by Derek Engelbrecht
African parids (tits) are relatively poorly known compared to their northern hemisphere relatives. Most of our knowledge of this fascinating group of birds in Africa stems from studies on Southern Black Tit by Tarbot- on (1981), Ashy and Carp’s Tit by Wiggins (2001) and Stripe-breasted Tit by Shaw (2003). Wiggins (2001) studied aspects of Ashy Tit breeding in Namibia, e.g., breeding phenology, clutch size, incubation and brooding behaviour, and nestling provisioning rates. Here I report on the growth and development of Ashy Tit nestlings but also share some incidental observa- tions made during data collection at seven nests in the Polokwane Game Reserve between 2003 and 2017.
Laying dates
Egg-laying started in November at five of the nests, laying at one nest only starting on the 4th January 2004. This is unusually late for the species as Tarboton (2011) lists South Africa’s laying dates as October and November. Although I found no evidence of repeat-brooding attempts, this record may have been a replacement-brooding attempt. Indirect evidence of a replacement-brooding attempt was found at a nest lost between 15 and 18 November 2003. The male was seen inspecting nest holes on the 20th November 2003 by hovering in front of cavities and cautiously peeping in.
Breeding system
According to Dean (1989), Ashy Tit may be a facultative cooperative breeder in parts of its range, e.g., the Northern Cape region. However, no evidence of such a breeding strategy was observed by Wiggins (2001) in Namibia, nor was it observed at my study site in the Central Limpopo Province.
Nest site
Three of the seven nesting attempts in this study were in nest boxes. The remaining three were in previously excavated cavities (barbets or wood-peckers), all in Mountain Aloe Aloe marlothii. The lowest and highest natural nests were 1.1 m and 1.95 m above ground level. The artificial nest boxes included a sisal log, a commercial nesting log as used for small par- rots, and a nest constructed of a plastic pipe.
Nest preparation and nest material used
Only the female was seen carrying nesting material, but she was closely followed by her partner during nest construction. The bulk of the nesting material comprises animal hair. Other materials recorded included bits of a plastic sachet, a few soft grass culms, pieces of snakeskin (in 4 of 7nests), small feathers (rarely) and small amounts of plant material. The snake-skin may serve as a deterrent to a nest inspector as it is likely to be the first object an intruder might notice in the gloom of a cavity.
Interestingly, more often than not, the plant material used was rather aromatic, e.g., the leaves of the Lemon Bush Lippia javanica and Black Jack Bidens formosa. The use of aromatic plants by birds nesting in enclosed/ domed nests or cavities improves the health and survival of nestlings and fledglings (Milton and Dean 1999). The nest material forms a thick pad, about 5−8 cm deep in which a cup is formed. Known sources of hair for nest lining include recycling of nest material from a previous nesting attempt, sometimes even of another species – a kind of kleptoparasitism. I once found an Ashy Tit leaving a Red- billed Oxpecker nest (the oxpeckers had completed their breeding) with a beak full of fur. This would be an easy source of hair as oxpeckers collect nesting material directly from their hosts! Another known source of hair is regurgitated vulture pellets (Dean 2005). Although no vultures nest in the Polokwane Game Reserve, Secretary- bird, a few raptors, and a host of small carnivores are resident within the reserve. Their pellets and faeces may be potential sources of nest lining.
Eggs and clutch size
In seven nests, the clutch size ranged from4(n=6)to5(n=1),mean=4.7 eggs. This is slightly more than the mean for South Africa (mean = 4, n = 6 nests) but similar to the average clutch size in Namibia (mean = 4.7, n = 21). The egg shape and colouration match the description of Tarboton (2011). The egg dimensions (min- mean-max) of 18 eggs were as follows: 17.4-18.59-19.7 x 13.9-14.35-15. The fresh egg mass (i.e., eggs weighed within three days of laying) of six eggs were 2.08 g ± 0.11, range (1.92−2.23 g).
Incubation
Females appeared to be solely respon- sible for incubation. Males occasion- ally provisioned the incubating fe- males. Full contact incubation started after the penultimate egg in a clutch was laid. The incubation period was reliably established at 13 and 15 days (n=2).
The female performs a distraction display similar to that described for Southern Black Tit (Tarboton 1981). I once peered into a natural nest in a Mountain Aloe using a penlight and dentist’s mirror. I had the fright of my life when the female hissed loudly and struck the sides of the nest with her wings, resembling a striking snake. Needless to say, I jumped backwards, thinking there was a snake in the nest. After I composed myself, I attempted to see what she did. I noticed that the female hisses and sways from side to side, resembling a snake. The wing-strike creates a rather loud drumming sound. She also lunged at the nest entrance with a beak full of the lining. The distraction display is remarkable for its resemblance to a striking snake and enough to deter any potential intruder – or curious ornithologist!
Development and care of nestlings
Nestling development is summarised in Table 1. The female will brood for 7−12 days, but he male provisions his mate as well as the nestlings. Both sexes provision the nestlings and assist with nest sanitation by removing faecal sacs. The nestling period ranged from 19−22 days, and the fledglings can fly well at fledging.
Breeding success
Of 29 eggs laid in the seven nests under observation, 13 eggs hatched (44.8%), and all 13 nestlings fledged, giving a crude breeding success rate of 45%. Known causes of nest failure included predation by an egg-eater snake (regurgitated eggshell found in the nest) and eviction by Cape Starling. The starling removed the eggs from the nest and dropped them outside.
Dean WRJ. 1989. Ashy Tit. In Ginn PJ, McIlleron WG, Milstein PleS (eds). The Complete Book of Southern African Birds. Cape Town: Struik/Winchester. p. 459.
Dean WRJ. 2005. Ashy Tit. In Hockey PAR, Dean WRJ, Ryan PG. (eds). Roberts birds of southern Africa. 7th Edn. Cape Town: The Trustees of the John Voelcker Bird Book Fund. p. 742.
Milton S, Dean WRJ. 1999. Nesting thyme. The use of aromatic plants in Cape Sparrow nests. Africa Birds and Birding 4(1): 37−39. Shaw P. 2003. Breeding activity and provisioning rates of Stripe-breasted Tits (Parus fasciiventer) at Bwindi Impenetrable Forest, Uganda. Ostrich 74: 129−132.