The taxonomy, distribution and ecology of centipedes of the genus Asanada (Scolopendromorpha:Scolopendridae) in Nigeria

The distribution and variation of Asanada spp. in Nigeria is described. Three forms are recognized and their relationship with other African populations of Asanada is discussed. An account of the biology of A. sokotrana in Nigeria is given. During the rainy season the species is characteristically found in deserted mounds of Trinervetermes spp. but disappears from this habitat in the dry season, presumably retreating into the soil. Egg-laying and brooding take place at the latter end of the dry season and the young appear at the beginning of the rains. Males live for only one year but some females live for longer than this. Growth continues through the dry season.     

Seasonal variation in patch use in a tropical African environment

We used giving-up densities (GUD) to study patch use decisions of small granivorous passerines throughout the year. We measured GUDs continuously in four sites for a period of 9–10 months per year during 2004 and 2005 in a savannah area in Jos, central Nigeria. The study thus covered a period from the middle of the dry season, through the wet season to the beginning of the next dry season in each year. We placed experimental food patches in both open areas and in cover to investigate possible effects of predation risk and thermal hazard on the foraging behavior of the birds. We found a difference in GUDs between the microhabitats, with a consistently lower GUD in cover throughout the year and for the two years. During both years GUDs followed a pattern coinciding with the seasonal change in local seed availability. An initial decline in GUDs late in the dry season was followed by a steady increase during and after the rains. A similar trend in GUDs observed for both years supports the conclusion that GUDs measure the feeding birds' assessment of environmental quality, possibly in combination with other factors changing predictably during the year. We conclude that food abundance may act with other environmental and ecological factors to affect foraging decisions throughout the year.     

NOTES ON THE BIRDS OF SOUTH-WESTERN NIGERIA.

Notes are based on a collection of 700 skins. Extensions of range include Trachylaemus p. togoensis, Prodotiscus i. flavodorscdis, Campethera n. nivosa, Bleda canicapilla, Phyllastreplms i. icterinus, Pedilorhynchus c. aximensis, Sylvia bnrin, Apalis c. caniceps, Macrosphenus concolor , and Spermophaga h. togoensis recorded from Nigeria and Apus c. strenbelii from West Africa for the first time.
Taxonomic points include reasons for regarding Centropus epomidis as a colour phase of Centropus senegalensis and Sylvietta flavixentris nigeriae as a synonym of Sylvietta flainventris.
Dates of breeding are given for many species, and nests and eggs arc described. Indicator indicator was found in the nest of Hirundo setnirufa.
The chick of Porphyrio alleni is described.     

The ghost of a recent invasion in the reduced feeding rates of spitting cobras during the dry season in a rainforest region of tropical Africa?

Two species of cobras (Naja melanoleuca and Naja nigricollis) are known to occur in south eastern Nigeria, where much of the pristine rainforest surface has been felled in the last thirty years, and where the actual landscape is generally constituted by a mosaic of farmlands, plantations, suburban areas, with a few remnant forest fragments. In this region, Naja nigricollis is currently extending its range, especially by exploiting recently deforested areas. Based on the known general distribution range of this species and on the available literature data, it appears that Naja nigricollis has been colonizing the forested region of south eastern Nigeria, starting from the relatively arid savannas of central Nigeria, where this species aestivates during the driest months. In the forest region, however, snakes do not need to aestivate during the dry season. Nevertheless, whereas Naja melanoleuca has a foraging activity extended all-the-year round, Naja nigricollis reduces feeding rates during the dry months, although it does not suspend above-ground activity in these months. I suggest that rainforest spitting cobras suspend feeding during the dry months because their behaviour is just a ‘ghost’ of their recent past, when they were ‘normal’ spitting cobras of dry savana regions, which were thus constrained to aestivate during the dry season as it is the rule in this species in central and northern Nigeria. The ‘gost-of-the-past hypothesis’ seems to fit well with the ‘invading’ presence of Naja nigricollis in Nigerian areas where they were reported as rare or, even, absent, up to a few decades ago. Other hypotheses are discussed, and rejected.     

Environmental control of flowering periodicity in Costa Rican and Mexican tropical dry forests

Aim We analyse the proximate causes of the large variation in flowering periodicity among four tropical dry forests (TDF) and ask whether climatic periodicity or biotic interactions are the ultimate causes of flowering periodicity. Location The four TDFs in Guanacaste (Costa Rica), Yucatan, Jalisco and Sonora (Mexico) are characterized by a 5–7 month long dry season and are located along a gradient of increasing latitude (10–30°N). Methods To dissect the differences in flowering periodicity observed at the community level, individual tree species were assigned to ‘flowering types’, i.e. groups of species with characteristic flowering periods determined by similar combinations of environmental flowering cues and vegetative phenology. Results Large variation in the fraction of species and flowering types blooming during the dry and wet season, respectively, indicates large differences in the severity of seasonal drought among the four forests. In the dry upland forests of Jalisco, flowering of leafless trees remains suppressed during severe seasonal drought and is triggered by the first rains of the wet season. In the other forests, leaf shedding, exceptional rainfall or increasing daylength cause flowering of many deciduous species at various times during the dry season, well before the summer rains. The fraction of deciduous species leafing out during the summer rains and flowering when leafless during the dry season is largest in the Sonoran TDF. Main conclusions In many wide‐ranging species the phenotypic plasticity of flowering periodicity is large. The distinct temporal separation of spring flowering on leafless shoots and subsequent summer flushing represents a unique adaptation of tree development to climates with a relatively short rainy season and a long dry season. Seasonal variation in rainfall and soil water availability apparently constitutes not only the proximate, but also the ultimate cause of flowering periodicity, which is unlikely to have evolved in response to biotic adaptive pressures.     

Seasonal variation in the protein content and the grazing of some tropical savanna grasses

This paper presents the effects of seasonal variation on the protein contents of four grass species examined in the experimental fire plots at Kainji Lake National Park in the Northern Guinea savanna zone of Nigeria. Also reported is the proportion of grass utilized on year-long basis. Tropical savanna grasses generally have higher protein contents at the beginning of the growing season than at the end when they become tall, coarse and unpalatable. It is also shown that the percentage of grass species utilized by game follow the seasonal changes in their protein contents; utilization being highest when the protein content of grass is optimum. It is stressed that trees, shrubs and forbs should not be totally eliminated from grazing lands because of the great contribution they make to animal feeding during the dry season when the grasses become dry and coarse with low nutritive value.     

Biannual breeding and moult-breeding overlap of the Chestnut-bellied Starling Spreo pulcher

At Kano, Nigeria, the Chestnut-bellied Starling Spreo pulcher has two distinct breeding seasons, a long one from the late dry season to the early rains (February to June) and a short one in September, October and rarely November following the rains. Males have enlarged testes from February to October, so the breeding periods are probably determined by the reproductive condition of the females. Most individuals breed in both periods but some breed only in the pre-rains period. Adult wing-moult begins in March and April, overlapping with any breeding attempts in the latter half of the pre-rains session; some birds continue to moult into the post-rains session. Post-juvenal wing-moult is from August to January for birds reared in the previous pre-rains period and is simultaneous with adult moult for birds reared in the post-rains period. An increase in ambient temperature may be the most important proximate cue determining the pre-rains and also the post-rains breeding periods. A correlation between moult-breeding overlap and co-operative breeding for some tropical birds is suggested and discussed briefly.     

Leaf flushing phenology and herbivory in a tropical dry deciduous forest,southern India

Patterns of leaf-flushing phenology of trees in relation to insect herbivore damage were studied at two sites in a seasonal tropical dry forest in Mudumalai, southern India, from April 1988 to August 1990. At both sites the trees began to flush leaves during the dry season, reaching a peak leaf-flushing phase before the onset of rains. Herbivorous insects emerged with the rains and attained a peak biomass during the wet months. Trees that flushed leaves later in the season suffered significantly higher damage by insects compared to those that flushed early or in synchrony during the peak flushing phase. Species whose leaves were endowed with physical defenses such as waxes suffered less damage than those not possessing such defenses. There was a positive association between the abundance of a species and leaf damage levels. These observations indicate that herbivory may have played a major role in moulding leaf flushing phenology in trees of the seasonal tropics.     

Food and feeding ecology of the rock fowl Picatthartes oreas in Old Oyo National Park, Nigeria

The rock fowl is an endangered species and its food and feeding ecology was studied in the forest zone of Old Oyo National Park, Nigeria. The methods used were direct observation, and fragmentation analysis of faecal and crop content of samples collected during both the wet and dry seasons. The results showed that rock fowl feed on a wide range of species of insects, fruits and flower buds. In the wet season, animal resources represented 54 and 62% of the adult and chick diet, respectively, whereas in the dry season, animal food resources represented about 60% of both adult and the chick diets. There was a significant difference (P < 0.05) in the food composition of the birds between the dry and wet seasons. There was also a significant (P < 0.05) difference in food preference between adults and chicks. Food sharing was not common, although it was observed between rock fowl cockerels and hens. Food search and selection indices were directly related to season and food availability. It was concluded that food scarcity may not be a serious contributory factor in the threat to the rock fowl.     

AFRICAN MIGRANTS IN NIGERIA

Owing to the regular alternation of wet and dry seasons and to the relatively simple arrangement of vegetation zones, migration is a well-developed phenomenon in the northern tropics of Africa. Nigeria is well placed for its study. While a vast amount remains to be learned, a systematic treatment of the 672 Nigerian bird species shows that at least 126 of them are migrant. Species newly shown to be migratory include the sunbird Nectarinia pulchella, the bunting Fringillaria (Emberiza) tahapisi, and the sparrow Gymnoris (Petronia) dentata, and corroborative evidence is adduced for many more. New interpretations are placed on the movements of the bustard Neotis denhami, the Painted Snipe Rostratula benghalensis, and other species. Most families that are migrant in the temperate zone (e.g. storks, cuckoos, nightjars, hirundines) have several migrants among their tropical representatives, except flycatchers, thrushes, warblers and shrikes. Important tropical migrant families include the kingfishers and sunbirds. The following ecological correlates emerge: migration appears to be more important at lower than higher trophic levels in the ecosystem; only one primary lowland rain forest and one montane forest species migrate; 95% of African migrants in Nigeria inhabit the five savanna zones, where the 120 migrants comprise 28% of the avifauna; most savanna migrants cross one, two or three vegetation zone boundaries; few are restricted within a single zone or cross four boundaries; twice as many savanna species are eurytopic (habitat-tolerant) as stenotopic (habitat-tied), and twice the proportion of eurytopic as stenotopic species are migrant; the majority of migrants move so as to avoid the winter drought in northern Nigeria (insectivores being little affected) and also the heaviest summer rains in southern savannas; migration is initiated by climatic factors such as rains, dry desert winds, etc. Three to six Nigerian species cross the Equator, but the stork Anastomus lamelligerus is shown to breed in Nigeria and the Chad basin and may not be a trans-equatorial migrant. A quail, a crake, a coucal and five cuckoos have space-time distribution patterns (motograms) in Nigeria that suggest equatorial migration. Motograms figured for 60 species show great variation. Nearly all land-bird migrants move with the progression of the sun and the inter-tropical front, north in spring and south in autumn. The basic pattern is thus a summer wet-season range at higher latitude than the winter dry-season range, and specific patterns vary according to the absolute and relative latitudinal limits af each season, and to speed and dates of migration. Comparison of congeneric migrants having different breeding seasons or motogram patterns suggests that a specific migration pattern is fixed by ecological necessity, and reproduction occurs at that time in the year when the species is stationary longest. Breeding seasons may span migration periods, leading to two-stage early-rains migration in e.g. the kingfisher Halcyon leucocephala. Water-bird migrations are complicated by opportunist breeding and responses to floods and changing water levels in rivers. A few species move with the typical land-bird pattern; others concentrate at perennial marshes in arid northern savannas, and may disperse in all directions from the few west African breeding stations.     

Irregular rain cues and the germination and seedling survival of a Panamanian shrub (Hybanthus prunifolius)

Summary Seeds of the Panamanian shrub, Hybanthus prunifolius (Schult.) Schulze (Violaceae) are dispersed at different times in different years ((March to June) and are exposed to the irregular rainfall of the dry season in some years. Fluctuations in soil moisture in the dry season represent suboptimal conditions for germination and seedling survival. There are no mechanisms to prevent germination prior to the arrival of consistent rains in the wet season.Among three natural cohorts of seeds followed in two years, the cohort experiencing the longest time from sowing to consistent rains had the highest germination, but it also had the longest time lag from sowing to, beginning of germination, longest germination period, and lowest survival of seedlings 3 months after sowing.Seeds were also induced experimentally to germinate under 14 different moisture patterns. The patterns encompassed 1) varying lengths of moisture before a dry period, 2) inconsistent moisture, and 3) varying lengths of dryness prior to any moisture.Mortality of seeds by fungal infection occurred if the wet period was delayed. But germination was less affected by fluctuations than was seedling survival. Length of the first wet period and frequency of occurrence of the wet period both affected germination levels. Survival and development of seedlings was influenced by the number of days exposed to dry conditions and by the stage of development at the beginning of the dry period. Young seedlings suffered attrition due to drought stress, and older seedlings died from fungal attack.Results from field and experimental sowing of seeds both indicate that this perennial species has minimal defense against germination when conditions are suboptimal for seedling survival. Undoubtedly there is more recruitment in some years than in others.     

Ontogenetic diet shifts in Roeboides affinis with morphological comparisons

Fishes of the characid genus Roeboides are documented as lepidophagous, but the degree of specialization on scales varies between species. This study examines ontogenetic changes in morphology and diet of Roeboides dayi and Roeboides affinis from Venezuela. Juveniles of both species feed on microcrustacea and insects during the wet season, when availability of these resources is greatest. As aquatic habitat decreases during the dry season, insect and microcrustacea availability decreases and fish densities increase. As the fish densities increase, scale consumption becomes more profitable. Interspecific differences in the degree of specialization of the teeth and jaws was associated with the degree of scale feeding. Adult R. dayi consumed scales in approximately equal proportions to insects. Adult R. affinis consumes approximately 100% scales, and has more specialized head morphology than R. dayi.     

FACTORS AFFECTING THE FOOD SUPPLY AND BREEDING SEASON OF RESIDENT BIRDS AND MOVEMENTS OF PALAEARCTIC MIGRANTS IN A TROPICAL AFRICAN SAVANNAH

The fact that Palaearctic migrants arrive in the northern tropical savannah of Africa during the dry season suggests potential competition for food with African species. Moreover, in the southern tropical savannah African species breed during the rainy seasons, when Palaearctic migrants are present. In the equatorial area of Serengeti, East Africa, an index of the food supply for insectivorous birds was obtained from 3 years of light-trap measurements and sweep net samples. Adults of Lepidoptera, Coleoptera, Orthoptera and Isoptera are sparse in the dry season but become locally abundant after the first rainstorms that mark its close. They are apparently blown by converging winds ahead of the inter-tropical front and settle to lay eggs where rain has fallen. These early storms therefore produce localized superabundances of food. In the ensuing rainy seasons insect abundance remains high. African insectivorous birds breed during the wet period, reaching a peak two months after the insect increase. It is suggested that this lag is due to the need to recover body condition, build up reserves for eggs, develop gonads and wait for vegetation and insect larvae to develop. In the samples available, breeding records of above-ground nesters peaked in the first rains, while ground-nesters peaked in the second (main) rains. Predators bred towards the end of the rains, when there is an abundance of fledglings and small mammals. Thus the food supply could act as the ultimate factor determining the timing of the breeding season in this area. Palaearctic migrants arrive in the Serengeti 4–10 weeks ahead of the main rain front. However, most species are only found where rain has fallen recently. When conditions dry up they move on to other wet areas. Thus they overlap with African species only where there is a superabundance of insects. When the rains become widespread Palaearctic migrants disperse into their usual habitats, and therefore appear not to compete for available resources with closely related species of African birds. The situation in West Africa, where residents and migrants overlap throughout the dry season, cannot be explained in the same terms.     

Dietary and dental variations in the genus Lemur, with comments concerning dietary-dental correlations among Malagasy primates.

Field studies of feeding in the lemur subspecies Lemur fulvus rufus and L. f. mayottensis have revealed that feeding patterns within a single species can be markedly different, both regionally and seasonally. Thus L. f. rufus is a dietary specialist (3 plant species accounting for 80-90% of feeding time), and is highly folivorous, especially during the dry season (90% of feeding time spent eating leaves during the dry season, and 53% during the wet season). On the other hand, L. f. mayottensis is more generalized dietarily (the parts of 12 plant species accounting for 90% of feeding time), and is primarily frugivorous (64% of feeding time spent eating fruit, with a monthly maximum during the wet season of 79%. In both these respects, L. f. mayottensis resembles L. catta are more closely thant it does L. f. rufus. When size differences are corrected for, Lemur fulvus rufus has significantly longer second lower molar shearing crests than does L. f. mayottensis. Other folivorous Malagasy strepsirhines also tend to have long shearing crests than frugivorous forms. Some data on cheirogaleines also suggest that the more insectivorous species have better developed molar crests than frugivorous species. Some apparent exceptions to this pattern are noted, especially for Lemur catta, which in certain functional respects dentally more closely resembles L. f. rufus than L. f. mayottensis. The problems of dietary classifications are discussed.     

Seed Dynamics in Relation to Gaps in a Tropical Montane Rainforest of Hainan Island, South China： （I） Seed Rain

Seed dynamics is an important part of stand dynamics in forest ecosystems. In this paper, 26 gaps were randomly selected to study the influence of gaps on the spatial and temporal patterns of seed rains in a tropical montane rainforest of Hainan Island, South China. Three zones for each gap, including outside gap zone （Non-gap）, transitional gap zone （EG-CG）, and central gap zone （CG）, were designed, and fourseed traps （each lm x lm in size） were placed in each zone. Seed rains were collected by these traps every 10 days from June 2001 to May 2002. Seed rain varied greatly with season and generally exhibited a pattern of unimodal change during the study period： seed abundance and species richness were both greater in the wet season than in the dry season. Gaps significantly influenced the temporal patterns of both species richness and density of seed rains. Gaps had no significant influences on the spatial distribution patterns of seed rain species richness, but significantly affected the spatial distribution pattern of seed rain densities. Among the three different zones of gaps, the outside gap zone generally received more seeds inputs than the two other gap zones.     

Dynamics in the length-weight parameters of the mudskipperPeriophthalmus barbarus (Gobiidae), in Imo River estuary, Nigeria

Seasonal and intersexual dynamics in parameters of the length-weight relationship of the mudskipperPeriophthalmus barbarus, from Imo River estuary, Nigeria, were studied. The proportionality constant or intercept (a) was aseasonal in males, but in females it was significantly higher in the dry season (November–April) than during the rains (May–October) due to heightened breeding activity. The length exponent (b) depicted seasonal isometry in males. In females, isometry was evident in the dry season while a positive allometry occurred during the wet season. The sizes of the smallest and largest specimens examined did not regulate variations in the magnitudes of (a) and (b) in both sexes. The insignificant intersexual variation in the length-weight parameters suggests the possibility of using a single predictive length-weight equation for the population. However, the sexes exhibited different monthly rank-orders of (a) and (b), thus making such composite estimates unreliable for a study spanning up to a year. Values of (a) and (b) were inversely correlated in both sexes. The population dynamics implications of the results are discussed.     

The food habits of wild ungulates in Uganda by analyses of stomach contents

Food eaten by six species of ungulates was studied by analysing stomach contents, using the method developed for faecal analyses. Frequency analyses showed that some herbivore species tend to be selective in their feeding. This suggested that availability and growth form of plants may be important in this respect. The observations agreed with those of other workers, which shows that feeding habits are consistent over large areas. In general, herbivores were classified in three groups with regard to preferences; namely pigs, certain antelope, and buffalo and waterbuck. Comparison of the proportions of epidermal fragments of particular grass species present in stomachs in wet and dry seasons showed that significant seasonal differences exist in the diet of most herbivores. Annuals and most members of the Andropogoneae were present in stomachs in larger proportions during the rains for reasons of availability and palatability. Chloris gayana and Sporobolus pyramidalis were usually present in greater proportions in dry seasons. Differences in the proportions of epidermal fragments of particular plant species present within wet or dry seasons were usually insignificant. A few herbivores, however, showed significant differences within seasons. This indicates that they are sensitive to small changes in plants and that they may have a feeding cycle involving a gradual and regular alternation of plant species. A comparison of the proportions of fragments of the same plant species in different herbivores showed that animal species usually avoided competition by their specialized food habits. There was greater separation in the longer dry season, but competition may have occurred when food supplies were reduced by large herbivores such as buffalo and hippopotamus.     

Reproduction in the agile wallaby Macropus agilis (Gould) in the tropical lowlands of the Northern Territory: opportunism in a seasonal environment

The agile wallaby, Macropus agilis, abounds on the tropical lowlands of the Northern Territory (12° 30′-13°S). The climate is markedly monsoonal and has an annual mean rainfall of 135 cm. During the rainy season, much of the wallaby's major habitat, the extensive coastal plains adjacent to the rivers, becomes flooded. The agile wallaby breeds continuously in captivity but not necessarily so in the wild, although fecundity was very high indeed. Reproduction was more successful on fertilized, nitrogenous pastures of farmland than on grasses of lower nutritive value. Breeding declined least (5%) in the dry season droughts as pastures dwindled and dried out, and most (> 45% in one year) during the rainy season in bushland where the dry season feeding grounds were inundated. The more quickly that the open riverine plains were flooded after the rains began, the higher the loss of breeding and the mortality of pouch-young. The mortality rates of young were similar on both improved and native pastures, however, with only about 35% of new-born surviving to 7 months in the pouch. Wallabies on the improved pastures were at higher densities than on the native pastures which may have influenced that mortality. That females became anoestrous during pregnancy, subsequently gave birth but did not have the usual post-partum oestrus makes the agile wallaby similar to the desert red kangaroo, M. rufus, in its method of entering anoestrus. Also as in that species, anoestrous lactating females can return to oestrus later. The agile wallaby is only the second macropodid marsupial for which these adaptations have been described. Such an adaptation in a desert species has a clear reproductive advantage which is not obvious in this tropical macropodid. Unlike the agile wallaby, the Asiatic waterbuffalo, (Babulis babulus) and domestic cattle, (Bostaurus and B. indicus) which have been introduced to its range breed and give birth on the rains. Such is the reproductive pattern in the tropical ruminants of East Africa also. Seasonal breeding is phylogenetically possible in macropodid marsupials because southern species. M fuliginosus, M. Eugenii, M. r. rufogriseus and Setonix brachyunis, do so in the mediterranean environment there. They time their breeding so that young leave the pouch when pastures are flush after the winter rains. The suggested reason for these differences in breeding of macropodids is seasonal unpredictability. Despite the enormous difference in rainfalls, weekly variability in pasture growth throughout the year is actually the same in monsoonal northern Australia as in the desert, and greater than in southern Australia. Environmental unpredictability may therefore be as important as the overall level of pasture growth in determining reproductive strategies of macropodid marsupials. For the tropical agile wallaby, the unpredictability can cause an absolute shortage or absolute abundance of food in the usual dry season depending on the length of the rainy season and on unseasonal cyclonic weather. It can also cause a relative shortage of food in the rainy season due to flooding of the best feeding grounds. It is concluded that reproduction in the wild mainly depends on the quantity and quality of the food supply.     

Do seasonal changes in light availability influence the inverse leafing phenology of the neotropical dry forest understory shrub Bonellia nervosa (Theophrastaceae)?

In tropical dry forests most plants are deciduous during the dry season and flush leaves with the onset of the rains. In Costa Rica, the only species displaying the opposite pattern is Bonellia nervosa. To determine if seasonal changes in light availability are associated with the leaf and reproductive phenology of this species, we monitored leaf production, survival, and life span, as well as flower and fruit production from April 2000 to October 2001 in Santa Rosa National Park. Leaf flushing and flower bud production took place shortly after the autumnal equinox when day length starts to decrease. Leaves began expansion at the end of the wet season, and plants reached 70 % of their maximum leaf area at the beginning of the dry season, maintaining their foliage throughout the entire dry period. Leaf shedding occurred gradually during the first three months of the wet season. Leaf flushing and shedding showed high synchrony, with leaf numbers being related to light availability. Maximum leaf production coincided with peaks in radiation during the middle of the dry season. Decreasing day length induces highly synchronous flower bud emergence in dry forest species, but this is the first study indicating induction of leaf flushing by declining day length.