Oriental Journal of Social Sciences 2,1 (2013)
Distribution Pattern of Large Trees as Potential Nest Placement Sites for Woodland Nesting Raptors: A Prerequisite to Avoid Disturbance of Raptorn Breeding Sites, Lochinvar National Park, Kafue Flats, Zambia. Chansa Chomba (Corresponding Author) School of Agriculture and Natural Resources, Disaster Management Training Centre Mulungushi University, Kabwe, Zambia.
E-mail:
[email protected] Eneya M’simuko School of Natural resources, Copperbelt University, Kitwe, Zambia. Vincent Nyirenda Zambia Wildlife Authority, Directorate of Research, Planning, Information and Veterinary Services, Chilanga, Zambia.
Abstract:
The distribution pattern of large trees (> 10 m height) as potential nesting sites for woodland nesting raptors were surveyed using field methods in the woodland vegetation community of Lochinvar National Park, Zambia. The distribution pattern of large trees (>10 m height) was carried out in 2011-2012 in Lochinvar National Park. The study assessed the species, numbers and their distribution pattern in the Lochinvar National Park. Survey of such trees was found to be important for securing key nesting sites for raptors. Road drives and foot patrols were used to identify and take GPS coordinates of all trees taller than 10 m. The main objectives of the study were; 1) to collect baseline data for the monitoring big trees as indicators for the health of the woodland, 2) to identify possible breeding sites for large bird species including. Such data would be used by management to conserve breeding sites of large birds including raptors. Trees above 10m in height were few, 3 trees/km2, and their distribution was aggregated, making it convenient to zone such areas as raptor breeding sites which would be easily protected from late fires and other human induced disturbances. Keywords: Tall trees, Species, Lochinvar, Kafue flats, Habitat.
1. Introduction Lochinvar National Park is generally flat lying between 970 – 1,038 m above sea level and is part of the Kafue flats which experiences seasonal flooding. The National Park is divided into three major zones, with each zone having a characteristic fauna and flora. The northern third is a flood plain inundated annually by the Kafue River, which also forms the northern boundary, while the northern part is slightly higher. In 1979, the Government of the Republic of Zambia commissioned the Itezhi Tezhi reserve dam to hold water for the generation of electricity at the Kafue gorge. At the time there were legislative frame works compelling developers to conduct an environmental impact assessment. Subsequently Lake Itezhi tezhi formed. The natural flooding regime which maintained the Kafue flats was disrupted. Major vegetation community changes occurred and continue to take place on the Kafue Flats. The sudden disruption of the natural flooding regime and the ecological dynamics taking place on the Kafue Flats attracted attention of scholars and various studies have been carried out to determine the impact of the disrupted flooding cycle on the ecosystem. The zone is predominantly a woodland area, characterized by mainly species of Acacia, Albizia and Combretum spp. The area is renkown for its rich bird life numbering over 400 species (Leonard, 2005). Of these 52 species are raptors. It is for this reason that Lochinvar National Park and the entire Kafue Flats are christened the Bird Watcher’s Paradise which enthralls ornithologists and amateur bird watchers alike. Prominent among them in the flood plain include the spur winged goose, fulvous and white faced tree ducks, grey purple and goliath herons, reed cormorant, darter, pink backed and white pelicans. Fish eagle and crowned and wattled cranes can be seen in the termitaria zone during the high flood. Secretary bird and Denham’s bustard may also be seen. In the woodland zone, helmeted guinea fowl, Swainson’s francolin, and red-billed hornbill are common. From November through March/April Euro-Asian migrants mingle with resident birds on the flats creating an unrivaled bird watchers’ paradise. The park together with Blue lagoon national park were 43
Oriental Journal of Social Sciences 2,1 (2013)
declared as a Ramsar Site (Wetland of International Importance) in 1991.This brief description is in no way adequate to describe the beauty and richness of Lochinvar National Park. In addition to these species are raptors, a group of birds whose global population status is generally recorded to be on decline (Birdlife International, 2009; Birdlife International, 2012). Since the 1970s, when some preliminary studies were done to identify raptor nesting no follow up studies were done until recently (Chomba and Msimuko, 2013). Results of this study reviewed the importance of large trees in maintaining breeding sites for raptors. With the change in vegetation communities particularly woody plants arising from the impact of the disrupted flooding, and pressure from surrounding human settlements, it has become necessary to gather more information on large trees which serve as breeding and roosting sites for raptors. The growing pressure from illegal human activities such as tree cutting, charcoal production and grazing, underscores the need to monitor large trees. Studies by Wataru ( Wataru, 2009) showed that effects of human impact on large trees were obvious in the woodland area, due to the close distance to the communities (Chomba and Msimuko, 2013). Despite such pressure on the indigenous vegetation communities, no detailed research has been done at least in the last decade. This survey was a follow on the earlier preliminary survey by Wataru (Wataru, 2009) and the objectives were as follows: 1) to collect baseline data for the monitoring big trees as indicators for the health of the woodland, 2) to identify possible breeding sites for large bird species including. Such data would be used by management to conserve breeding sites of large birds including raptors.
2. Material and Methods 2.1 Study Site The research was undertaken in Lochinvar National Park, targeting the southern part of the National park which has a woodland vegetation community (Figure 1, b). The same areas visited by Wataru were selected and interviews with Wildlife Police Officers resident in the area for more than ten years or so was carried out to identify other large trees that might have been omitted by Wataru. Figure 1: a) Location of study area, Lochinvar National Park on the Kafue Flats, b) details of the study area showing the southern portion of the National Park, where the trees were surveyed.
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Oriental Journal of Social Sciences 2,1 (2013)
2.2 Measurements In this survey big trees referred to those above 10 m in height as these could also be easily observed while driving or walking in the National Park. On each tree observed, the researcher recorded species based on Trees of southern Africa and know your trees (Pakgrave 2002), field guides, GPS coordinates, DBH at 1.3 m above ground using a linear caliper, and height was calculated as ealier done by Wataru (Figure 2), where L, the distance between the observer and the tree, and the angle calculated at point where the observer can see the top of the tree and then adding the eight of the observer to the L to determine H as also applied by Banda (Banda, 1995). General observations were made on the tree.
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Oriental Journal of Social Sciences 2,1 (2013) Figure 2: Field method of measuring tree height and mathematical calculation of height. (modified after: Banda, 1995 and Wataru 2009)
H: Height of the tree
L: Distance between H
h´
the observer and 45°
the tree
L Tree
Eye height of the observer
Observer
3. Results 3.1 Species Characteristics 2 A total area of about 24 km was surveyed in which 82 big trees (.> 10m height) were recorded with 2 density of 3.4/km . Twenty two species were recorded, among them six were the most abundant; Xeroderris stuhlmannii was the commonest 22 (26.82 % of total), Burkea africana 9 (10.97 % of total), Sclerocarya caffra 6 (7.31 % of total), Colophospermum mopane 4 (4.87 % of total), and Pericopsis angolensis 4 (4.87 % of total) (Table 1). The rest had less than 4 % sighting frequency. Table 1: Nests recorded during the survey, location, host tree species and possible species of bird, Lochinvar National Park, 2012 Zambia. Species Number Percent relative frequency Mean height (m) Mean DBH recorded of total (cm) Xeroderris stuhlmannii 22 26.82 17 61 Burkea africana 9 10.97 17 45 Sclerocarya caffra 6 7.31 18 65 Albizia harveyi 5 6.09 20 68 Colophospermum mopane 4 4.87 18 65 Pericopsis angolensis 4 4.87 17 43 46
Oriental Journal of Social Sciences 2,1 (2013) Amblygonocarpus andongensis Lonchocarpus cappasa Acacia polyacantha Peltophorum africanum Acacia spp Kigelia africana Acacia tortilis Strychnos spp Acacia nigrescens Albizia versicolor Ficus sycamorous Ficus craterostoma Combretum fragrans Pterocapus angolensis Acacia goetzii Ficus burkeii Combretum spp Erythrophleum africanum
2
2.29
19
53
3 3 1 2 2 1 1 1 2 1 1 1 1 1 1 1 1
3.65 3.65 1.21 2.29 2.29 1.21 1.21 1.21 2.29 1.21 1.21 1.21 1.21 1.21 1.21 1.21 1.21
19 21 19 17 18 16 16 21 19 17 20 17 19 16 21 15 16
64 64 53 41 76 39 42 52 68 47 90 44 53 54 107 27 42
The tallest trees had 21 m height and these were; Ficus burkei, Acacia nigrescens and Acacia polyacantha. The largest tree Ficus burkei which had the largest trunk 107 cm (DBH cm) and was 21m tall (Figure 3a). The other species with 21m height had smaller DBH.
25
120 21 19
15
80
60 9
40 6 5 4
20
3 1
Species Number recorded
Mean height (m)
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1
Mean DBH (cm)
1
1
1
1 Erythrophleum
1
Combretum spp
1
Ficus burkeii
1
Acacia goetzii
1
Ficus craterostoma Combretum fragrans Pterocapus angolensis
Kigelia africana
1
Acacia spp
Colophospermum Pericopsis angolensis Amblygonocarpus andongensis Lonchocarpus cappasa Acacia polyacantha Peltophorum africanum
Albizia harveyi
Sclerocarya caffra
0
Burkea africana
1
2
Ficus sycamorous
2
Albizia versicolor
2
Strychnos spp Acacia nigrescens
3 2
Acacia tortilis
4
5
Xeroderris stuhlmannii
Number recorded; Height (m)
10
0
DBH (cm)
16
15
16
17
17
19
20
21
100
16
16
17
18
19
19
17
18
18
17
17
20
19
20
21
22
Oriental Journal of Social Sciences 2,1 (2013)
Figure 3: a) Species, number encountered, height (m) and DBH of trees > 10m tall b) geographical location of tree clusters > 10m height.
3.2 Distribution of Large Trees The distribution pattern of the big trees was aggregated in five clusters as follows; i) cluster one was about ½ km south of Mansangu Fisheries Research Centre, ii) cluster two was along Kudu drive, iii) cluster three was at camp site, 1.5 km north east of Bwanda hot springs, iv) cluster four was about 1 km south of the Gwisho hot springs, and v) cluster five was along Chunga road north of National Park Headquarters (Figure 3b).
4. Discussion The factors contributing to the distribution pattern of big trees were mainly attributed to altitude and height asl (Figure 1b). Fire was also assumed to be a determining factor contributing to the occurrence of the big trees. Areas near camp sites south of Mansangu Fisheries, for instance, are protected from late fires and, tree cutting and other human induced disturbances. On the other hand, burn marks were often observed in areas further south of Mansangu Fisheries area, north of the National Park headquarters, and west of the airstrip, suggesting exposure to late wildfires. It was assumed that late fires could be responsible for the low frequency of large trees in this area. 4.1 Monitoring Programme We recommend a comprehensive monitoring programme for the nesting sites since the species is classified as vulnerable under IUCN’s red data list.In addition, wild ungulate populations which are the main source of food need monitoring, as their decline would negatively affect the species. Monitoring of large trees which are the potential nesting sites should be incorporated in the Park Ecologist’s routine functions. Human disturbance in potential and confirmed breeding sites should be minimized 48
Oriental Journal of Social Sciences 2,1 (2013)
so the birds do not abandon the nests. As earlier reported by Chomba and Msimuko (Chomba and Msimuko, 2013). Tall trees of the height exceeding 10 m are critical for placement of raptor nests should be protected; confirmed breeding sites should be zoned as low visitor use zones as frequent visitation may lead to nest abandonment, and construction of infrastructure including permanent roads should take into account the need to maintain large trees for raptor nest placements. It was, established that mature trees of more than ten metres in height in areas with minimum human disturbance are critical to successful breeding of raptors on the Kafue Flats, Zambia. Acknowledgement We wish to thank the Regional Manager Mrs. Marina Sibbuku for allowing the researchers to operate in the National Park un interrupted, Mr Wataru Tokura for initiating the survey in 2009, Mr. Benjamin Wishikoti for his skills in nest identification and other anonymous readers that contributed through constructive criticisms. References Leonard, P. (2005) Important bird areas in Zambia. Zambian Ornithological Society, Lusaka. Bird Life International (2009) IUCN Red List of Threatened Species. Version (2010) International Union for Conservation of Nature. Retrieved 23-05-13. Birdlife International (2012) Torgos tracheliotos. In: IUCN (2012) IUCN Red List of Threatened Species. Version 2012.2.) Chomba, C. and M'simuko, E. (2013) Nesting patterns of raptors; White backed vulture (Gyps africanus) and African fish eagle (Haliaeetus vocifer) in Lochinvar National Park, on the kafue flats, Zambia. Open Journal of Ecology, Vol. 3 No. 5, 325-330. ZAWA (2004) Lochinvar National Park general management plan. Chilanga, Zambia. Wataru, T. ( 2009) Monthly report to Zambia Wildlife Authority. Chilanga, Unpublished Report. Palgrave, K. (2002) Trees of Southern Africa. Struik Publishers, Cape Town. Douthwaite, R. J. and van Lavieren, L. P. (1977) A discription of the vegetation of Lochinvar National Park Zambia. National council for scientific research. Lusaka. Banda, R. R. (1995) Exploitation status of five selected mammalian species in Kisiju coastal forest, Dar es Salaam, Tanzania. Unpublished MSc. Thesis, University of Dar es Salaam, Tanzania.
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