44 research outputs found

    Going through the motions : the impacts of frequent fires and grazing pressure on reproduction of Montane grassland birds

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    Bibliography: leaves 138-147.Land management practices have been implicated as a cause for the decline of many grassland-nesting birds across the globe. While this effect has motivated extensive research and conservation in the developed northern hemisphere, it remains poorly addressed in southern hemisphere. Between 1998 and 2001 I examined the effect of fire frequency and grazing intensity on the density, breeding biology and nesting success of several grassland bird species that breed in the high altitude grasslands of Wakkerstroom, South Africa. I established study plots in heavily grazed and annually burned, lightly grazed and annually burned, and lightly grazed and biennially burned plots. These represent the most frequently used grassland management regimes in this region. Independent analysis of all study species showed that daily nesting success was higher under light than heavy grazing. Similarly, nesting success was higher under biennial burning when compared to annual burning. Nest predation was the major cause of nest failure during all three years for all species. The likelihood of nest predation clearly depended upon foliage in the immediate vicinity of the nest and vegetation within 10 m radius of the nest (the nest patch). In general, variables important in discriminating between successful and depredated nests across all species were directly related to vegetation cover, density and horizontal heterogeneity. I also examined micro-habitat choices, the form of natural selection and the adaptiveness of preferences in four coexisting grassland bird species (Yellow-breasted Pipit Hemimacronyx chloris, Grassveld Pipit Anthus cinamomerous, Orange-throated Longclaw Macrony capensis, and Ayre's Cisticola Cisticola ayressii). Breeding birds selected nest patches non-randomly and this differed between species. Comparison of vegetation features at successful and unsuccessful nests supported the idea that nesting success is a strong selective force on habitat choice. Nest success was higher in preferred than non-preferred habitat for all the four species, suggesting that preferences were adaptive. Estimation of fitness functions relating fitness of individuals to critical habitat features suggests that natural selection might favour preferences for specific habitat features. Although food abundance and thus amount of food available to populations of breeding birds significantly differed between management regimes, the study yielded no evidence for an effect of management-mediated food abundance on feeding rate, nestling provisioning rates, nestling growth rates, body condition, nest attentiveness and brooding effort. My results suggest that the food availability alone may not be the most important factor influencing the production of offspring. Instead, nest predation appeared to be of major importance in this system. Theoretically, nest predation increases with activity at nests, and predation rates should peak during the nestling stage when birds are feeding young. I tested this hypothesis using three ecologically similar grassland bird species (Yellow-breasted Pipit, Orange-throated Longclaw, and Grassveld Pipit). Parental activity was indeed greater during the nestling than incubation stage. Nest predation, however, did not increase with parental activity between these stages in all three study species. I conducted an experiment that controlled for parental activity (by reusing natural nests of the study species with artificial clutches) in order to test for nest-site effects. Nests that had a high risk of predation when used by active parents had a correspondingly high risk of predation when the same nests were re-used with artificial clutches (i.e. when controlling for parental activity). This result supports the notion that variation in nest-site quality often affects nest predation risk, and such effects could mask parental activity effects on nest predation. Once-nest site effects were accounted for, nest predation showed a positive increase with parental activity during the nestling stage within and across species. Collectively, the chapters of this thesis help to diagnose the causes and underlying mechanisms of grassland bird population decreases, and help to identify the most effective conservation actions. In short, conservation effort for grassland species should be directed at ensuring that their preferred critical nesting habitat is managed appropriately. I propose that current intensive grazing pressure and periodic burning should be relaxed by reducing stocking rates and burning less frequently to benefit grassland bird species. Ideally, grasslands should be burned biennially and grazed moderately

    Effects of human activities on birds and their habitats as reported by forest user groups in and around North Nandi Forest, Kenya

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    Species-rich tropical forests are becoming increasingly fragmented, degraded and are declining due to human activities, threatening the survival of avian species that depend on them. We assessed the detrimental effects of human activities on birds and their habitats in and around North Nandi Forest. A semi-structured questionnaire survey was used to collect data on human activities affecting birds and their habitats among forest users and forest protectors in North Nandi Forest. Habitat destruction (70%) was the main detrimental human activity on avifaunal habitats, while hunting of birds for subsistence use (10%) only affected certain bird species. The age group between 20 and 40 years used the forest most frequently and most activities were undertaken in indigenous forest habitat. Significantly, men undertook timber extraction and livestock grazing, while women undertook collection of firewood and medicinal herbs. Illegal forest exploitation should be curbed in order to ensure future survival of avifaunal diversity in North Nandi Forest

    Immune function differs among tropical environments but is not downregulated during reproduction in three year-round breeding equatorial lark populations

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    Seasonal variation in immune function can be attributed to life history trade-offs, and to variation in environmental conditions. However, because phenological stages and environmental conditions co-vary in temperate and arctic zones, their separate contributions have not been determined. We compared immune function and body mass of incubating (female only), chick-feeding (female and male), and non-breeding (female and male) red-capped larks Calandrella cinerea breeding year-round in three tropical equatorial (Kenya) environments with distinct climates. We measured four immune indices: haptoglobin, nitric oxide, agglutination, and lysis. To confirm that variation in immune function between breeding (i.e., incubating or chick-feeding) and non-breeding was not confounded by environmental conditions, we tested if rainfall, average minimum temperature (Tmin), and average maximum temperature (Tmax) differed during sampling times among the three breeding statuses per location. Tmin and Tmax differed between chick-feeding and non-breeding, suggesting that birds utilized environmental conditions differently in different locations for reproduction. Immune indices did not differ between incubating, chick-feeding and non-breeding birds in all three locations. There were two exceptions: nitric oxide was higher during incubation in cool and wet South Kinangop, and it was higher during chick-feeding in the cool and dry North Kinangop compared to non-breeding birds in these locations. For nitric oxide, agglutination, and lysis, we found among-location differences within breeding stage. In equatorial tropical birds, variation in immune function seems to be better explained by among-location climate-induced environmental conditions than by breeding status. Our findings raise questions about how within-location environmental variation relates to and affects immune function

    Home-ranges of tropical Red-capped Larks are influenced by breeding rather than vegetation, rainfall or invertebrate availability

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    Home-range studies have received considerable attention from ecologists but are greatly skewed towards the north temperate areas. Tropical areas offer an ideal setting to tease apart hypotheses about weather, food availability and social interactions as important factors influencing home-range. In this study, we investigated home-range and movement patterns of the tropical Red-capped Lark Callandrella cineria, a year-round breeding bird with a dynamic social structure. We tracked 56 individuals using radiotransmitters and colour-ring readings over a 23-month period. Our objective was to understand year-round variation in home-range size in the context of the highly aseasonal and unpredictable variation in weather and resources typical of many equatorial habitats, in addition to the birds? changing social structure and year-round breeding. The mean composite monthly home-range of Red-capped Larks was 58.0 ha, and the mean individual home-range size was 19.9 ha, but this varied considerably between individuals. The total number of nests found per month (breeding intensity) best predicted home-range size of non-breeding birds, and of breeding and non-breeding birds combined. We show for the first time that breeding intensity decreases the home-range size of non-breeding individuals. Our study also underlines the relevance of conducting more studies in aseasonal tropical areas in order to disentangle effects of weather, food availability and breeding that vary in parallel, peaking simultaneously in most seasonal areas

    Fluctuating asymmetry and environmental stress : understanding the role of trait history

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    While fluctuating asymmetry (FA; small, random deviations from perfect symmetry in bilaterally symmetrical traits) is widely regarded as a proxy for environmental and genetic stress effects, empirical associations between FA and stress are often weak or heterogeneous among traits. A conceptually important source of heterogeneity in relationships with FA is variation in the selection history of the trait(s) under study, i.e. traits that experienced a (recent) history of directional change are predicted to be developmentally less stable, potentially through the loss of canalizing modifiers. Here we applied X-ray photography on museum specimens and live captures to test to what extent the magnitude of FA and FA-stress relationships covary with directional shifts in traits related to the flight apparatus of four East-African rainforest birds that underwent recent shifts in habitat quality and landscape connectivity. Both the magnitude and direction of phenotypic change varied among species, with some traits increasing in size while others decreased or maintained their original size. In three of the four species, traits that underwent larger directional changes were less strongly buffered against random perturbations during their development, and traits that increased in size over time developed more asymmetrically than those that decreased. As we believe that spurious relationships due to biased comparisons of historic (museum specimens) and current (field captures) samples can be ruled out, these results support the largely untested hypothesis that directional shifts may increase the sensitivity of developing traits to random perturbations of environmental or genetic origin

    Geographical and temporal variation in environmental conditions affects nestling growth but not immune function in a year-round breeding equatorial lark

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    Background: Variation in growth and immune function within and among populations is often associated with specific environmental conditions. We compared growth and immune function in nestlings of year-round breeding equatorial Red-capped Lark Calandrella cinerea from South Kinangop, North Kinangop and Kedong (Kenya), three locations that are geographically close but climatically distinct. In addition, we studied growth and immune function of lark nestlings as a function of year-round variation in breeding intensity and rain within one location. We monitored mass, wing, and tarsus at hatching (day 1) and at 4, 7, and 10 days post-hatch, and we quantified four indices of immune function (haptoglobin, agglutination, lysis and nitric oxide) using blood samples collected on day 10. Results: Nestling body mass and size at hatching, which presumably reflect the resources that females allocated to their eggs, were lowest in the most arid location, Kedong. Contrary to our predictions, nestlings in Kedong grew faster than nestlings in the two other cooler and wetter locations of South and North Kinangop. During periods of peak reproduction within Kedong, nestlings were heavier at hatching, but they did not grow faster over the first 10 days post-hatch. In contrast, rainfall, which did not relate to timing of breeding, had no effect on hatching mass, but more rain did coincide with faster growth post-hatch. Finally, we found no significant differences in nestling immune function, neither among locations nor with the year-round variation within Kedong. Conclusion: Based on these results, we hypothesize that female body condition determines nestling mass and size at hatching, but other independent environmental conditions subsequently shape nestling growth. Overall, our results suggest that environmental conditions related to food availability for nestlings are relatively unimportant to the timing of breeding in equatorial regions, while these same conditions do have consequences for nestling size and growth.</p

    The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

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    Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015

    Syringophiloidus picidus Skoracki, Klimovičová, Muchai & Hromada, 2014, sp. nov.

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    Syringophiloidus picidus sp. nov. (Figs. 4 and 5) Description. FEMALE, holotype. Total body length 605 (595–685 in 13 paratypes). Gnathosoma. Infracapitulum punctate. Each medial branch of peritremes with 6–7 chambers, each lateral branch with 9–10 chambers. Stylophore punctate, 165 (155–170) long, basal part of its dorsum with striae ornament. Idiosoma. Propodonotal shield punctate near bases of setae ve and si. Length ratio of setae vi: ve: si 1: 1.2–1.3: 1.7–2.3. Bases of setae c 1 and se situated at same transverse level. All propodonotal and hysteronotal setae are discernibly serrated, other idiosomal setae smooth. Hysteronotal shield fused to pygidial shield, punctate in posterior part, bases of setae d 2 and d 1 situated on this shield. All hysteronotal setae subequal in length. Genital plate present, bases of setae ag 2 and ag 3 situated on margin of this plate. Length ratio ag 1: ag 3 1: 1.6. Pseudanal setae subequal in length, genital setae g 1 slightly (1.2 times) longer than g 2. All coxal fields punctate. Legs. Fan-like setae p ’and p” of legs III and IV with 5 tines. Setae tc”III–IV about twice as long as tc ’ III–IV. Lengths of setae: vi 35 (25–35), ve 45 (30–45), si 60 (60–80), c 1 210 (215), c 2 (155–180), se (185–195), d 1 150 (130–145), d 2 150 (145–160), e 2 145 (115–155), f 1 15 (10–20), f 2 175 (150–180), h 1 25 (25–40), h 2 (315–395), ps 1 15 (10–15), ps 2 15 (15), g 1 30 (25–40), g 2 25 (25–40), ag 1 115 (110–160), ag 2 (115–155), ag 3 180 (145–205), tc ’ III–IV 25 (25–30), tc” III–IV 55 (55). MALE (4 paratypes). Total body length 395–415. Gnathosoma. Infracapitulum sparsely punctate. Each medial branch of peritremes with 6–7 chambers, each lateral branch with 9–10 chambers. Stylophore apunctate, 135–145 long. Idiosoma. Propodonotal shield with concave anterior margin, apunctate, bearing bases of setae vi, ve, si and c 1, setae se located near this shield. Length ratio of setae vi: ve: si 1: 1.2: 1.2–1.4. Hysteronotal shield absent. Setae d 2 2–3 times longer than d 1 and e 2. Setae f 2 and h 2 situated on oval pygidial shield. Setae h 2 2–3 times longer than f 2. Coxal fields I–IV apunctate. Legs. Fan-like setae p ’ and p” of legs III–IV with 4 tines. Lengths of setae: vi 20– 30, ve 25–35, si 30–35, c 1 105–130, c 2 95–105, se 115–145, d 1 20, d 2 45–65, e 2 15 –20, f 2 20–25, h 2 45–60, ag 1 55–65, tc ’ III–IV 15–20, tc” III–IV 30. Type material. Female holotype, 13 female and 4 male paratypes from quill of secondary feather of Dendropicos fuscescens (Vieillot) (Piciformes: Picidae); KENYA, Mutanda, 17 September 1945, coll. unknown. Type deposition. All type material is deposited in the AMU (Reg. No. AMU-SYR. 445), except 2 female paratypes in the ZISP (Reg. No. ZISP-AVB-011- 2908 -066), and 1 female paratype in the NMK (NMK-03MH). Additional material. From type host species; UGANDA, Bombo, 14 August 1923, coll. unknown: 2 females, deposited in the AMU (Reg. No. AMU-SYR. 445 B); UGANDA, Masindi, Bunyoro district, 4 December 1959, coll. unknown: 8 females, deposited in the AMU (Reg. No. AMU-SYR. 445 C); TANZANIA, Songea, 24 June 1964, coll. unknown: 7 females, deposited in the AMU (Reg. No. AMU-SYR. 445 D). Differential diagnosis. This new species is morphologically similar to Syringophiloidus carolae Skoracki, Flannery et Spicer, 2009 described from Cardinalis cardinalis (Linnaeus) (Passeriformes: Cardinalidae) (Skoracki et al. 2009). In females of both species, the infracapitulum is punctate; each lateral branch of the peritremes has 9– 10 chambers; the propodonotal shield is punctate; the hysteronotal shield is fused to the pygidial shield. These species are distinguished as follow: in females of Syringophiloidus picidus, each medial branch of the peritremes has 6–7 chambers; the length ratio of setae vi: ve: si is 1: 1.2–1.3: 1.7–2.3, and all of propodonotal and hysteronotal setae are discernibly serrated. In females of Syringophiloidus carolae, each medial branch of the peritremes has 3 chambers; the length ratio of setae vi: ve: si is 1: 3–3.4: 5–6.5, and all propodonotal and hysteronotal setae are lightly serrated. Etymology. The specific name refers to the family name of the host.Published as part of Skoracki, Maciej, Klimovičová, Miroslava, Muchai, Muchane & Hromada, Martin, 2014, New taxa of the family Syringophilidae (Acari: Prostigmata) from African barbets and woodpeckers (Piciformes: Lybiidae, Picidae), pp. 178-188 in Zootaxa 3768 (2) on pages 184-187, DOI: 10.11646/zootaxa.3768.2.5, http://zenodo.org/record/22719

    Effect of logging on the Abbott's Starling (Pholia femoralis) population in Kikuyu escarpment forest, Kenya

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    Human encroachment continues to degrade highland forests. Abbott's Starling (Pholia femoralis) is a little-known Eastern African endemic frugivore restricted to highland forest canopy at altitudes of 1 800–2 600m. It occurs patchily within its restricted range of about 5 100km2, its global population of 1 250–5 000 pairs is declining and it is listed in the IUCN Red Data List as Globally Vulnerable. In Kenya, it inhabits Mt Kenya forests, the Kikuyu escarpment forest, and occasionally the Taita and Chyulu Hills, while in Tanzania it lives in forests of Mounts Kilimanjaro, Meru and North Pare. We studied the bird's distribution in two primary and two disturbed blocks of the Kikuyu escarpment forest from August to September 2003. Twelve transects, averaging 1.8km each, were established to determine the logging patterns and to count P. femoralis at 130 points, using recorded calls. A total of 16 birds were sighted in the main Kereita block in three out of five transects, perching at a mean height of 30m. Possibly due to rainy weather, no sightings were made in Kieni block. The bird appeared to be sensitive to human disturbance, preferring secluded forest sections of tall indigenous trees with discontinuous canopy. This suggests that this species will only survive at this locality if logging and other forms of forest use do not exceed current levels. Ostrich 2007, 78(2): 299–30
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