Late Dry Season Research Articles

Fire management business in Australia's tropical savannas: Lighting the way for a new ecosystem services model for the north?

Fire management business in Australia's tropical savannas: Lighting the way for a new ecosystem services model for the north?

Effect of season on structural composition of drake testes and daily spermatozoa production as determined by quantitative testicular histology

Seasonal effects on the structural features of drake testes and daily spermatozoa production were investigated by a light microscopy technique, as well as morphometric and quantitative histological procedures. The present study is aimed at understanding the effects of different seasons on the reproductive potential of drakes. The results showed that the volume of the testes occupied by seminiferous tubules was similar (P>0.05) in all the seasons studied. However, the relative percentage of the primary spermatocytes, spermatids, spermatozoa, epithelial height, lumen diameter, and Leydig cells were significantly higher (p<0.05) during the early and late rainy seasons compared to the early and late dry seasons. The daily sperm production per testis in the early rainy season, late rainy season, early dry season, and late dry season were 0.86 × 109± 1.30, 0.84 × 109± 1.20, 0.54 × 109± 1.13 and 0.52 × 109± 1.17, respectively. The daily sperm productions per testis and per gram of testes were significantly higher (p<0.05) during the early rainy season compared to the early and late dry seasons, respectively. All the micrographs examined, showed evidence of normal spermatogenesis throughout the year. The findings in the present study indicate that drakes in the tropical environment (south-eastern Nigeria) are capable of breeding throughout the year; however, sperm production efficiency is optimal during the early rainy season.

Status of the Endangered Yellow Chat Epthianura crocea tunneyi on the western South Alligator River floodplain, Kakadu National Park

The current status of the Endangered Yellow Chat Alligator Rivers subspecies Epthianura crocea tunneyi is poorly known. A survey of Kakadu National Park floodplains, Northern Territory, in 2004 identified the western floodplain of the South Alligator River as a key population area. To provide preliminary information on the status of the subspecies in Kakadu National Park, this floodplain was intensively surveyed over a 4-day period in September 2014 and compared with the 2004 survey, which was undertaken at a similar time of year (late dry season: October–November). Despite covering considerable areas of floodplain habitat over nearly 40 hours of surveying, Yellow Chats were recorded in only one area in 2014; 27 Yellow Chats from nine observations were recorded over 2 days, with a minimum number of 17 individual birds (16 adult and 1 juvenile) observed. This compared with a total of 65 Yellow Chats from 2 days of surveying in 2004, clustered around five areas of the western floodplain of the South Alligator River. Habitat in 2014 comprised predominantly dry floodplain lagoon, consistent with previous surveys. Feral animals (in particular Feral Pigs Sus scrofa ) were regularly observed throughout the surveys, as was significant feral-animal damage to wet floodplain areas. Although these results suggest a possible decline on the western South Alligator River floodplain over a 10-year period, a comprehensive survey is required of all floodplains within the subspecies’ range to assess overall population status. This could inform the establishment of annual monitoring sites in order to evaluate long-term population trends, essential data for management of threatened species.

Prevalence and Seasonal Variation of Parasitic Diseases in Dogs Presented at Small Animal Clinic of Veterinary Teaching Hospital, University of Ibadan, Ibadan, Nigeria Between 2001 And 2005

Abstract A retrospective study of data from clinical records at veterinary teaching hospital, university of Ibadan was undertaken to determine the prevalence and seasonal variation of parasitic diseases diagnosed in dogs, between 2001 and 2005. The data generated were analyzed demographically using descriptive statistics. Out of the 753 cases examined within the study period, helminthosis had the highest occurrence of 470 (62.4%) followed by piroplasmosis, Ticks, mange, myiasis, Erhlichiosis, intestinal protozoa, Trypanosomiasis and Dermatomycosis with 100(13.3%), 99(13.1%), 49(6.5%), 15(2%), 11(1.5%), 4(0.5%), 4(0.5%) and 1(0.1%) number of cases respectively. Based on seasons, late dry season had the highest occurrence of 213 (28.3%) followed by early dry season with 203 (27%), late rainy season with 175 (23.2%) and early rainy season with 162 (21.5%). Based on years, 2005 had the highest occurrence of 267 (35.5%) followed by 2004 with 165 (21.9%) and 2003 with 130 (17.3%). The year 2001 and 2002 had the lowest occurrence of 97 (12.9%) and 94 (12.5%) respectively. The higher prevalence during dry season could be due to the environmental stress experienced during the period which might exert a negative influence on the immune system of the host, thereby increasing the likelihood for infection. Sensitization and Education of dog owners on preventive measures is vital in curbing some of these parasitic health problems. Keywords: Parasitic diseases, season, dog, prevalence

Species Composition and Relative Abundance of Insects of Veterinary Importance at Abuja, Nigeria

The insect fauna of University of Abuja was sampled with unbaited Bioconica and Nitsetrap from Oct. 19 to Nov. 30, 2012 (early dry season) and from Feb. x to Mar. y, 2013 (late dry season) to determine the occurrence and prevalence of insect species of veterinary importance. Efficiencies of the two traps were compared using the Student’s t statistic at tn = 0.05. Thirteen insect species in eight Families and five Orders were caught in the early dry season compared with seven species in five Families and two Orders in the late dry season. The Order Diptera had the highest representation (six Families) and the most abundant species was Stomoxys calcitrans (57.6 and 57.2 % of the total collections in early and late dry season, respectively); other dipterous species collected were Tabanus, Stomoxys, Chrysops Culicoides. Overall, Bioconical trap was more efficient than Nitse trap (x vs. y trapped insects, to.< 0.05). The roles of the dipterous insects in disease transmission and the repercussions to both man and livestock were discussed. The use of traps as a method of controlling insect population( s) and proper methods of waste disposal were recommended to evade health hazards linked to these insects.

Diurnal variability and biogeochemical reactivity of mercury species in an extreme high-altitude lake ecosystem of the Bolivian Altiplano.

Methylation and demethylation represent major transformation pathways regulating the net production of methylmercury (MMHg). Very few studies have documented Hg reactivity and transformation in extreme high-altitude lake ecosystems. Mercury (Hg) species concentrations (IHg, MMHg, Hg°, and DMHg) and in situ Hg methylation (M) and MMHg demethylation (D) potentials were determined in water, sediment, floating organic aggregates, and periphyton compartments of a shallow productive Lake of the Bolivian Altiplano (Uru Uru Lake, 3686 m). Samples were collected during late dry season (October 2010) and late wet season (May 2011) at a north (NS) and a south (SS) site of the lake, respectively. Mercury species concentrations exhibited significant diurnal variability as influenced by the strong diurnal biogeochemical gradients. Particularly high methylated mercury concentrations (0.2 to 4.5 ng L(-1) for MMHgT) were determined in the water column evidencing important Hg methylation in this ecosystem. Methylation and D potentials range were, respectively, <0.1-16.5 and <0.2-68.3 % day(-1) and were highly variable among compartments of the lake, but always higher during the dry season. Net Hg M indicates that the influence of urban and mining effluent (NS) promotes MMHg production in both water (up to 0.45 ng MMHg L(-1) day(-1)) and sediment compartments (2.0 to 19.7 ng MMHg g(-1) day(-1)). While the sediment compartment appears to represent a major source of MMHg in this shallow ecosystem, floating organic aggregates (dry season, SS) and Totora's periphyton (wet season, NS) were found to act as a significant source (5.8 ng MMHg g(-1) day(-1)) and a sink (-2.1 ng MMHg g(-1) day(-1)) of MMHg, respectively. This work demonstrates that high-altitude productive lake ecosystems can promote MMHg formation in various compartments supporting recent observations of high Hg contents in fish and water birds.

Deriving Multiple Benefits from Carbon Market-Based Savanna Fire Management: An Australian Example.

Carbon markets afford potentially useful opportunities for supporting socially and environmentally sustainable land management programs but, to date, have been little applied in globally significant fire-prone savanna settings. While fire is intrinsic to regulating the composition, structure and dynamics of savanna systems, in north Australian savannas frequent and extensive late dry season wildfires incur significant environmental, production and social impacts. Here we assess the potential of market-based savanna burning greenhouse gas emissions abatement and allied carbon biosequestration projects to deliver compatible environmental and broader socio-economic benefits in a highly biodiverse north Australian setting.Drawing on extensive regional ecological knowledge of fire regime effects on fire-vulnerable taxa and communities, we compare three fire regime metrics (seasonal fire frequency, proportion of long-unburnt vegetation, fire patch-size distribution) over a 15-year period for three national parks with an indigenously (Aboriginal) owned and managed market-based emissions abatement enterprise. Our assessment indicates improved fire management outcomes under the emissions abatement program, and mostly little change or declining outcomes on the parks. We attribute improved outcomes and putative biodiversity benefits under the abatement program to enhanced strategic management made possible by the market-based mitigation arrangement.For these same sites we estimate quanta of carbon credits that could be delivered under realistic enhanced fire management practice, using currently available and developing accredited Australian savanna burning accounting methods. We conclude that, in appropriate situations, market-based savanna burning activities can provide transformative climate change mitigation, ecosystem health, and community benefits in northern Australia, and, despite significant challenges, potentially in other fire-prone savanna settings.

Spatial overlap between sympatric wild and domestic herbivores links to resource gradients

In this study, we investigated the relationship between resource gradients and overlap between wild and domestic herbivores in a southern African ecosystem. We used an Enhanced Vegetation Index (EVI) to identify and test the presence of resource gradients i.e. vegetation greenness between agricultural areas and conservation areas in Southeastern Zimbabwe, part of the Great Limpopo Transfrontier Conservation Area. We then tested whether these resource gradients coincide with GPS collared cattle (Bos taurus) movements into wildlife areas, as well as drive spatial overlaps between cattle and the GPS collared African buffalo (Syncerus caffer). Results showed that resource gradients although variable, exist between the conservation area and surrounding agricultural area. Cattle used the conservation area less than expected during the dry season when vegetation greenness in the communal land was relatively lower than in the conservation area. Significant spatial segregation between cattle and buffalo occurred during the wet season and late dry season, while spatial aggregation occurred during the early dry season. Intensity of habitat overlap between cattle and buffalo during the early dry season was relatively high in habitats preferred by both species. Our results suggest that cattle movement into conservation areas is linked to resource gradients.

Winter breeding of a subtropical rainforest passerine: spatio-temporal distribution of prey and the sex-related foraging behaviour of the Southern Logrunner, Orthonyx temminckii

Most birds breed when food availability is at a maximum. The Logrunner Orthonyx temminckii, a ground-dwelling subtropical insectivore, breeds during the winter-dry season, when its invertebrate prey is believed to be least abundant. We investigated the spatio-temporal distribution of leaf-litter invertebrates and linked this to the foraging ecology and breeding of Logrunners. Fortnightly leaf-litter invertebrate samples revealed that the biomass of Logrunner prey did not vary significantly between the late-wet, early-dry and late-dry seasons, or between three microhabitats—forest interior, treefall gaps and gap edges. Further, the biomass of insect larvae, a nutritious and easily handled food source for young birds, remained constant through egg laying, hatching and fledging. During the dry winter Logrunner breeding season, the rainforest leaf litter may retain moisture and provide thermal insulation, thereby maintaining suitable habitat for invertebrate populations. Whereas invertebrate biomass remained stable during the breeding season, Logrunner foraging rates increased, presumably to increase calorific intake. Although not feeding nestlings directly, males provisioned females away from the nest. Therefore, we suggest that an interplay of several drivers has led to the evolution of winter breeding in these ground-foraging rainforest passerines. Although longer term investigations are required to determine whether their food source is more consistent in winter than summer, our data show that winter breeding coincided with the ready availability of nutritious, high calorie, leaf-litter invertebrates. This would enable Logrunners to rear chicks at a time that is usually considered inimical to these purposes.

Strategies in nitrogen uptake and use by deciduous and evergreen woody species in a seasonally dry sandhill community

Dry seasonal ecosystems such as the Florida sandhill are defined by a pronounced and consistent dry season that results in both water and nutrient limitation. Deciduous and evergreen species have evolved different leaf phenologies, which change the temporal pattern of nutrient demands for leaf growth. To measure N uptake for deciduous and evergreen species during late dry season deciduous leaf-out, we labeled the shallow soil with 15N by spreading a mixture of native sand and 15N-KNO3 around each tree and measured foliar nitrogen isotopic composition. We also measured foliar N content and nitrogen resorption efficiency (NRE). Evergreen and deciduous species were not consistently different in foliar N content and NRE, but natural foliar δ15N values were consistently higher in deciduous species. Labeling experiments show that uptake rate of 15N- labeled NO3 − was lowest for the deciduous species. Inconsistent results in foliar N content and NRE do not explain the differences in leaf habit in nutrient-poor ecosystems. Low N uptake during leaf-out limits deciduous species to the most fertile regions of the Florida scrub as well as in several other ecosystems, so that they can take up sufficient N to meet the demands of leaf growth.

Impacts of oil palm agriculture on phyllostomid bat assemblages

Rising global demand for palm oil comes mainly at the expense of tropical forests, and palm plantations are increasing steadily in Latin America. Conversion of forest to oil palm agriculture accelerates biodiversity loss by dramatically altering availability and abundance of resources. Assessing the impact of these monocultures on highly diverse keystone groups such as bats is of particular ecological and economic importance. We compared phyllostomid bat assemblages in mature lowland forest interior, at forest margins and within oil palm plantations in southwestern Costa Rica. A total of 45 mist-netting nights in the late dry season yielded 1235 individual captures from 31 species. Bat assemblages in oil palm plantations were clearly distinct from those at forest sites and exhibited lower species richness, similar to results reported for Southeast Asia. Assemblage structure within oil palm plantations was characterized by increased relative abundance of common frugivorous Stenodermatinae and the loss of rare species, mainly disturbance-sensitive animalivorous Phyllostominae. Although plantations may serve as flyways for highly mobile matrix-tolerant species, even small oil palm plantations seem to act as effective barriers for many others, particularly understory gleaning animalivores. By decreasing landscape permeability even for highly mobile animals such as bats, oil palm agriculture may consequently reduce population connectivity and foster faunal impoverishment, which in turn can diminish crucial ecosystem services provided by bats. The advancing expansion of these monocultures in Latin America calls for appropriate precautionary conservation measures to protect and preserve biodiversity in oil palm growing countries.

Modeling vegetation and wind erosion from a millet field and from a rangeland: Two Sahelian case studies

Quantifying wind erosion and dust emissions in the semi-arid Sahel remains challenging because of the large seasonal and interannual dynamics of surface properties. The increasing conversion of rangelands into croplands raises issues for quantifying wind erosion over these two contrasted surfaces. Whereas wind erosion models have been so far applied to these two surface types separately, this study proposes a common modeling approach to represent the horizontal flux from Sahelian rangelands and croplands. Pair simulations of both typical Sahelian land surface types investigate the horizontal flux due to wind erosion over a 3-year period for two instrumented sites in Mali and Niger. Two different vegetation models simulate the specific phenology and growth of a rangeland grass and a millet crop. These models also account for the local cropping and pastoral practices. Compared to field measurements, the vegetation cover is satisfyingly simulated by the models, especially the strong seasonal dynamics. Specific parameterizations of the aerodynamic surface roughness length (Z(0)) as a function of vegetation variables are established using measurements from the two sites. The simulated horizontal flux turns out to be higher for a cropland than for a rangeland by approximately a factor 1.5, implying that increasing Sahelian cropped areas would increase dust emissions from the Sahel. This difference is mainly due to the time shift between grass and millet growth: the latter starts growing about 2-3 weeks later than annual grass. The amount of dry vegetation remaining during late dry season is also important for Sahelian wind erosion.

Study of aerosol optical properties at Kunming in southwest China and long-range transport of biomass burning aerosols from North Burma

Seasonal variation of aerosol optical properties and dominant aerosol types at Kunming (KM), an urban site in southwest China, is characterized. Substantial influences of the hygroscopic growth and long-range transport of biomass burning (BB) aerosols on aerosol optical properties at KM are revealed. These results are derived from a detailed analysis of (a) aerosol optical properties (e.g. aerosol optical depth (AOD), columnar water vapor (CWV), single scattering albedo (SSA) and size distribution) retrieved from sunphotometer measurements during March 2012–August 2013, (b) satellite AOD and active fire products, (c) the attenuated backscatter profiles from the space-born lidar, and (d) the back-trajectories. The mean AOD440nm and extinction Angstrom exponent (EAE440−870) at KM are 0.42±0.32 and 1.25±0.35, respectively. Seasonally, high AOD440nm (0.51±0.34), low EAE440−870 (1.06±0.34) and high CWV (4.25±0.97cm) during the wet season (May – October) contrast with their counterparts 0.17±0.11, 1.40±0.31 and 1.91±0.37cm during the major dry season (November–February) and 0.53±0.29, 1.39±0.19, and 2.66±0.44cm in the late dry season (March–April). These contrasts between wet and major dry season, together with the finding that the fine mode radius increases significantly with AOD during the wet season, suggest the importance of the aerosol hygroscopic growth in regulating the seasonal variation of aerosol properties. BB and Urban/Industrial (UI) aerosols are two major aerosol types. Back trajectory analysis shows that airflows on clean days during the major dry season are often from west of KM where the AOD is low. In contrast, air masses on polluted days are from west (in late dry season) and east (in wet season) of KM where the AOD is often large. BB air mass is found mostly originated from North Burma where BB aerosols are lifted upward to 5km and then subsequently transported to southwest China via prevailing westerly winds.

Seasonal prevalence of bovine fasciolosis and its direct economic losses (del) due to liver condemnation at Makurdi abattoirs north central Nigeria

This study was conducted to report the prevalence of bovine fasciolosis and to estimate the direct economic losses (DEL) from condemnation of liver as a result of detection of lesions of fasciolosis in cattle slaughtered in Makurdi abattoirs. Retrospective data were collected from the abattoir records obtained from Ministry of Agriculture and Natural Resources (MANR) Makurdi, from 2008 to 2012. Direct economic losses were calculated based on a pilot study to determine the average price of liver per kilogram (AvP/kg) and using the formula: DEL = 𝑛w × AvP/kg, where 𝑛 is the number of livers condemned and 𝑊 is the average liver weight in kg. Between 2008 and 2012, 64,978 cattle were slaughtered at Makurdi abattoirs, out of which 9,478 cattle were infected with Fasciola species. This represents an overall prevalence of 14.56% (95%, C.I.: 12.99 – 16.85%). Annual prevalence of bovine fasciolosis was significantly (P <0.05) high in 2010 and decreased from 2011 to 2012. During the late dry season, the prevalence of bovine fasciolosis was significantly high (P <0.05). A total of 4220 liver were condemned during the study period. This amounted to 12660 kg and valued at ₦12,660,000.00 ($79251.60 USD). The highest prevalence was recorded during the late dry season. However, cattle acquire the infection during the wet season and early dry season. Pathological lesions were much obvious during the late dry season possibly when the animals were most stressed, hence we suggest that control measures should be targeted towards wet and early dry seasons. Bovine fasciolosis is prevalent in cattle slaughtered in Makurdi abattoirs and accounts for huge financial losses. Keywords: Bovine fasciolosis, Economic losses, Makurdi, Prevalence, Season

Epidemiological study on abomasal nematodes in slaughtered small ruminants raised in the guinea savannah zone of Nigeria

Gastrointestinal nematodes are one of the major causes of productivity losses in small ruminants in sub-Saharan Africa. A study was carried out to evaluate the prevalence, worm burden of abomasal nematodes and associated faecal egg counts (FEC) of small ruminants slaughtered from November, 2011 to October, 2012. Two genera of adult abomasal nematodes recovered were Haemonchus spp. and Trichostrongylus spp . Goats had the prevalence of 78.5% and 17.5% for Haemonchus spp and Trichostrongylus spp ., respectively while sheep had prevalence of 85% and 31% for Haemonchus spp. and Trichostrongylus spp. A significant difference (p<.005) was observed between host species (goats and sheep), age and sex of animal. There was a seasonal arrest of Haemonchus spp. which was greater during the late dry season than other seasons. Faecal examination revealed Strongyle egg (71% in sheep and 62% in goats) being the most prevalent followed by Strongyloides (8% in sheep and 8.2% in goats) and Trichuris (4% in sheep and 6% in goats) eggs. The mean FEC in sheep for Strongyloides, Strongyle and Trichuris were 4208±343.1, 2966±435.7 and 90±23.80, respectively. The mean FEC in goats for Strongyloides, Strongyle and Trichuris were 2630±138.8, 1301±189.9 and 138.8± 30.39, respectively. The prevalence of worm and FEC showed a definite seasonal sequence that corresponded with the regional relative humidity and rainfall pattern. This knowledge is important for the control of nematode infection in small ruminants in Nigeria. Keywords : Abomasum, Nematodes, Season, Small Ruminants, Worm burden

Chimpanzee (Pan troglodytes verus) Diet Composition and Food Availability in a Human-Modified Landscape at Lagoas de Cufada Natural Park, Guinea-Bissau

Nonhuman primate populations are facing widespread conversion of their habitat to human-modified landscapes dominated by agriculture, in which cultivated species may constitute alternative food resources, particularly during periods of wild food scarcity. We assessed intraseasonal variation in dietary composition and diversity of the western chimpanzee (Pan troglodytes verus) at Lagoas de Cufada Natural Park, Guinea-Bissau, a forest-savannah mosaic disturbed by humans, in relation to food availability. We also investigated spatial variation in dietary composition. We collected phenological data from March 2011 to February 2012 by sampling focal plant taxa and conducted macroscopic analyses of fecal samples and feeding remains during the dry season (February-May and October-December) of 2011. More fruits were available in the dry than in the wet season, and ripe fruit availability peaked in the late dry season. Chimpanzees showed a fruit-based diet composed of 31 identified plant species. Fecal samples (N = 210) were dominated by wild species (82 % volume), while cultivated species were rare (0.9 % volume; 17 % volume of unidentified species). The consump- tion of fruit species increased with ripe fruit availability, but a few wild fruit species were selected disproportionately to their overall availability. There was no association between dietary composition and distances among fecal samples, suggesting that chimpanzees have access to and largely use the same set of plant species over the

Herbivore population regulation and resource heterogeneity in a stochastic environment.

Large-mammal herbivore populations are subject to the interaction of internal density-dependent processes and external environmental stochasticity. We disentangle these processes by linking consumer population dynamics, in a highly stochastic environment, to the availability of their key forage resource via effects on body condition and subsequent fecundity and mortality rates. Body condition and demographic rate data were obtained by monitoring 500 tagged female goats in the Richtersveld National Park, South Africa, over a three-year period. Identifying the key resource and pathway to density dependence for a population allows environmental stochasticity to be partitioned into that which has strong feedbacks to population stability, and that which does not. Our data reveal a density- dependent seasonal decline in goat body condition in response to concomitant density-dependent depletion of the dry-season forage resource. The loss in body condition reduced density-dependent pregnancy rates, litter sizes, and pre-weaning survival. Survival was lowest following the most severe dry season and for juveniles. Adult survival in the late-dry season depended on body condition in the mid-dry season. Population growth was determined by the length of the dry season and the population size in the previous year. The RNP goat population is thereby dynamically coupled primarily to its dry-season forage resource. Extreme environmental variability thus does not decouple consumer resource dynamics, in contrast to the views of nonequilibrium protagonists.

Spatial distribution of temporal dynamics in anthropogenic fires in miombo savanna woodlands of Tanzania.

BackgroundAnthropogenic uses of fire play a key role in regulating fire regimes in African savannas. These fires contribute the highest proportion of the globally burned area, substantial biomass burning emissions and threaten maintenance and enhancement of carbon stocks. An understanding of fire regimes at local scales is required for the estimation and prediction of the contribution of these fires to the global carbon cycle and for fire management. We assessed the spatio-temporal distribution of fires in miombo woodlands of Tanzania, utilizing the MODIS active fire product and Landsat satellite images for the past ~40 years.ResultsOur results show that up to 50.6% of the woodland area is affected by fire each year. An early and a late dry season peak in wetter and drier miombo, respectively, characterize the annual fire season. Wetter miombo areas have higher fire activity within a shorter annual fire season and have shorter return intervals. The fire regime is characterized by small-sized fires, with a higher ratio of small than large burned areas in the frequency-size distribution (β = 2.16 ± 0.04). Large-sized fires are rare, and occur more frequently in drier than in wetter miombo. Both fire prevalence and burned extents have decreased in the past decade. At a large scale, more than half of the woodland area has less than 2 years of fire return intervals, which prevent the occurrence of large intense fires.ConclusionThe sizes of fires, season of burning and spatial extent of occurrence are generally consistent across time, at the scale of the current analysis. Where traditional use of fire is restricted, a reassessment of fire management strategies may be required, if sustainability of tree cover is a priority. In such cases, there is a need to combine traditional and contemporary fire management practices.

Seasonal sensitivity of genotypes in the humid tropics and its application to chicken breeding

Abstract. The study was aimed at elucidating the effect of seasons, namely the early wet (EW), late wet (LW), early dry (ED) and late dry (LD) seasons, on genotype sensitivity, its magnitude and application for selection and management of chickens of Bovan Nera (BN) and ISA Brown (IB) origins. Breeding and hatching records from 1999 to 2008 were collected from CHI (Ajanla) Farms and hatchery records, Ibadan, Nigeria. Cock weight (CW), hen weight (HW), hen-house egg production (HHP), egg weight (EW), fertility of egg set (FES) and pullet day-old chicks (PDC) hatched were examined. ANOVA revealed that there was significant (P &lt; 0.05) genotype × season interaction effect. This interaction was observed between genotypic values when compared between seasons within parameters. Within-season sensitivity parameters indicated that BN was more sensitive than IB in HW and FES for all seasons. In ED and LD seasons, sensitivity values were inconsistent in pattern with output levels of FES, HES and PDC hatched because of interaction between genotypes and seasons. Within the LW season, all sensitivity indices for genotypes were consistent in magnitude with productive and reproductive values. Therefore, a genotype's seasonal sensitivity indices could be utilized for direct antagonistic selection in LW season between genotypes in humid tropics.

Influence of Fire Mosaics, Habitat Characteristics and Cattle Disturbance on Mammals in Fire-Prone Savanna Landscapes of the Northern Kimberley.

Patch mosaic burning, in which fire is used to produce a mosaic of habitat patches representative of a range of fire histories (‘pyrodiversity’), has been widely advocated to promote greater biodiversity. However, the details of desired fire mosaics for prescribed burning programs are often unspecified. Threatened small to medium-sized mammals (35 g to 5.5 kg) in the fire-prone tropical savannas of Australia appear to be particularly fire-sensitive. Consequently, a clear understanding of which properties of fire mosaics are most instrumental in influencing savanna mammal populations is critical. Here we use mammal capture data, remotely sensed fire information (i.e. time since last fire, fire frequency, frequency of late dry season fires, diversity of post-fire ages in 3 km radius, and spatial extent of recently burnt, intermediate and long unburnt habitat) and structural habitat attributes (including an index of cattle disturbance) to examine which characteristics of fire mosaics most influence mammals in the north-west Kimberley. We used general linear models to examine the relationship between fire mosaic and habitat attributes on total mammal abundance and richness, and the abundance of the most commonly detected species. Strong negative associations of mammal abundance and richness with frequency of late dry season fires, the spatial extent of recently burnt habitat (post-fire age <1 year within 3 km radius) and level of cattle disturbance were observed. Shrub cover was positively related to both mammal abundance and richness, and availability of rock crevices, ground vegetation cover and spatial extent of ≥4 years unburnt habitat were all positively associated with at least some of the mammal species modelled. We found little support for diversity of post-fire age classes in the models. Our results indicate that both a high frequency of intense late dry season fires and extensive, recently burnt vegetation are likely to be detrimental to mammals in the north Kimberley. A managed fire mosaic that reduces large scale and intense fires, including the retention of ≥4 years unburnt patches, will clearly benefit savanna mammals. We also highlighted the importance of fire mosaics that retain sufficient shelter for mammals. Along with fire, it is clear that grazing by introduced herbivores also needs to be reduced so that habitat quality is maintained.