Random time-activity budgets in captive Southern Ground Hornbill Bucorvus leadbeateri

The conservation status of the Southern Ground Hornbill (Bucorvus leadbeateri) is vulnerable on the IUCN Red List.1 The Mabula Ground Hornbill Conservation Project (2011) and Southern Ground Hornbill conservation in general aim to increase the number of hornbills through five main techniques: (1) supplemental feeding, (2) double clutching, (3) alternation of chicks, (4) group augmentation and (5) chick fostering. Numbers are threatened directly by habitat loss, hunting and international trade, and indirectly by group size (through the Allee effect) and communal breeding.2-7 Furthermore, the species has a highly K-selected life-history pattern.8 Captive breeding of this bird can potentially increase the population size twofold because both eggs laid are guaranteed a chance of survival, whereas in the wild only one egg is likely to survive.


Introduction
The conservation status of the Southern Ground Hornbill leadbeateri is vulnerable on the IUCN Red List (Birdlife International, 2012).The Mabula Ground Hornbill Conservation P attempts to increase the number of hornbills by five main techniques supplement feeding, double clutching, alternation of chicks, group augmentation and chick fosters (Kemp, 2000).Numbers are threatened directly by habitat loss, hunting and international trade (Trail, 2007), and indirectly by reporting rates ( Herremans, 1997), group size (Hulley and Craig, communal breeding (del Hoyo et al. 2001; Tyler in litt.Furthermore, it has a highly K-selected life-history pattern (Kemp and Kemp, 1980).Captive breeding of this species can potentially increase the population size two-fold because both eggs laid are guaranteed survival.But when does mating occur?Time-activity budgets in birds can be used to illustrate reproductive effort (Brunton 1988).Time-activity budgets for Southern Ground Hornbills are only known from wild birds in the Kruger National Park (Kemp and Begg, 2001).Here we determine the time budgets of captive Southern Ground Hornbills in the Johannesburg Zoo and compare these with randomly expected captivity.

Results
Times for the scan observations totalled 26 hours.There was no significant difference between the observed behaviours and thos expected by chance (N=12, p=0.91) in Southern Ground Hornbill There were no significant differences between observed and expected male behaviours ( N =12, p=0.98), observed versus expected female behaviours (N=12, p=0.87) and observed versus expected juvenile behaviours (N=12, p=1.00).
Of the twelve behaviours recorded walking was always the most common (51%), followed by standing (18%), foraging (8%), perching (7%) and sitting (5%).Less commonly observed behaviours included preening (2%), flying (1%), and running (1%).Communication in the form of bill interactions and territorial calling was recorded in 4.5% of the observations.The female called more frequently (4.1%) than the male (3.3%).The female spent more time perched than the male or the juvenile.The juvenile spent more time foraging and less time walking than either of the adults.

Discussion
The captive Southern Ground Hornbill time-activities observed were no different from randomness (Table 1).In other words, no significant -ISSN 2219-0341 -(ix) flying, (x) observed data were and converted into percentiles.Random expected frequencies were generated by dividing the observed frequencies by the number of (behavioural) categories to get the expected frequencies (Zar 1989).The observed ere compared using the CHITEST tatistical function in MS Excel ( 2007); which generated probability-There was no significant difference between the observed behaviours and those Southern Ground Hornbills.differences between observed and =0.98), observed versus =0.87) and observed versus Of the twelve behaviours recorded walking was always the most common (51%), followed by standing (18%), foraging (8%), perching (7%) and sitting (5%).Less commonly observed behaviours included %), and running (1%).Communication in the form of bill interactions and territorial calling was recorded in 4.5% of the observations.The female called more frequently (4.1%) than the male (3.3%).The female spent more time perched than the male or venile.The juvenile spent more time foraging and less time activities observed were no different from randomness (Table 1).In other words, no significant differences between the 12 behaviours observed in the three birds and those expected by chance were found.The possible exception to randomness is the higher frequency of female vocalization.a species-specific behaviour and is known as territorial calling ( and Kemp, 1980).The higher frequencies of territorial calling by the female may be female control (Eberhard, 1996).Preening, foraging, and sitting appeared less frequently than the same behaviour observed in wild birds (Kemp and Captive birds may be less prone to parasitism than wild birds?Foraging pressures may be released in captivity be provided in compact spatio-temporal instances and hence it occupies less time-activity.The juvenile may be spending and less time walking because this is optimal for a helper in a captive environment analogous to the power struggles in cooperative breeders (Koenig 1981).The higher frequency of female s between the 12 behaviours observed in the three birds and those expected by chance were found.The possible exception to randomness is the higher frequency of female vocalization.This is specific behaviour and is known as territorial calling (Kemp and Kemp, 1980).The higher frequencies of territorial calling by the female may be female control (Eberhard, 1996).Preening, foraging, and sitting appeared less frequently than the r observed in wild birds (Kemp and Begg, 2001).Captive birds may be less prone to parasitism than wild birds?Foraging pressures may be released in captivity because food is temporal instances and hence it occupies ing more time foraging and less time walking because this is optimal for a helper-at-the nest to the power struggles in cooperative breeders (Koenig 1981).The higher frequency of female perching indicates defence of the nest site (Rendell and Robertson, 1994).
A future study could directly compare these data with Begg (2001) using a contingency table.

Conclusions
The time-activity budgets of captive breeding Southern Ground Hornbills indicated random behaviour with the exception of vocalizations which were more frequent in the female compared to the male.

Fig 1 -
Fig 1 -Male Southern Ground Hornbill in Kruger National Park Courtesy: Trevor Hardaker

Table 1 :
Time-activity budgets of Southern Ground Hornbill leadbeateri from scan behavioural samples.