Interspecific and intraspecific differences in habitat use and their conservation implications for Palaearctic harriers on Sahelian wintering grounds

The floodplains of the West‐African Sahel region have experienced extensive habitat transformation during the past four decades, coinciding with an impoverishment of raptor populations. We investigated foraging patterns of Palaearctic migratory Eurasian Marsh Harriers Circus aeruginosus, Pallid Harriers C. macrourus and Montagu’s Harriers C. pygargus on a floodplain system in northern Cameroon to assess species, sex‐ and age‐related habitat preferences. Sex and age have rarely been incorporated into general studies of raptor habitat associations, despite clear evidence of intrasexual and age‐related differences in foraging strategies and diet composition, potentially carrying strong conservation implications. We found evidence of sexual differences in foraging preference related to land use, particularly in the most sexually dimorphic Pallid Harrier, and evidence that juveniles used different habitats to adults. This constitutes the first quantitative documentation of such differentiation by Palaearctic raptors on African wintering grounds, indicating that general patterns of habitat use in wintering raptors may obscure sex‐ and age‐specific preferences. Contrary to expectations, we found limited evidence for interspecific foraging segregation. Food partitioning by prey mass was related to harrier body mass and facilitated by a diverse availability of prey on human‐transformed floodplains. Anticipated further large‐scale conversion of floodplain habitat into predominantly desiccated grasslands raises concerns about the survival of wintering harriers.     

Mortality of developing floodplain forests subjected to a drying climate and water extraction

River regulation and water extraction have altered the hydrology of rivers resulting in substantial changes to forest structure and the dieback of floodplain forests globally. Forest mortality, due to water extraction, is likely to be exacerbated by climate change-induced droughts. In 1965, a plantation trial was established within a natural floodplain forest to examine the effect of planting density on timber production. We used data from this trial to investigate the effect of initial stand density on the structure and dynamics of Eucalyptus camaldulensis (Dehnh.) forests. Highest density stands (8000 trees ha⁻¹) were dominated by many slender trees, mostly<10 cm in diameter, whereas the lowest density stands produced size distributions with a wider range of stem diameters and higher mean and maximum stem diameter. After 1996, the study area experienced a sharp decline in water availability due to a substantial lowering of the water table, reduced flooding frequency, a pronounced rainfall deficit and increased maximum temperatures. The drought coincided with a dramatic increase in mortality in the high-density stands, yet remained little changed in low-density treatments. Our results highlight the importance of initial stand density as a key determinant of the development of forest structure. Early thinning of high-density stands is one component of a broader management approach to mitigate impacts of human-induced drought and water extraction on developing floodplain forests.     

Excretion of multiple urinary biomarkers for radical induced damage in rats treated with three different nephrotoxic compounds

In the present study the urinary excretion of seven aldehydes, acetone and coproporphyrin III as non-invasive in vivo biomarkers of free radical damage was measured in rats after treatment with three nephrotoxic compounds: cisplatin, mercuric chloride (HgCl2) and N -acetyl- S -(1,1,2,2-tetrafluoroethyl)-L-cysteine (TFE-Nac). A clear difference between the different nephrotoxic compounds was found in the time interval between dosage and maximal toxicity, as measured by clinical chemical parameters in urine. In rats treated with TFE-Nac and HgCl2 this was fast: 12 h and 24 h after treatment, respectively. In the rats treated with cisplatin, however, nephrotoxicity occurred later: 96 h-108 h after treatment. Urinary creatinine excretion was decreased in all treatments. Therefore, the excretion of the proposed biomarkers was expressed as amount excreted per 12 h urine fraction as well as amount excreted per mol creatinine in each 12 h urine fraction. Urinary excretion of coproporphyrin III was decreased in almost all 12 h urine fractions with all treatments, however, when expressed per mol creatinine, increases were found in urine of rats treated with cisplatin and HgCl2. In cisplatin-treated rats an increase was found in the excretion of formaldehyde per 12 h, but acetaldehyde, propanal and MDA levels were decreased. Expressed per mol creatinine, MDA levels were decreased, but other aldehydes were increased. In HgCl2-treated rats urinary aldehyde excretion expressed per mol creatinine was increased. In TFE-Nac treated animals the urinary levels of acetaldehyde per 12 h were increased and per mol creatinine the levels of some aldehydes were only slightly increased. With none of the treatments did the increase in the biomarkers expressed per mol creatinine exceed the decrease in creatinine excretion. Similar time intervals were found between dosage and maximal excretion of biomarkers as for the time intervals between dosage and maximal toxicity. With all treatments significant increases in the excretion of acetone were found both per 12 h and per mol creatinine, probably related to the increased glucose excretion. It was concluded that no convincing evidence for free radical damage was found in the present study with the employed biomarkers.     

Phylogeny and classification of the Culicidae (Diptera)

The generic relationships and higher classification of the family Culicidae are examined on the basis of a phylogenetic analysis. New and traditional morphological characters studied and compared throughout the Culicidae resulted in the acquisition of character data relative to the majority of species within each genus. Polymorphisms and morphological observations are discussed and additional information and illustrations are provided for the majority of characters and their character states. The analysis of seventy-three adult, pupal and fourth-instar larval characters coded for the thirty-eight currently recognized genera of mosquitoes resulted in relationships and groupings which differ significantly from traditional hypotheses. The analysis supports the monophyly of the subfamily Anophelinae and the tribes Culicini and Sabethini. The Anophelinae form the most basal clade of the family. The results indicate that Aedini is a paraphyletic assemblage with respect to the Mansoniini, each of which is monophyletic in itself. The Aedini + Mansoniini form a sister group to the Culicini + Sabethini, with the Aedini and the Culicini placed in ancestral relationships to the Mansoniini and the Sabethini, respectively. Based on the topography of generic relationships among more 'generalized' mosquitoes, the boundaries and relationships of the tribes Aedeomyiini, Uranotaeniini, Ficalbiini, Hodgesiini, Orthopodomyiini and Culisetini appear to be problematic. Relationships between genera of the tribe Aedini are generally poorly resolved due to a significant amount of polymorphism, especially within the genus Aedes as currently defined. There is no support for separate subfamily recognition for the genus Toxorhynchites , which is downgraded to tribal status as a result of the analysis. The results are discussed in relation to previous hypotheses based on subjective inference and cladistic analyses.     

Morphactin transport and metabolism in tree bark tissues: comparative studies in vitro

Bark banding of morphaction is an effective means of controling stem elongation in Pinus radiata D. Don (Monterey pine) but not Juglans regia L. (English walnut). Diffusion coefficients of ¹⁴C-labeled morphactin across excised disks of tree bark, measured in specially designed diffusion chambers, were 11 to 85 fold greater in pine than walnut. In seedlings of comparable age, the suberin layer of walnut bark is much thicker than that of pine; if the layer is removed, diffusion of ¹⁴C-morphactin is enhanced 39-fold in pine and 285-fold in walnut. Morphactin applied to the bark as an ester is rapidly hydrolyzed to its carboxylic acid derivative in both pine and walnut. This conversion occurs rapidly in the bark of both species and does not appear to limit the rate of morphactin movement across the bark. These results suggest that diffusion across the suberin layer and not metabolism limits morphactin transport across the bark.     

Evolution of Pineal Control of Endocrine Function in Lower Vertebrates

Pineal bodies, and other associated parietal structures, areremarkably varied among vertebrates These organs apparentlyassumed, in the primitive vertebrates, a principal role in integrationof photic information. The pineal photoreceptor cell seems tohave evolved into the secretory pinealocyte that is found inmost of the higher vertebrates. Along with the evolution ofthe photoreceptor element into the pinealocyte, there is a concomitantshift in the neural connection of the pineal organ. The pinealo-fugal,sensory innervation gives way to an autonomic, pinealo-petalmotor innervation. Thus, direct photosensitivity was supercededby indirect, optically-mediated control of the now secretorypineal gland. Even though pineal organs display such unusual plasticity anddiversity across groups, responsivenses to light remains a constantfeature. Photoperiod may modify the diurnallyrhythmic patternsof melatonin secretion across seasons and invoke appropriate"programs" which permit an animal to anticipate seasonal changes.Thus, melatonin may be a key molecule, attuned to photoperiodicity,which has been selected through evolution to effect adaptationto annual events.     

DDT inhibits Na<Superscript>+</Superscript>, K<Superscript>+</Superscript>, Mg<Superscript>2+</Superscript>-ATPase in the Intestinal Mucosae and Gills of Marine Teleosts

SODIUM-potassium-activated, magnesium-dependent, adenosine triphosphatase (Na⁺, K⁺, Mg²⁺-ATPase) is widely accepted as an essential factor in sodium transport¹ and observations on fish substantiate this view. There are concurrent increases, for example, of both Na⁺, K⁺, Mg²⁺-ATPase activity and osmoregulatory sodium transport², in the intestinal mucosae^3,4 and the gills^3,5 of euryhaline teleosts during adaptation to seawater. Furthermore, the gills of stenohaline seawater teleosts, which actively secrete sodium, exhibit higher Na⁺, K⁺, Mg²⁺-ATPase activity than the gills of stenohaline freshwater teleosts, which do not actively secrete sodium^3,5. Na⁺, K⁺, Mg²⁺-ATPase therefore seems to be important in maintaining tissue osmolarity well below that of seawater. It is disquieting to report therefore that Na⁺, K⁺, Mg²⁺-ATPase activity in the intestinal mucosae and gills of marine teleosts is inhibited by the organochlorine insecticide DDT. This observation may help to clarify the unexplained sensitivity of teleosts to DDT⁶.     

Consequences of habitat loss and change to populations of wintering migratory birds: predicting the local and global effects from studies of individuals

Population models show that the response of migratory bird populations to a reduction in the area, or change in the quality, of their winter feeding areas depends critically on the shape (linear or non-linear) and strength (slope) of the relationship describing how the proportion dying from starvation changes with population density. Yet the parameters that define such density-dependent functions are extremely difficult to estimate from direct measurements of mortality at different population sizes. Even if they could be estimated, there would be uncertainty as to whether or not the relationship would remain the same, and thus provide reliable predictions, in the new circumstances for which forecasts are required. This paper summarizes studies of the Oystercatcher Haematopus ostralegus which aim to derive the shape and strength of the winter density-dependent mortality and emigration function for one estuary, under existing and new circumstances, from the responses of individual birds to each other and to their spatially and seasonally varying food supply. Based on these studies, an individuals-based, physiologically structured game theoretic distribution model has been built which predicts the carrying capacity and numbers of birds dying at different population sizes. The model also can be applied to Oyster-catchers occupying several estuaries distributed throughout their wintering range and can thus be extended to the entire biogeographical or global population. In addition, it can be used to identify some easily measured behavioural and ecological parameters that identify those species, from a wide range of taxa, that are most likely to be affected by habitat loss and change.     

Development Anthropology: Encounters in the Real World

Development Anthropology: Encounters in the Real World. Riall Nolan. Cambridge: Westview Press, 2002. 345 pp.