Leparkiras 2014 HORNBILL PROJECT REPORT

College of Agriculture and Veterinary Medicine

Faculty of Veterinary Medicine

University of Nairobi

“COMPARISON OF FEEDING ECOLOGY OF VON DER DECKEN (Tockus deckeni ) AND NORTHERN RED-BILLED ( Tockus erythrorynchus ) HORNBILLS DURING THE BREEDING SEASON”

A project report submitted in partial fulfilment of the requirement for the degree of Bachelor of Science in Wildlife Management and Conservation of the University of Nairobi.

Leparkiras Claris Reteti

J42/3070/2010

May 2014.

DECLARATION

This report is my original work and has not been presented for a degree at any other University

Signature: ....………………………………….

Leparkiras Claris Reteti

J42/3070/2010

Date: Month 2014

This work is submitted for examination with my approval as University supervisor.

Sign……………………………………

Dr. Gerald Muchemi.

Date………Month…………2014…………

DEDICATION

I dedicate this project to my family and loved ones. Thanks for supporting me throughout the entire process. God bless you all.

ACKNOWLEDGEMENT

I take this opportunity to express my gratitude first to Almighty God for the gift of life and to the people who have been instrumental in the successful completion of my project in Mpala Research Centre.

I would like to show my greatest appreciation to my field supervisor, Dr. Margaret Kinnaird (Director, Mpala Research Centre). I can’t say thank you enough for her tremendous support and help. I felt motivated and encouraged every time she checks on my hornbill project progress.

I would also like to express my most sincere thanks to my supervisor Dr.Gerald Muchemi. You were always very supportive and a great guide during this project period. Thank you for all the knowledge you imparted in class prior to this attachment, thank you for your wisdom as well.

Special thanks to Meeker Family Fund for sponsoring my stay at Mpala Research Centre.

ABSTRACT

The feeding ecology of two Red-billed hornbills and two Von der decken hornbills’ using camera images obtained during the breeding season were studied in Mpala Research Centre, Nanyuki. Red-billed and Von der decken hornbills have different feeding patterns, Red-billed being more carnivorous at 43.94% as compared to Von der decken hornbill which was28.42% carnivorous and 10.03% frugivorous.

Red-billed and Von der decken hornbill showed almost the same trend as the nesting days progressed on. There was a sharp increase in feeding rates during the egg laying period. This is because the female required a lot of nutrients for egg formation (Meijer & Drent, 1999).When the female is incubating the eggs, the male will be feeding the breeding female only therefore energy demand is low during that time. There is a steady increase when the eggs have hatched; the general trend is for rates to be considerably higher during the nesting period than during incubation, to rise at a peak when the chicks are growing at their highest rate. The male hornbill continues to ferry food and some lining material during this period (Kemp, 1995).

The trend of rate of deliveries throughout the day was almost similar in the two species. Early mornings and late evenings had the lowest frequency of deliveries to the nest. This is because of low temperatures and sometimes it can be really dark in the evening obscuring vision.

Contents List of figures ...... 8 List of Tables ...... 9 CHAPTER ONE ...... 10 1 INTRODUCTION ...... 10 1.1 Background to the study ...... 10 1.2 Problem statement ...... 11 1.3 Objectives of the study ...... 12 1.4 Justification of the study ...... 12 1.5 Hypothesis ...... 12 1.6 Limitations of the study ...... 12 CHAPTER TWO ...... 13 2 LITERATURE REVIEW ...... 13 2.1 Studying hornbills ...... 13 2.2 Feeding ecology ...... 14 2.3 Hornbill’s feeding ecology during breeding season ...... 15 2.4 Food delivery rate during breeding season ...... 15 CHAPTER THREE ...... 17 3 METHODOLOGY ...... 17 3.1 Study Area ...... 17 3.2 Data collection ...... 18 3.3 Data analysis ...... 19 CHAPTER FOUR ...... 21 4 RESULTS AND FINDINGS ...... 21 4.1 Hornbill feeding patterns ...... 21 4.2 Rate of deliveries by male hornbill per hour ...... 22 4.3 Rate of male Red-billed hornbill delivering per day ...... 23 4.4 Rate of male Von der decken hornbill delivering per day ...... 24 CHAPTER FIVE ...... 26 5 DISCUSSION ...... 26 CHAPTER SIX ...... 29 6 CONCLUSION AND RECOMMENDATION ...... 29 6.1 Conclusion ...... 29 6.2 Recommendation ...... 30

APPENDICES ...... 33

List of figures Figure 3.1 : A map of Mpala and its neighbouring ranches ...... …...20 Figure 4.1 : Combined Red-billed hornbill rate of feeding per hour...... 24

Figure 4.2: Combined Von der Decken hornbill rate of feeding per hour...... 24

Figure 4.3 : Jessel rock nest...... 24

Figure 4.4: Batuk loop 6c2 nest...... 25

Figure 4.5: Vanessa 4A1 nest...... 26

Figure 4.6: Water tower nest...... 27

List of Tables Table 4.1 : Combined Red-billed Hornbill feeding pattern...... 23

Table 4.2: Combined Von der Decken Hornbill feeding pattern...... 23

CHAPTER ONE

1 INTRODUCTION

1.1 Background to the study Hornbills (Bucerotidae) are a family of birds found in tropical and sub-tropical Africa, Asia and Melanesia. They are characterized by a long, down-curved bill which is frequently brightly coloured and sometimes has a casque on the upper mandible (Kemp, 1991).

The Red billed Hornbill (Tockus erythrorhynchus ) in particular is widespread over the savannas of sub-Saharan Africa (Fry et al.1988) and ranges from S Mauritania, Gambia, Guinea-Bissau, Guinea, S Mali ,Burkina Faso ,Niger, Ghana, Benin, Togo, Nigeria, Chad, N Central African Republic, Sudan, Ethiopia, Somalia, Kenya, E Uganda and Tanzania(Kemp,1995). On the other hand, the Von der Decken's Hornbill (Tockus deckeni ) is a hornbill, found in East Africa, especially to the east of the East African Rift and ranges from S Ethiopia, S Somalia, Kenya; NE,W to Kerio Valley ,E to Lake Turkana and Samburu district, S to Lake Bogoria, Tanzania and Uganda(Kemp,1995). It is mainly found in thorn scrub and similar arid habitats.

Both Red billed Hornbill (Tockus erythrorhynchus ) and Von der Decken's Hornbill (Tockus deckeni ) are listed as least concern in the IUCN Red list category and criteria. It is important to note however that the population trend for both Red billed Hornbill and Von der Decken's Hornbill are decreasing whereas the global population size have not been quantified.

The two species of Hornbills described above are omnivorous, taking insects, fruit and seeds. They feed mainly on the ground and will form flocks outside the breeding season. However the proportion of insect to fruit and seed intake is yet to be determined. Moreover, there has been little study carried out to determine the rate of food delivery between male Von der decken hornbill and male Red- billed hornbill.

It is worthwhile to note that there have been studies carried out to determine the role different foods taken by the two species of Hornbill play in their bodies during the breeding season. Leighton 1982 described the fruits eaten by hornbill as falling into three categories; those rich in carbohydrates and water, especially figs; a variety of drupes and capsules that are rich in fats or lipids; and some watery fruits in thick husks. Alan Kemp, 1995 also described that animal sources of food have high protein content important for tissue formation and body growth and hence are high in demand during the time chicks are growing in the nest.

In addition to fruits and animal foods, special food items such as empty snail shells and millipedes are important during breeding. The empty snail shells prior to egg-laying are possibly a source of calcium salts for eggshell-formation. Millipedes during breeding serve mainly as a source of sealing material for the female or chicks in the nest.

Little study has also been carried out on food delivery by male. Alan Kemp, 1995 described that the number of visits to the nest depends on whether the food is carried singly or collectively, on how many birds are provisioning the nest, and on the stage of the nesting cycle, with maximum demand coming later when the chicks have to be satisfied.

This study hence aims at determining the feeding patterns between male Von der decken hornbill and male Red-billed hornbill and the rate of male delivering to the nest during the breeding season.

1.2 Problem statement Research on Von der decken and Red-billed hornbills has been greatly focused on their breeding ecology and role in seed dispersal of woody plants but little information on what they feed on during the breeding season. It is therefore important to know what they feed on during the breeding season because it influences species survival.

During the breeding season male Von der decken and Red-billed hornbills carries fruits, insects and sometimes grass and delivers it to the female. The Red-billed and Von der decken hornbills are both omnivorous but the proportion of insects to fruits has never been determined in the previous studies. According to Kemp, 1995 Red-billed hornbill are almost exclusively insectivorous whereas Von der decken partly insectivorous and partly frugivorous.

The rate of deliveries by the male von der decken to the nest has not been determined but in male Red-billed it is <1-17/hr, and it is highest when chicks are half grown and very vocal (Transvaal: Kemp 1976a), and rising to 50/hr in the morning (Wambuguh 1988).This study will determine delivery rates of von der decken male and compare delivery rates between this two savannah species. It is of paramount importance to know delivery rates because they might correlate either to clutch size or average body mass.

1.3 Objectives of the study General objectives

To compare the feeding ecology of male Von der decken and male Red-billed hornbill

Specific objectives

a) To compare the feeding patterns between male Von der decken hornbill and male Red-billed hornbill. b) To compare the rate of food delivery between male Von der decken hornbill and male Red- billed hornbill.

1.4 Justification of the study Feeding ecology has influence on timing and success of reproduction, mortality and the extent of social behaviour that develops in a species (Stephan, 2007). It therefore important to know the causes of variations in omnivority whether it because of the number of the eggs laid or is it just a survival tactic. Knowing the rate of male delivering to the nest will enable us to know energy investment during the breeding season in savannah hornbills.

This study targets other researchers interested in studying hornbill feeding ecology during the breeding season while using images from camera traps. Camera traps is one of the latest technologies and can apply to other research fields. It is more effective compared to field observation because it takes photographic images day and night and saves them automatically.

1.5 Hypothesis 1. Red-billed hornbills are more carnivorous than frugivorous compared to Von der decken hornbills. 2. The rate of feeding by the male hornbill increases during the day 3. The rate of feeding by the male hornbill increases during the egg laying and when the chicks have hatched and are growing.

1.6 Limitations of the study Time was the greatest limitation. The time it took to enter one hornbill nest into Ms. Excel is two weeks therefore I couldn’t manage to enter six nests. I managed to do only four, two Red-billed hornbills and two Von der decken hornbills

CHAPTER TWO

2 LITERATURE REVIEW

2.1 Studying hornbills The hornbills and ground-hornbills comprising the family Bucerotidae are charismatic land- birds that have long been the focus of research attention. They are among the world’s most recognisable birds, with many species exhibiting large body size, spectacular enlarged casques, striking black-and-white plumage, and loud, far carrying calls. The decurved bill and projecting casque from which the hornbills derive their common name is one of the most obvious features which assigns them to the avian order Bucerotiformes (Sibley and Monroe 1990;Sibley and Ahlquist 1991).All species of Tockus posses small ridged casques (Margaret& Timothy,2007) and most of the 54 species currently recognized as comprising the Bucerotiformes occupy forest of some description with only about a quarter in savannah or steppe and all but one of these in Africa (Kemp,1995)

Many hornbills inhabit forest environments, where they qualify as keystone species, due to their role as important seed dispersers (Whitney et al. 1998, Whitney and Smith 1998, Holbrook and Smith 2000, Kemp 2001). The larger species utilise extensive home ranges, and are thus sensitive indicators of environmental degradation (Kemp 1995). Hornbills are important resources for indigenous peoples from West Africa to New Guinea, as food items and as sources of feathers, beaks and other parts used in cultural activities (Kemp 2001).

Threats to the survival of large hornbill species in Asia have long been recognized. Many of these species are island endemics from the Philippine and Malaysian archipelagos, whose restricted ranges make them particularly vulnerable to habitat destruction and hunting pressure (Kemp 2001). Five species of Asian hornbills were placed on the first CITES lists in 1975, and all species in the Asian genera Aceros, Buceros, Anorrhinus, Anthracoceros and Penelopides were listed on either Appendix I or Appendix II by 1992.

In contrast, none of the 23 African hornbill species are listed on any of the CITES appendices, and none are currently listed as Vulnerable, Threatened or Endangered by IUCN (nomenclature of African hornbills follows Kemp 2001 and Dickinson 2003). Only two African species, the Yellow-casqued Hornbill ( Ceratogymna elata ) and the Brown-cheeked

Hornbill ( Bycanistes cylindricus ) are classified as Near-threatened by IUCN, the lowest ‘at- risk’ category (IUCN 2004).

2.2 Feeding ecology All hornbill species are omnivorous, eating animal and plant foods in proportions that differ between and within species, between seasons and different age and sex classes. Certain properties of each food category be it animal (arthropods ,small vertebrates) or plant (mainly fruits) have different effects on hornbill feeding ecology ( Kemp,1995).

Fruits eaten by hornbills fall under three categories: those rich in carbohydrates and water, especially figs; a variety of drupes and capsules that are rich in fats or lipids; and some watery fruits in thick husks (Leighton 1982). Beeher (1983) and Leighton (1986) argue that animal prey tends to be more evenly and thinly distributed than fruits, both spatially and seasonally. It is usually more elusive and difficult to harvest, all of which means hornbills have to spend longer periods for animals to reap equivalent returns.

Von der decken and Red billed hornbills which is the subject of our study are omnivorous, eating animal and plant foods in proportion that differ between this two species. This two species occupy the savannas of Africa which are rich in small animals (Crome, 1975) .Certain properties of each food category, be it animal (arthropods, small vertebrates) or plant (mainly fruits) have different effects on hornbill feeding ecology (Alan Kemp, 1995).

Red billed hornbill is more carnivory than frugivorous whereas Von der decken is partially carnivorous and partially frugivourous (Alan Kemp, 1995). Red billed hornbill obtains almost all food on the ground (94% of items Kenya Lack, 1985), searching actively while running about. It feeds mainly on insects, small arthropods and geckos (Wambuguh 1988).A few fruits and seeds are eaten, such as Boscia senegalensis and Commiphora holtzianan ,and in some areas and seasons, especially in E and W Africa, these may be frequent and important in their diet (Elliott 1972;Ge’rald Morel in litt. 1984;Lack 1985;Wambuguh 1988)

Von der decken on the other hand forages mainly on the ground (93% of items;Lack 1985),where it runs about in search of food or drops down repeatedly to collect items(Jackson 1938).It feeds mainly on small invertebrates, as well as berries, especially Commiphora and Cissus fruit in season, such as Dicrostachys ,and some buds (Alan Kemp,1995).

2.3 Hornbill’s feeding ecology during breeding season Hornbills exhibit a peculiar breeding habit where the females seal themselves into the nest cavity by closing off the cavity entrance with a plug made out of mud and faeces (Kemp, 1995).Male assistance in that effort varies among species, but is generally limited to provisioning additional mud, some millipedes, and nest lining material.

In both Von der decken hornbill, the female remains concealed in the nest for 80-82 days whereas in Red-billed hornbill for 65-99 days(Alan Kemp,1995).This includes egg laying, incubation and chick rearing. For the entire period, the male is responsible for providing the entire female and off spring nutritional requirement, doing so by transferring food to the female through a small, vertical slit that is retained in the nest plug (Klassen et al 2003).

Male are cooperative breeders in both von der decken and red billed hornbills. They ferry food to the incubating female. Species also differ in size, duration of nesting cycle ,number of eggs laid and chicks raised(Poonswad et al.1987;Kemp 1995),all of which influence the nutrient requirements of nest inmates. Food delivered to the nest also varies between species, habitats, seasons and nesting cycle.

Animal foods tend to have higher protein content than fruits and come in packages with less waste, especially when the prey is small vertebrate. Animal sources of food have high protein content important for tissue formation and body growth and hence are high in demand during the time chicks are growing in the nest (Alan Kemp, 1995).

2.4 Food delivery rate during breeding season The number of visits to the nest depends on whether the food is carried singly or collectively and the stage of nesting cycle with maximum demand coming later when the chicks have to be satisfied (Alan Kemp, 1995).

Information on food delivery rate is only available for the Red-billed hornbills where single food items are delivered to the nest at mean rates of <1-17/hr, highest when chicks are half grown and very vocal (Transvaal; Kemp 1976a) and rising to 50/hr in the morning (Wambuguh 1988).

In Kenya, male Red-billed hornbill delivers mainly insects of mean length 1.3-4.8cm at different nests especially Lepidoptera, Orthoptera, and Coleoptera, with fruits such as Premna resinosa ,Boscia coriaceae ,Commiphora holtziana ,C.riparia ,and Dictyoptera forming a lesser proportion of the diet (Wambuguh 1987).

In Von der decken hornbills, the male feeds the chicks with single items brought in the bill (Alan Kemp, 1995).Information on delivery rates is unavailable.

CHAPTER THREE

3 METHODOLOGY

3.1 Study Area This research was carried out from 1 March to 15 April,2014 at the Mpala Research Centre in Laikipia ( Figure 3.1 ).Mpala Research centre is a biological field station managed by the Kenya Wildlife Service, National Museums of Kenya, Princeton University, and the Smithsonian Institution (Miller & Lazell, 2001). It is located 50 km north of the Equator (0 o 17’N, 37 0 53’E), North West of Mount Kenya, in the semi-arid savannah of the Laikipia County at 1650m.

Precipitation at MRC normally consists of heavy rains from April to July and light rains in October through November (Keesing, 2000).The climate is semi-arid, with an annual rainfall of about 550mm (Gadd, Young and Palmer, 2001)

The area is underlain by soils classified as well- drained, moderately deep to very deep, dark reddish brown sandy clay loam to clay loam soils developed from metamorphic basement rocks (Ahn & Geiger 1987).Soil types consist of red, sandy soils and dark soils with high clay content also called “black cotton”. Both soil types are characterized by a landscape mosaic with numerous isolated ‘glades’. These features are treeless, have high levels of mineral nutrients and are preferentially used by wild and domestic herbivores.

Vegetation is dominated by species of Acacia, and vegetation composition is quite different between red and black soils. Acacia drepanolobium is the dominant tree species at the study site accounting for>98% of the over story vegetation(Young et al.1998) A.mellifera ,Balanites aegyptica, Cadaba farinosa , Lycium europium and Rhus natalensis are other woody species present. The grasses Brachiaria lachnatha,Lintonia nutans,Pennisetum mezianum,Penisetum stramineum and Themeda triandra, and the forbs Aerva lanata,Commelina spp.,Dyschoriste radicans and Rhinacanthis ndorensis comprise majority of herbaceous species at the study site(Young et al.1998).

Large mammalian herbivores common at the study site include African elephants( Loxodonta africana ),giraffes( Giraffa camelopardalis ),Grevy’s zebra( Equus grevyi ),Burchell’s

17 zebra( Equus burchelli ),Grant’s gazelles( Gazella granti ) and domestic cattle( Bos Taurus : Young et al.1998)

Figure 3.1 : A map of Mpala and its neighboring ranches.

3.2 Data collection Secondary data on Von der decken and Red-billed hornbills which has never been analysed before was used. The data was obtained from Mpala Hornbill project under a study on hornbill’s breeding behaviour from April-July, 2013. The study concentrated on two Von der decken hornbill nests (VDD nests) namely VDD_ Water Tower, VDD_VanessaGlade-4a1 and two Red-billed hornbill nests (RBHB) namely RBHB_ Batuk Loop 6c2-3 and RBHB_jesselrock1B1.

The raw data was obtained from camera trap images at the hornbill nests which were then entered in an Ms Excel sheet. Each hornbill nest has several folders with different dates indicating when the photographs were taken. Individual folder in the hornbill nest data had a separate Ms Excel sheet in which data was entered.

The Ms Excel sheet had sixteen columns including; Image No., date, time, temperature, identity 1 (male), behaviour, at the nest, item in bill, item identity, delivered/removed, identity 2 (female),behaviour, at the nest, item in bill, item identity and delivered/removed.

In Identity 1(male) column, if the male hornbill was at the nest “male” was entered and if not “x”. Behaviour illustrated the male hornbill’s activity at the nest whether it was flying, perching or feeding. At the nest indicated whether the male hornbill was at the nest or not and it was entered as “y” for yes or “n” for no respectively.

Item in bill column indicated whether the hornbill had something in the bill or not and it was indicated as “y” for item in the bill and “n” for no item in the bill. Item identity clearly stated the item in the male hornbill’s bill whether it was an insect, grass, ugali, fruit or seed pod e.t.c. For unknown items which occurred when the image had poor lighting or when the bill was facing away from the camera “unk” was indicated. Delivered/removed was indicated “y” for yes when the male hornbill successfully delivered the item in the bill to the female and chicks and “n” for no when the delivery was unsuccessful or when the bill was withdrawn from the nest with the item.

The same process applied when the female emerged from the nest and was feeding the chicks alternating with the male. The female hornbill data in this study was not important and therefore not much was focused on the female’s activity.

Lastly, in instances where both the male and female were not at the nest, “setup” was indicated in the behaviour column. Sometimes predators such as genet cats and squirrels frequented the nest at night and therefore entered in the behaviour column. Elephants, baboons, cows and camels sometimes came to graze and browse in the nest and are indicated in the behaviour column.

3.3 Data analysis Data from each folder of individual nests were organized into individual Ms. Excel master files by sorting out instances where the male bird was at the nest. Data in which the male hornbill was at the nest was retained .

In the individual master files,”sequence” and “30 seconds” columns were added. The importance of the 30secs column was to help in sequencing data. Data was then sequenced using the logical test formula in Ms Excel as illustrated below;

=(x3-x2)*30secs was applied in the 30 seconds column while =if (abs(x3-x2) <=$f$2, e2, e2+1) was applied in the sequence column.

Pivot tables were then created to help in summarizing and analyzing the data. The pivot table created included; Food items, rate of feeding per hour and rate of feeding per day.

CHAPTER FOUR

4 RESULTS AND FINDINGS

4.1 Hornbill feeding patterns Food items Frequency Percentage Insect 1549 43.94% Fruit 468 13.28% Seed 468 13.28% Vertebrate 5 0.14% Non-edible 17 0.48% Unk 1018 28.88% Total 3525 100 Table 4.1 : Combined Red-billed Hornbill feeding pattern

Table 4.1 clearly shows that Red-billed hornbills take a higher percentage of insects at 43.93% whereas fruits and seeds come much lower at 13.28% in both. Non edible things such as feather, grass and leaves at 0.48 %.Vertebrates such as small birds in form of animal parts were taken at 0.14%.Unkown items accounted for 28.88%.

Food items Frequency Percentage Insect 1478 28.42 Fruit 522 10.03 Seed 228 4.38 Vertebrate 69 1.33 Chapati&ugali 200 3.85 Non-edible 202 3.88 Unknown 2502 48.10 Total 5201 100 Table 4.2: Combined Von der Decken Hornbill feeding pattern

Table 4.2 shows that Von der decken male delivered a much lower percentage of insects compared to Red-billed male hornbill at 28.42%, fruits and seeds at 10.03% and 4.38% respectively. Vertebrates which included rats, frogs, lizards, fish and chameleon percentage was much higher at 1.33% compared to Red-billed hornbill. Chapati&ugali and non edible

21 things had almost the same percentages at 3.85% and 3.88%.Unkown items accounted for 48.10%.

4.2 Rate of deliveries by male hornbill per hour

1.2

0.8

0.6

Frequency Feeding 0.4

0.2

0 6 7 8 9 10 11 12 13 14 15 16 17 18 Hours

Figure 4.1 : Combined Red-billed hornbill rate of feeding per hour

Figure 4.1 shows that the frequency of feeding was maximum at (9 00hrs) in the morning where the rate of deliveries was 1item/hr and was lowest early morning and late evening. Rate of feeding steadily rose up in the morning hours and dropped smoothly late afternoon.

1.8 1.6 1.4 1.2 1 0.8

Frequency Feeding 0.6 0.4 0.2 0 6 7 8 9 10 11 12 13 14 15 16 17 18 Hours

Figure 4.2: Combined Von der Decken hornbill rate of feeding per hour

Figure 4.2 shows that the frequency of feeding was highest at (11 00hours) at 1.7 items/hour and lowest at early morning (6 00hours) and late evening (18 00hours).There was a sharp rise from 9 00hours to 11 00 hours .Rate of feeding steadily rose up in the morning hours and dropped smoothly late afternoon.

4.3 Rate of male Red-billed hornbill delivering per day

60 Egg laying 50

Hatching 40

30 Feeding Frequency 20

Days

Figure 4.3: Jessel rock nest

Figure 4.3 shows that the rate of feeding increases rapidly from day 3 to day 11 which corresponds to egg laying period. It then reduces and stabilizes from day 18 to day 32 which corresponds to incubation of eggs by the female. It rises steadily from day 33 to day 46 which relates to the days the chicks have hatched and the male is feeding the chicks and female.

25 Egg laying Hatching 20

15 Feeding

Figure 4.4: Batuk loop 6c2

Figure 4.4 shows that the rate of feeding increases rapidly from day 2 to day 7 which corresponds to egg laying period. It then reduces and stabilizes from day 15 to day 25 which corresponds to incubation of eggs by the female. It rises steadily from day 25 to day 46 which relates to the days the chicks have hatched and the male is feeding the chicks and female.

4.4 Rate of male Von der decken hornbill delivering per day

70 Egg laying Hatching 60

30 Frequency 20

Day

Figure 4.5: Vanessa glade4A1

Rate of feeding increases rapidly from day 4 to day 9 which corresponds to egg laying period. It then reduces and stabilizes from day 18 to day 32 which corresponds to incubation of eggs

24 by the female. It rises steadily from day 55 to day 50 which relates to the days the chicks have hatched and the male is feeding the chicks and female. There is a steady decline after day 50 because the female is out and is assisting the male feed the chicks.

30 Egg laying Hatching 25

Frequency 10

Day

Figure 4.6: Water tower nest

Figure 4.6 shows that the rate of feeding increases rapidly from day 4 to day 9 which corresponds to egg laying period. It then reduces and stabilizes from day 10 to day 25 which corresponds to incubation of eggs by the female. It rises steadily from day 25 to day 60 which relates to the days the chicks have hatched and the male is feeding the chicks and female. There is a steady decline after day 62 because the female is out and is assisting the male feed the chicks.

CHAPTER FIVE

5 DISCUSSION 5.1 Test of hypothesis and predictions

My first hypothesis was that Red billed hornbills are more carnivorous compared to Von der decken who are partially carnivorous and partially frugivorous (Kemp, 1995).There was a positive response to this hypothesis, this is because Red billed hornbills were 43.94% carnivorous whereas the Von der decken 28.42% carnivorous and 10.03% frugivorous.

My second prediction was that the rate of feeding by the male hornbill increases during the day, however, contrary to this hypothesis the rate of feeding increased sharply from mid morning and decreased late afternoon in both species.

My third hypothesis was that the rate of feeding by the male increased during egg laying and when the chicks have hatched. My results indicate a positive response to this because the graph peaked during incubation and when the chicks had hatched.

5.2 Feeding patterns comparison

The explanation to the differences in percentages is that Red-billed hornbills are more carnivorous as compared to Von-der decken (Kemp, 1995). Red-billed hornbill had a higher percentage of insects in its diet at 43.94% whereas Von der decken at 28.42%.The insects eaten by the two species included butterflies, caterpillars, grass hoppers and other types which were not identified. Vertebrate food items in form of frogs, chameleons, fish, lizard and rat were very low in percentages because it takes so much energy for a small bodied hornbill to hunt down a vertebrate.

Animal foods have higher protein content than fruits. They are important for tissue formation and body growth hence are high in demand during the time that chicks are growing up in the nest. In Von der decken there is increased animal component of the diet delivered to the nests during the breeding period despite it being frugivorous( Kemp,1995)

Fruits taken by hornbill offer two basic energy rewards, carbohydrates in form of sugars and starches, and lipids, made up of fatty acids(Kinnaird &O’Brien,2007).Fruits are taken when perfectly ripe, and when high in sugars and low in phenol compounds(Kemp,1995).Seeds supplement protein diet which is important in tissue formation. Von der decken hornbill supplemented the low percentage of animal items with fruits.

Non edible items like feathers, leaves, grass and tree bark were brought by the male Von der decken at 3.88 % and the male Red billed at 0.48 %.The non-edible items are used to raise the level of the nest floor and for lining the nest (Roots, 1968).The lining also contributes towards absorbing food and excretory matter(Kemp,1995).

Unknown items are the ones delivered to the nest when the male is facing away from the camera or when the image is taken late evening and it appears dark.

5.3 Comparison of rate of deliveries per hour

The rate of feeding peaked up from early morning and dropped late afternoon, the peaking up can be explained by favourable temperatures, and the dropping in the afternoon can either be the female is satisfied or the male is tired from feeding all day.

Rate of feeding per hour can also be affected by rainfall and the availability of food in the habitat.

5.4 Comparison of rates of deliveries per day

When the female is incubating the eggs, the male will be feeding the breeding female only therefore energy demand is low during that time. The female does not to leave the eggs to take food from the male at the nest entrance; she just reaches out her long neck. In Monteiro’s hornbill Tockus monteiri, of the same genus as the Red-billed and Von der decken hornbill, body weight increases during the incubation, suggesting deposition of additional reserves and that regrowth of flight feathers is not too taxing (Kemp, 1995).

There is a steady increase when the eggs have hatched; the general trend is for rates to be considerably higher during the nesting period than during incubation, to rise at a peak when the chicks are growing at their highest rate. The male hornbill continues to ferry food and some lining material during this period (Kemp, 1995).

According to Wambuguh, 1987 Red-billed hornbills feeding rates and food size delivered to the nest were highest soon after the female had entered and was laying and after hatching. This has been reflected clearly in the results. Similarly, the same trend happens in the Von der decken hornbill.

CHAPTER SIX

6 CONCLUSION AND RECOMMENDATION

6.1 Conclusion Feeding ecology is an important aspect of any living organism day to day life. Red-billed and Von der decken hornbills depend on the African savannas for their food and nesting ground. They are cavity nesters and with disappearing woodlands their population trend will continue to decline. We should therefore strife to conserve our savannas for the survival of this species.

The types of food required by each hornbill species are the primary determinant of when, where, and how they feed during their daily activities. Breeding season requires more specific foods for such as minerals needed for eggshell-formation or special proteins for feather growth. It is important to note that generally the number of visits to the nest depends on whether the food is carried singly or collectively, on how many birds are provisioning the nest, and on the stage of the nesting cycle, the maximum demand coming later when the chicks have to be satisfied(Kemp,1995).

Lastly, of importance to note is predation of hornbill nests and whether it has effect on the species survival. Genet cats, lizards, mongoose and squirrels regularly visited the two Tockus spp of discussion during the night. More research should be done on this to ascertain whether they influence survival rates of the Von der decken and Red-billed hornbills.

6.2 Recommendation The use of camera images in the study of feeding ecology of hornbills is an emerging tool of research. A camera trap is an automated digital device that takes a flash photo whenever an animal triggers an infrared sensor. The use of camera trap technology has revolutionized hornbill research and conservation by enabling scientists to collect photographic evidence with minimal disturbance.

Predation of hornbill nests could be investigated by observation of the wild animals attempting to break into the nest .Mongooses, genet cats and squirrels were mostly spotted in the nest. Nesting behaviour and feeding ecology of the hornbills can be researched too by camera traps. The percentage of visits could be determined to know which one posses the most or the least threat to survival.

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APPENDICES

Male Red-billed hornbill perching at the nest

Male Von der decken hornbill feeding the female at the nest