EFFECT OF BURNING ON ABUNDANCE AND DIVERSITY OF BIRD SPECIES IN SAADANI NATIONAL PARK
Burning has been an important tool of management in most protected areas of Tanzania. Fire has also been an important determinant of structure and function of Savannah Ecosystems, apart from its importance, relatively little is known about the effect of fire on avifauna biodiversity in this country. The study was conducted in the southern part of Saadani National Park, and it aimed at determining the effect of burning to the abundance and diversity of bird species found in a particular area, as well as the difference in birds abundance between woodland and grassland habitats.
The method used was line transect method, where by birds heard and seen were recorded as well as the habitat and the condition of the habitat whether it was burnt or unburnt. The study revealed significant difference in diversity of bird species between woodland (H = 3.4926) and grassland habitats (H = 2.7973), (t= 0.806) in both burnt and unburnt areas, while there was not any significant effect of burning on birds diversity in both woodland and grassland. Also the abundance of birds was high in woodland than in grassland habitat in both burnt and unburnt areas. (’ U’ and .560).
ACKNOWLEDGMENTS
Firstly I would like to thank my Almighty God for his protection and guidance, and my parents for their support in my daily life.
Secondly, I would like to express my sincere appreciation to my project supervisor Mr. Chacha Werema, for his support, guidance, advice and knowledge to an understanding of how to carry out each step involved in this research project.
Special thanks should go to the University of Dar-es-Salaam College of Natural and Applied Sciences through Department of Zoology and Wildlife Conservation for offering the course to its students doing Bsc. (Wildlife) as it imprints with them the basic knowledge and skills on research activities as new and young scientists of the present.
I am grateful to Tanzania National Parks (TANAPA) and Saadani National Park (SANAPA) authority in particular, for allowing me to carry out my study in their rpotected area.
Thanks to all people who gave me hope, encouragements and advices during and after the time of collecting data, these include; Mr. Mfaume Hussein, who devoted some of his time in guiding me in collecting data, Mr. Michael Kimaro, Deogratius Lorri, Robert Mutai, and all of my course mates.
Finally, I would like to extend my gratitude to all those who helped in funding my research project, including: High education students loan board (HESLB) without forgetting my family, their love and support is irreplaceable.
GENERAL INTRODUCTION
Birds are organisms which fall under the class Aves of kingdom Animalia. Always the abundance and distribution of living organisms is dictated by the environmental conditions, natural catastrophes, daily human activities and lifestyles in general. In protected areas of Tanzania, burning has been the main ecological management tool. Being used in ecological management, burning leads to modification and alteration of many mega and micro-habitats of species temporarily or permanently depending on the recovery ability and the sensitivity of a particular species to burning, hence resulting on affecting the communities of particular area.(O`Reilly et al., 2006)
Habitat structure and anthropogenic disturbance have been identified as some of the factors shaping the density and distribution of species across a landscape. Fire is an important determinant of many aspects of savanna ecosystem structure and function. However, relatively little is known about the effects of fire on faunal biodiversity in savannas (O`Reilly et al., 2006).
Despite the importance of fire in savanna ecosystems, most fire studies have focused on the effects of fire on vegetation; less attention has been paid to the effects of fire on faunal diversity (Parr & Chown., 2003).
In addition to scale effects, responses of plant communities to burning are strongly influenced by the time of year at which the burn is applied, with dormant season (spring and fall) burns tending to reduce diversity by promoting the dominance of a limited number of warm season grass species and growing season (summer) burns tending to increase community diversity by promoting generation and growth of a larger number of late-flowering grasses and forbs. Managers who appropriately consider the effects of scale, local conditions, timing, and frequency of burning and mowing can achieve a wide range of effects on plant community diversity. Thus, further research on the comparative effects of mowing and burning has value, particularly where scaling considerations are explicit, in helping managers to predict effects of management actions on different sized areas. ( Fred et al., 1999, unpublished)
Fire can affect forest birds positively or negatively, depending on the type and extent of fire and the particular life history of the species involved. Direct effects, such as mortality due to fire, are generally considered to be minor. Rather, fires influence birds indirectly through habitat modification, changes in food supply, or changes in abundance of competitors and/or predators (Rotenberry et al., 1995). The effects of fire on habitat structure, floristic composition, and food resources may be especially important, singly to or in combination, as many birds respond strongly these features of their habitat (MacArthur et al., 1966, Koplin 1969, Rotenberry 1985).
The effects of burning differ in grasslands versus shrublands. In native grasslands, burning has a strong effect on the vegetation, which, in turn, affects a suite of grassland and shrubland specialists. In an 8-yr study at Kennebunk, Maine, prescribed fire affected all eight nesting species that breed at that site. (Vickery et al., 1999)
STATEMENT OF THE RESEARCH PROBLEM
Few studies have been conducted in determining the effect of fire to the birds in the East Africa, but most of were directed to certain types of species, and there is no study which has been done in Saadani National Park, which is a unique protected area combining coastal and forest ecology. Since birds are among sensitive species to disturbance, this study will open doors to the use of birds as indicators of ecological disturbances.
MAIN OBJECTIVES
The main objective of this study is to determine the effect of burning as a type of disturbance to the abundance and diversity of bird species in Saadani National Park, and the interaction between burning and vegetation types to the abundance and diversity of bird species.
SPECIFIC OBJECTIVES
I. To determine the difference in abundance and diversity of birds species between grassland and woodland habitats.
II. To assess the effect of shoot growth post-fire on abundance and diversity of birds species in Saadani National Park.
SIGNIFICANCE OF THE STUDY
This study will provide information necessary in avifauna conservation, since it has shown their reactions toward burning, and since burning is the major tool of ecological management in most of our protected areas, the study has helped the scientists and conservationists to understand the suitable time for burning their environment and which type of fire is to be used so as to ensure the survival of the birds found in their particular areas.
This study has opened door to other scientist to carry out studies which will determine the real causes of changing in population of bird species after burning by considering their daily environment utilizations and food.
LITERATURE REVIEW
Both historic and present-day vegetation dynamics in grasslands are mediated by variation in disturbance intensity and frequency such as periodic fire and ungulate grazing. This in turn influences the avian community via the resulting heterogeneity of grassland vegetation. Knowing that most grassland birds select nesting habitats with very specific characteristics, maintaining or restoring spatial-temporally variable disturbances that produce heterogeneity in herbaceous systems is critical to the conservation of grassland bird communities recently illustrated the importance of long-term grassland heterogeneity, concluding that intermittent, patchy disturbances derived from grazing and inter and intra-seasonal fire were essential in maintaining the intra-seasonal fire were essential in maintaining the variety of disturbance levels needed by various species in tall grass prairie. (Coppedge et al., 2008)
Effects of low and moderate-intensity burns are less dramatic. In the short-term, bird species richness may increase in moderate-intensity burns; because bird’s characteristic of both burned and unburned forest may use the area (Taylor and Barmore., 1980). Low-intensity bums can create or maintain habitat for species that prefer open forest (Marshall 1963, Hutto 1995).
First, fires vary widely in extent, intensity, and duration (Rotenberry et al., 1995). Because of this variation in fire behavior, the effects of fire on birds and their habitat also varies widely. Fire affects all aspects of the ecology of the savanna individual plants, plant communities, animals and their habitats, nutrients, water catchments and down-stream hydrology. In turn, fire regimes have various effects ranging from major short-term impacts associated with frequent high-intensity fires through to slower, longer-term changes associated with total fire exclusion. In order to maintain savanna species diversity at landscape scales, an ideal fire regime requires the development of a fine-scale mosaic where burnt patches represent a range of fire intensities and fire ages from recently burnt through to long unburnt. All land managers need to understand the ecological consequences of fire management (Woinarski et al., 1998)
At the small spatial scale, some birds, e.g., Nystalus maculatus, that forage and build their nests in burrows or on the soil surface showed reduced densities and some disappeared from the burned areas. However, at the large spatial scale this species increased in abundance post-fire. This may be because they follow invertebrate colonization on the newly sprouting plants. (Cintra and Sanaiotti., 2005)
Ground-walking bird species may use unburned forest edges as refuges from fire (R.C., pers. obs.). Even birds with limited flight capacity, e.g., such as tinamous, were seen flying over 2 m high flames. In the savanna itself, unburned areas are available for use as nesting sites for species such as Nystalus maculatus, which nests underground in a tunnel; Aratinga aurea, which nests in termite nests; and woodcreepers, which nests in tree holes, may escape fire damage. As an example, abundance of Myiarchus ferox changed little post-fire. In contrast, Myiarchus tyrannulus, which use tree holes, disappeared from the 20 ha area, but there was little effect on their abundance at the 2000 ha scale. In addition, an active nest with two nestlings of Myiarchus tyrannulus was found in a tree hole 2 m above the ground in November 1997 just a few days post-fire. (Cintra and Sanaiotti., 2005)
HYPOTHESES
There is no significance difference in abundance and diversity of bird species between grassland and woodland habitats.
There is no correlation between abundance and diversity of birds against time post-burn.
MATERIALS AND METHODS
The study was carried in two different types of habitats, woodland and grassland which were formally unburnt. By using the line transect method I determined the species of birds found in both types of habitats which were unburnt areas, followed by monitoring changes in species diversity and abundance of birds in the particular area for four consecutive post-fire weeks. Data were collected during morning time starting at 06:00am to 09:30am, under the area of five kilometers in length. All birds seen and heard were recorded including the state and condition of the habitats they were found for all four weeks of data collection, Binoculars and a guide to identification of bird's book were used during the study. The study was conducted on foot since this southern part of Saadani National Park is known not to have dangerous animals.
STUDY SITE
The study was conducted in July to August 2011 in southern part of Saadani National Park. As in many regions of East Africa near the equator rainfall is bimodal. The climate is coastal, hot and humid. The average temperature lies between 25 and 30 degrees Celsius. Humidity is high throughout the year, reaching levels of up to 90% in the rains. The south east monsoon (trade wind) locally referred to as “kusi” from the Swahili word for South, “kusini” blows from April to October. The northeast monsoon, the “kaskazi”, blows from October to March, combining the large open grassland, the Acacia zanzibarica woodland, coastal vegitations, riparian vegetation and scrub forest, hence providing refuge to diverse species of avifauna. The study was achieved by conducting a line transect starting from Kinyonga campsite to Tank number 109, providing the length of five kilometer from the camp site and about two kilometer to the Wami gate.
DATA ANALYSES
The data collected during the study was analyzed in tabular forms and abundance was analysed by using Mann-Whitney U-test and special t-test, while the diversity of bird species was determined by using a Shannon Wiener index with 10000 random partitions. (Solow, 1993)
RESULTS
The total number of bird species identified in both woodland and grassland habitats, was 61, where by 29.51% (18) of these species were found in grassland and 70.49% (43) of the total species were found in woodland habitat, while some species like helmeted guinea fowl were observed in both grassland and woodland habitats, but they were found in both burnt and unburnt grassland and they appeared on the woodland only on post-fire. The abundance was high in woodland than grassland habitat, but there was no significant difference between them. (U’, and .5601) The species like White bellied Canary and African Green Pigeon were observed only in the woodland before burning and they were not seen again after their habitat being burnt.
The species which appeared in post-fire included Red fronted Tinkerbird, Black bellied Starling, Grey backed Camaroptera, and Eastern violet Sunbird. Generally most species were not affected by burning, and they population did not seen to fluctuate following burning of their habitats.
WOODLAND HABITAT
There was total of 43 bird species found on this habitat in the entire time of collecting data, the day before burning contained, 55.81%, (23) of the total species found in the habitat, the first week after burning had 60.46%, (30), in the second week it was 90.69%, (41), the third week was 79.74%, (32) and for the fourth week it was 62.79%,(28), of the entire total species of the woodland habitat.
GRASSLAND HABITAT
The total number of species found was 18 for the entire time of collecting data, in the day before burning the abundance was 61.11%, (11), in the first week after burning was 50.00%, (09), the second week after burning was 72.22%, (13), in the third week was 72.22% (13), and on the fourth week was 66.66% (12) of the entire number of species found in the grassland habitat which was 18 birds.
DIVERSITY IN GRASSLAND
The number of species increased on post-fire for both types of habitats, and it reached at the peak on the second week after burning and then started to decrease again as the shoots were growing as shown in figure 2.
The number of birds was high in woodland than grassland habitat and they both responded positively by increase in post-fire weeks.
DISCUSSION
The study in two habitats revealed difference in abundance of birds between woodland and grasslands, and the abundance was higher in woodland habitat than the grassland habitat, this can be due to the richness in vegetations and plant species in woodland habitat which provides more refuge to the bird species as well as attracting other more species which can be used by birds as source of food. The grassland is open hence reduces ability of supporting large number of species of birds for habitat as well as other species which can be source of food. Cintra and Sanaiotti (2005) observed that, at the large spatial scale some bird species were more abundant post-fire passage. The apparent increase in some species occurred only in one area and may have been due to the drastically reduced cover and, therefore, greater visibility in that area of this ground-dwelling species. This may also be partially true for such arboreal frugivorous birds tend to increase regionally in abundance post-fire.
The woodland habitat was more diverse compared to grassland habitat, before and after burning, also burning did not have any significant effect to the diversity of bird species since the increase of bird species was only slice and hence not significant in both types of habitats.
The species which seen to be affected by burning were African Green Pigeon and White Bellied Canary, since they were present in the woodland habitat before burning and they were not seen during post-fire data collection. Some birds appeared on burned habitats and they were not present in unburnt time, most of these news species in a particular area appeared on the second and third week after burning when shoots were a little bit long. This might be due to the appearance of new nutritious part of plants which are essential for birds and the insects they feed on, since birds like Scimitar bills, Pied kingfisher and White throated bee-eater increased in number in post-fire areas. These was also observed by Lyon and Marzluff (1984), that fire had different effect on wildlife since some species were favoured over others as a result of changes in abundance of food covers.
Species like Rattling Cisticola, Black Backed Puffback, and bronze Mannikin were not affected by burning since they were found in both burnt and unburnt grassland habitats. Fire management can help maintain natural habitats, increase forage for wildlife, reduce fuel loads that might otherwise lead to catastrophic wildfire, and maintain natural succession. Today, there is an emerging challenge that fire managers need to be aware of: invasive species. (Cintra and Sanaiotti 2005).
From the results obtained from Mann Whitney U-test, the results showed significant difference in abundance of bird species, where by the woodland habitat was more abundant in bird species than in grassland habitat.
As shown in the figure 3, there was higher number of bird species in woodland habitat compared to the grassland habitat, since most of the bird species were found in woodland habitat and only few were species like Flappet lark, Senegal lapwing and Yellow throated longclaw, were found in grassland only.
Plants stressed through drought, disease, insect infestations, overgrazing, old age or a combination of these factors are likely to be negatively impacted by burning regardless of how they would respond if healthy (Bunting, 1985). However, trees that die as a result of fire can provide an important habitat component for certain species. In case of SANAPA, the study showed appearance of species like, black bellied starlings, violet Uluguru sunbird, laughing dove and crowned hornbill, their appearance in the study site followed after burning of the two habitats. (Appendix 1).
Habitat and community structure can include dead as well as living components. Large diameter logs provide habitat in the form of travel routes, as well as feeding, nesting, and reproduction. Snags are critical nesting and feeding habitat for many species of birds, as well as mammals and amphibians. Insectivorous birds that inhabit snags not only harvest insects in recently burned areas, but help regulate populations of insects in adjacent unburned areas, and in the newly developing forest (Neitro et al., 1985).
In the study in Saadani national park, the species of rattling cisticola did not seen to be affected by burning, since they were found in the study area before and after burning with their population standing steady. (Appendix 2)
CONCLUSION AND RECOMMENDATION
Basing on the results obtained in this study I would like to recommend the following things in future and in other studies; To carry out a study which will determine the causes of the decrease in birds species immediately after burning and their recovery in the second week after burning. Also what causes the decrease of the birds in the fourth week after burning. This can done by considering species of birds found in this area and their particular food types, and the relation between food types and fire.
Although some individuals may persist in recently burned areas by using remnant patches of habitat, many will be forced to relocate. Managers currently use a rotational system of burning that creates a mosaic of post fire vegetation types across Refuge grasslands. Thus, habitat loss is localized and species that are displaced by fire may find habitat in adjacent unburned areas, assuming it is unoccupied. Despite some short-term negative effects, we believe the continued use of spring burning will ultimately benefit open grassland species by removing some of the invasive shrub component and restoring areas of open grassland. However, until prescribed burns are conducted under conditions favo~ingm ore intense fires, these changes will be slow to develop. (Kirkpatrick et al., 2001).
An indirect effect of fire on bird community composition may also result from its negative impact on the invertebrate community. Fire can reduce significantly the abundance of some dung beetle (Scarabaeidae) species and some arboreal ant species (Cephalotes, Crematogaster, Azteca, Zacryptocerus, and Pseudomyrmex). Although birds do not usually feed on ants, the distribution and abundance of many other arthropods (spiders, caterpillars, butterflies, beetles) can be affected negatively by ant presence and abundance.
The timing of fires is also significant. Because most fire events start in the middle of the dry season when the majority of bird species begin breeding bird population recruitment could be affected negatively by a reduction both in safe nesting sites and food supplies. However, this possibility in the area studied has yet to be investigated (Sanaiotti & Cintra, 2005).