Delineating the fishes of the Clinus superciliosus species complex in southern African waters (Blennioidei: Clinidae: Clinini), with the validation of Clinus arborescens Gilchrist & Thompson, 1908 and Clinus ornatus Gilchrist & Thompson, 1908, and with descriptions of two new species

The Clinus superciliosus complex comprises six closely related species. Three of the species were originally recognized by Gilchrist and Thompson as two distinct species, Clinus superciliosus (Linnaeus, 1758) and Clinus ornatus Gilchrist & Thompson, 1908, and a variety, Clinus superciliosus var. arborescens Gilchrist & Thompson, 1908. A number of other authors described various similar species, which subsequently were all synonymized with Clinus superciliosus. A further species, Clinus spatulatus Bennett, 1983, an obligate estuarine dweller, is known only from the Bot, Kleinmond, and Klein river estuaries in the Western Cape, South Africa. Two further species, Clinus musaicus sp. nov. (discovered while searching for C. ornatus specimens) and Clinus exasperatus sp. nov. , are herein described: the first is currently known from False Bay and the west coast of the Cape Peninsula, whereas the second species is known from only two specimens just east of False Bay. Clinus ornatus and Clinus arborescens Gilchrist & Thompson, 1908 are recognized as a valid species, and can be distinguished from C. superciliosus and C. spatulatus on the basis of meristic values, form of the orbital cirrus, position of the dorsal‐fin crest, taste bud number and pattern, diet, and coloration. All extant types of C. superciliosus are examined as specimens, or photographs and radiographs, and their validity and identification are assessed. Genetic analysis of mitochondrial and nuclear DNA supports species differentiation. A key is provided for the species complex. Furthermore, the variable coloration of four of the species, probably related to the substrate the larvae settle upon, and the increase in the number of vertebrae, and fin‐ray and spine number, with decreasing water temperature is discussed. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society 2012, 166 , 827–853.     

Phylogeography and diversification of an Amazonian understorey hummingbird: paraphyly and evidence for widespread cryptic speciation in the Plio‐Pleistocene

Straight‐billed Hermit Phaethornis bourcieri inhabits the understorey of upland terra firme forest throughout most of the Amazon basin. Currently, two allopatric taxa regarded as subspecies are recognized: P. b. bourcieri and P. b. major. However, the validity, interspecific limits and evolutionary history of these taxa are not yet fully elucidated. We use molecular characters to propose a phylogenetic hypothesis for populations and taxa grouped under Phaethornis bourcieri. Our results showed that P. bourcieri is part of the ‘Ametrornis’ clade, along with Phaethornis philippii and Phaethornis koepckeae, and that the subspecies major is more closely related to the latter two species than to populations grouped under nominate bourcieri. Our phylogenetic hypotheses recovered three main reciprocally monophyletic clades under nominate bourcieri separated by the lower Negro River and the Branco River or the Branco–Negro interfluve (clades B and C) and the upper Amazon (Solimões) or lower Marañon/Ucayali Rivers (clades C and D). Based on multi‐locus phylogeographic and population genetics approaches, we show that P. b. major is best treated as a separate species, and that P. b. bourcieri probably includes more than one evolutionary species, whose limits remain uncertain. The diversification of the ‘Ametrornis’ clade (P. bourcieri, P. philippii and P. koepckeae) is centred in the Amazon and appears to be closely linked to the formation of the modern Amazon drainage during the Plio‐Pleistocene.     

Detecting Altitudinal Migration Events in Neotropical Birds Using Stable Isotopes

We evaluated the utility of stable‐hydrogen isotope ratios in tropical bird tissues for detecting altitudinal migration events. Our results identified two of five species as altitudinal migrants in Nicaragua. This approach may circumvent the current limitations of mark–recapture techniques and enhance our ability to study this poorly characterized behavior.     

Open-ended song learning in a hummingbird

Vocal learning in birds is typically restricted to a sensitive period early in life, with the few exceptions reported in songbirds and parrots. Here, we present evidence of open-ended vocal learning in a hummingbird, the third avian group with vocal learning. We studied vocalizations at four leks of the long-billed hermit Phaethornis longirostris during a four-year period. Individuals produce a single song repertoire, although several song-types can coexist at a single lek. We found that nine of 49 birds recorded on multiple days (18%) changed their song-type between consecutive recordings. Three of these birds replaced song-types twice. Moreover, the earliest estimated age when song replacement occurred ranged from 186 to 547 days (mean = 307 days) and all nine birds who replaced song-types produced a crystallized song before replacement. The findings indicate that song-type replacement is distinct from an initial early learning sensitive period. As half of lekking males do not survive past the first year of life in this species, song learning may well extend throughout the lifespan. This behaviour would be convergent to vocal learning programmes found in parrots and songbirds.     

Phylogeographic patterns and cryptic speciation across oceanographic barriers in South African intertidal fishes

Biogeographic boundaries are the meeting zone of broadly distributed faunas, or the actual cause of a faunal break. In the latter case, closely related sister species should be found across such a boundary. To achieve such a situation, preliminary stages are expected, where phylogeographic breaks followed by genetic cryptic speciation would be observed. Biogeographic boundaries, in the Cape Point/Cape Agulhas region of southern Africa, offer an ideal system to test such predictions. Here, we studied two intertidal clinid fish species that are endemic to southern Africa, Clinus superciliosus (n = 127) and Muraenoclinus dorsalis (n = 114). Using mitochondrial control region, 16S rRNA, 12S rRNA and NADH2 genes and the nuclear rhodopsin and the first intron of the S7 ribosomal protein gene, we show both phylogeographic breaks and likely cryptic speciation in each species. Pairwise Φ(st) results suggest population genetic structuring for both species, with higher levels for M. dorsalis (Φ(st) = 0.34-0.93) than for C. superciliosus (Φ(st) = 0.1-0.74). Further, we recover two and three distinct lineages within M. dorsalis and C. superciliosus, respectively. Phylogenetic topologies, concordance between nuclear and mitochondrial markers and levels of sequence divergence, which are consistent with closely related sister species pairs, suggest the presence of cryptic species. Our results therefore meet the expectation for reduced gene flow at a biogeographic barrier, which translates into significant genetic breaks and cryptic sister species.     

Hummingbird responses to gender-biased nectar production: are nectar biases maintained by natural or sexual selection?

Pollinators mediate the evolution of secondary floral traits through both natural and sexual selection. Gender-biased nectar, for example, could be maintained by one or both, depending on the interactions between plants and pollinators. Here, I investigate pollinator responses to gender-biased nectar using the dichogamous herb Chrysothemis friedrichsthaliana (Gesneriaceae) which produces more nectar during the male floral phase. Previous research showed that the hummingbird pollinator Phaethornis striigularis visited male-phase flowers more often than female-phase flowers, and multiple visits benefited male more than female fecundity. If sexual selection maintains male-biased rewards, hummingbirds should prefer more-rewarding flowers independent of floral gender. If, however, differential rewards are partially maintained through natural selection, hummingbirds should respond to asymmetry with visits that reduce geitonogamy, i.e. selfing and pollen discounting. In plants with male biases, these visit types include single-flower visits and movements from low to high rewards. To test these predictions, I manipulated nectar asymmetry between pairs of real or artificial flowers on plants and recorded foraging behaviour. I also assessed maternal costs of selfing using hand pollinations. For plants with real flowers, hummingbirds preferred more-rewarding flowers and male-phase morphology, the latter possibly owing to previous experience. At artificial arrays, hummingbirds responded to extreme reward asymmetry with increased single-flower visits; however, they moved from high to low rewards more often than low to high. Finally, selfed flowers did not produce inferior seeds. In summary, sexual selection, more so than geitonogamy avoidance, maintains nectar biases in C. friedrichsthaliana, in one of the clearest examples of sexual selection in plants, to date.     

Response of a traplining hummingbird to changes in nectar availability

Theory predicts that nectarivores respond to changes in profitabilityof patches of flowers or feeders by adjusting visitation rateto increase reward size. We conducted a set of experiments inan outdoor enclosure with seven feeders to determine how Phaethornislongirostris, a traplining hummingbird, adjusts its visitationrates in response to changes in sucrose solution delivery rates.Each experiment tested the response of P. longirostris to thefollowing changes in the timing and volume of sucrose solutiondelivery: (1) increases in sucrose solution abundance at allfeeders (mimicking seasonal increases in numbers of open flowersor nectar output); (2) large changes in sucrose solution availabilityat one feeder (mimicking increases or decreases of patch profitability);and (3) sudden unexpected decreases in sucrose solution availabilityat one feeder (mimicking loss of nectar to competitors). Wefound that P. longirostris (1) decreased visitation rates whenthe sucrose solution delivery rate was higher at all feeders,(2) increased visitation rates to individual feeders when their profitabilityincreased for whole days but did not significantly decrease visitationrates when feeder output decreased; and (3) responded to sudden foodlosses at a feeder (due to simulated competition) by increasinguse of that feeder for 1 or 2 h after the loss.     

Energy regulation by traplining hummingbirds

1. A published model of constant diurnal energy accumulation by territorial hummingbirds does not accurately reflect the temporal distribution of feeding behaviour of traplining hummingbirds, Phaethornis longirostris (Long-Tailed Hermit Hummingbirds).
2. In an enclosure study, gross nectar intake by P . longirostris decreased through the day, mirroring nectar production rates in its natural food-flowers and mimicking its natural foraging patterns.
3. Using a simulation model, the energetic consequences of constant and decreasing net energy intake rates for traplining hummingbirds are compared.
4. Given natural patterns of nectar production, model birds with decreasing diurnal net intake rates met their energetic needs with fewer flowers than those with constant net intake, and spent less time foraging.
5. It is concluded that P . longirostris do not satisfy the physiological assumptions of the published model, and that in this way they are different from the territorial species on which the model has previously been tested.     

First occurrence and new length record for the bigeye thresher shark in the north-east Atlantic

The first confirmed record for the bigeye thresher shark Alopias superciliosus caught in the far north-east Atlantic is described here. The specimen was the longest and heaviest recorded to date. Above-average summer sea temperatures occurred in the catch area in 1995.     

Improved methods for color‐marking hummingbirds

ABSTRACT Individual color‐marking is an essential tool for studying the behavior of free‐living birds. Hummingbirds represent a particular challenge for traditional avian color‐marking techniques because of their small size and short tarsi. Although several techniques have been successfully used, the retention time of color‐markers and their safety and ease of construction could be improved. I developed two new color‐marking techniques for marking Little Hermits (Phaethornis longuemareus): (1) a plastic back tag constructed by fusing colored beads, and (2) a leg tag attached to a metal band fitted around the tarsus. Both tag designs were visible in field conditions, and neither appeared to adversely affect behavior. Both back and leg tags had high retention rates within seasons, but back tags had a poor retention rate between years. Although these marking techniques were designed for use on one species of hummingbird, they would likely also be useful with other species of hummingbirds.