West Nile Virus and California Breeding Bird Declines

Since it was first detected in 1999, West Nile virus (WNV) quickly spread, becoming the dominant vector-borne disease in North America. Sometimes fatal to humans, WNV is even more widespread among birds, with hundreds of species known to be susceptible to WNV infection in North America alone. However, despite considerable mortality and local declines observed in American crows (Corvus brachyrhynchos), there has been little evidence of a large regional association between WNV susceptibility and population declines of any species. Here we demonstrate a correlation between susceptibility to WNV measured by large-scale testing of dead birds and two indices of overall population change among bird species following the spread of WNV throughout California. This result was due primarily to declines in four species of Corvidae, including all species in this family except common ravens (Corvus corax). Our results support the hypothesis that susceptibility to WNV may have negative population consequences to most corvids on regional levels. They also provide confirmation that dead animal surveillance programs can provide important data indicating populations most likely to suffer detrimental impacts due to WNV.     

Occurrence of the Brown-necked Raven,Corvus ruficollis,at Cizre in Eastern Turkey

An adult male of Maynard's Longnose Sand Snake (Lytorhynchus maynardi) was collected on 24 July 2009 from the east of Sistan and Baluchistan Province in south-eastern Iran. The new locality is the westernmost record of this species in western Asia, and the first record for 42 years from Iran. Information on the geographic distribution of the genus Lytorhynchus Peters, 1863 in Iran, comparative morphology and some ecological data are presented here.     

Dynamics and Phylogenetic Implications of MtDNA Control Region Sequences in New World Jays (Aves: Corvidae)

To study the evolution of mtDNA and the intergeneric relationships of New World Jays (Aves: Corvidae), we sequenced the entire mitochondrial DNA control region (CR) from 21 species representing all genera of New World jays, an Old World jay, crows, and a magpie. Using maximum likelihood methods, we found that both the transition/transversion ratio (κ) and among site rate variation (α) were higher in flanking domains I and II than in the conserved central domain and that the frequency of indels was highest in domain II. Estimates of κ and α were much more influenced by the density of taxon sampling than by alternative optimal tree topologies. We implemented a successive approximation method incorporating these parameters into phylogenetic analysis. In addition we compared our study in detail to a previous study using cytochrome b and morphology to examine the effect of taxon sampling, evolutionary rates of genes, and combined data on tree resolution. We found that the particular weighting scheme used had no effect on tree topology and little effect on tree robustness. Taxon sampling had a significant effect on tree robustness but little effect on the topology of the best tree. The CR data set differed nonsignificantly from the tree derived from the cytochrome b/morphological data set primarily in the placement of the genus Gymnorhinus, which is near the base of the CR tree. However, contrary to conventional taxonomy, the CR data set suggested that blue and black jays (Cyanocorax sensu lato) might be paraphyletic and that the brown jay Psilorhinus (=Cyanocorax) morio is the sister group to magpie jays (Calocitta), a phylogenetic hypothesis that is likely as parsimonious with regard to nonmolecular characters as monophyly of Cyanocorax. The CR tree also suggests that the common ancestor of NWJs was likely a cooperative breeder. Consistent with recent systematic theory, our data suggest that DNA sequences with high substitution rates such as the CR may nonetheless be useful in reconstructing relatively deep phylogenetic nodes in avian groups. Received: 10 November 1999 / Accepted: 16 March 2000     

Is primate tool use special? Chimpanzee and New Caledonian crow compared

The chimpanzee (Pan troglodytes) is well-known in both nature and captivity as an impressive maker and user of tools, but recently the New Caledonian crow (Corvus moneduloides) has been championed as being equivalent or superior to the ape in elementary technology. I systematically compare the two taxa, going beyond simple presence/absence scoring of tool-using and -making types, on four more precise aspects of material culture: (i) types of associative technology (tools used in combination); (ii) modes of tool making; (iii) modes of tool use; and (iv) functions of tool use. I emphasize tool use in nature, when performance is habitual or customary, rather than in anecdotal or idiosyncratic. On all four measures, the ape shows more variety than does the corvid, especially in modes and functions that go beyond extractive foraging. However, more sustained field research is required on the crows before this contrast is conclusive.     

Varied diet and opportunistic foraging in the Ethiopian Bush-crow Zavattariornis stresemanni,an Endangered generalist

The Ethiopian Bush-crow Zavattariornis stresemanni is an endangered, co-operatively breeding southern Ethiopian endemic with a remarkably restricted range (c. 6 000 km²). The species’ range was recently found to be almost perfectly predicted by an envelope of cooler, drier and more seasonal climate than surrounding areas, but the proximate determinants of this range restriction remain unclear. We assessed whether specialisation in diet or foraging may restrict the range of the species by conducting foraging watches to determine prey composition, augmented by observations of opportunistic foraging techniques, and by comparing our results to previously published information on diet. Prey composition comprised a range of arthropods, such as insect larvae (62.7%), beetles (Coleoptera) (15.6%), and grasshoppers and crickets (Orthoptera) (11.8%). Prey was primarily obtained by pecks above ground (74.2%) but also frequently dug up (23.8%). Prey capture was most successful during pecks and we also found chicks were preferentially fed larger prey items over smaller ones by adults. We documented opportunistic behaviours such as nest-raiding and ox-pecking. Diet and foraging are varied and unspecialised, and therefore do not appear to explain the restricted range of the Ethiopian Bush-crow.     

Corvid interference with Canid Pest Ejectors in the southern rangelands of Western Australia

Canid Pest Ejectors (CPE) are a method of population management that has recently been approved for the control of wild dogs and foxes in Australia. A pilot trial of CPEs (n = 10) targeting wild dogs was conducted in the southern rangelands of Western Australia in the winter of 2017. CPEs were deployed for 81 days, which included periods of significant rainfall. CPEs were not serviced during deployment, which is a likely situation for remote areas where access may be limited. During deployment, all ejector units corroded and plastic capsules containing 1080 degraded (but did not leak). For CPEs to remain effective in the field, they require regular inspections and servicing, particularly in wet conditions. Interference by nontarget corvid species was observed. Six CPEs were interfered with by corvids, with the lures removed from three, partially removed from another two and one disassembled. Our data suggest that corvid interference with ejectors may have a significant impact on the efficiency and safety of their use. Further investigation into the usefulness of Canid Pest Ejectors as method of canid control is required for rangeland use.     

Relative differentiation of skeletal elements in European corvids

Summary The study compares mensural differences between various species of European corvids in all major skeletal elements. It appears that the greatest differences are found in the bill and mandible, which may reflect adaptations to various foods and feeding methods. Substantiation of this supposition, however, calls for further studies.

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Relative Differenzierung der Skelettelemente bei europäischen Corviden

Zusammenfassung Ein morphometrischer Vergleich europäischer Corviden-Arten nach allen wichtigen Skelettmerkmalen zeigt, dass die größten Unterschiede zwischen den Arten im Ober- und Unterschnabelbau bestehen. Dies wird als Anpassungen an verschiedene Nahrung und Ernährungsmethoden erklärt. Diese Vermutung erfordert jedoch noch weitere Untersuchungen.

     

An analysis of population genetic differentiation and genotype–phenotype association across the hybrid zone of carrion and hooded crows using microsatellites and MC1R

The all black carrion crow ( Corvus corone corone ) and the grey and black hooded crow ( Corvus   corone cornix ) meet in a narrow hybrid zone across Europe. To evaluate the degree of genetic differentiation over the hybrid zone, we genotyped crows from the centre and edges of the zone, and from allopatric populations in northern (Scotland–Denmark–Sweden) and southern Europe (western–central northern Italy), at 18 microsatellites and at a plumage candidate gene, the MC1R gene. Allopatric and edge populations were significantly differentiated on microsatellites, and populations were isolated by distance over the hybrid zone in Italy. Single-locus analyses showed that one locus, CmeH9, differentiated populations on different sides of the zone at the same time as showing only weak separation of populations on the same side of the zone. Within the hybrid zone there was no differentiation of phenotypes at CmeH9 or at the set of microsatellites, no excess of heterozygotes among hybrids and low levels of linkage disequilibrium between markers. We did not detect any association between phenotypes and nucleotide variation at MC1R , and the two most common haplotypes occurred in very similar frequencies in carrion and hooded crows. That we found a similar degree of genetic differentiation between allopatric and edge populations irrespectively of their location in relation to the hybrid zone, no differentiation between phenotypes within the hybrid zone, and neither heterozygote excess nor consistent linkage disequilibrium in the hybrid zone, is striking considering that carrion and hooded crows are phenotypically distinct and sometimes recognised as separate species.