Being part of a monotypic family and genus: Sagittariidae and Sagittarius (that is, there’s only one genus in the family and only one species in the genus), they are considered quite unique. But just how unique are they in terms of phylogeny? Well it turns out there’s still a lot of debate regarding where secretarybirds lie in terms of phylogeny, although it is accepted with genetic testing that they are closer to eagles and hawks (Accipitridae) and ospreys (Pandioniae) than to falcons and storks and cranes, putting them under the order of Accipitriformes (Mahmood et al., 2014).

Fig. 1 Phylogram of families retrieved by matching genes, species marked with star used genome which are reported in the study which this is taken from. Values for bootstrap and pp values are shown at the nodes, * equaling to 100% bootstrap and 1.0 pp value, - equaling less than 60% bootstrap and lower than 0.9 pp value. Nodes where bootstrap and pp are both less than 60% are not shown (Mahmood et al., 2014).

Sagittarius serpentarius flying overhead at
 Tsavo East National Park, Kenya.
(User: putneymark, 2007)

S.serpertarius are listed as vulnerable and have seen a decline in population in recent years, owing to a number of threats including habitat encroachment, afforestation, disturbance of breeding, grazing of livestock removing habitat and being captured or killed by humans (Birdlife International, 2013, Ferguson-Lees and Christie, 2001, Hofmeyr et al., 2014). If we are to keep this archer of snakes around we must plan our developments and stop the habitat degradation and encroachment or it looks like their population will continue to decline.

BIRDLIFE INTERNATIONAL 2013. Sagittarius serpentarius. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 05 April 2015.

FERGUSON-LEES, J. & CHRISTIE, D. A. 2001. Raptors of the world, Houghton Mifflin Harcourt.

HOFMEYR, S. D., SYMES, C. T. & UNDERHILL, L. G. 2014. Secretarybird Sagittarius serpentarius Population Trends and Ecology: Insights from South African Citizen Science Data. PLoS One, 9.

KEMP, A. C. 1995. ASPECTS OF THE BREEDING BIOLOGY AND BEHAVIOUR OF THE SECRETARYBIRD SAGITTARIUS SERPENTARIUS NEAR PRETORIA, SOUTH AFRICA. Ostrich, 66, 61-68.

MAHMOOD, M. T., MCLENACHAN, P. A., GIBB, G. C. & PENNY, D. 2014. Phylogenetic position of avian nocturnal and diurnal raptors. Genome biology and evolution, 6, 326-332.

USER: PUTNEYMARK 2007. secretary bird Tsavo East feb 2007. Available: http://en.wikipedia.org/wiki/Secretarybird#/media/File:Sagittarius_serpentarius_-Tsavo_East_National_Park,_Kenya_-flying-8.jpg; Retrieved 05/04/2015

USER: YOKI 2008. Secretary Bird (Sagittarius serpentarius). Available: http://en.wikipedia.org/wiki/Secretarybird#/media/File:Sagittarius_serpentarius_Sekret%C3%A4r.JPG; Retrieved 05/04/2015