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- Andersson, Måns Sverker, et al.
(author)
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A partly coverable badge signalling avian virus resistance
- 2006
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In: Acta Zoologica. ; :87, s. 71-76
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Journal article (peer-reviewed)abstract
- Abstract: We investigated whether the sexually selected forehead patch of the collared flycatcher Ficedula albicollis is an honest badge of status indicating quality expressed as immunological response. We used both manual measurements and digital measurements, the latter based on photographs. Badge-size data were collected during the mating period and during the nestling feeding period to capture trait plasticity. Concomitant with first sample collection, birds were inoculated with a novel antigen. Antibody response was strongly and positively correlated with badge expression during the mating period and with the increase in badge expression during the mating period as compared with outside this period. The results support the Hansen and Rohwer theory of coverable badges, are consistent with the immunocompetence handicap hypothesis and with the good genes model suggesting that, on a population level, the expression of secondary sexual traits should be an honest signal positively associated with traits that are beneficial for survival. The results also suggest that manual measurements of this type of secondary sexual trait are sufficiently exact.
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| 2. |
- Boström, Jannika E., et al.
(author)
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Ultra-Rapid Vision in Birds
- 2016
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:3
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Journal article (peer-reviewed)abstract
- Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively), which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey.
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| 3. |
- de Jong, Johnny, et al.
(author)
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Activity Pattern and Correlation between Bat and Insect Abundance at Wind Turbines in South Sweden
- 2021
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In: Animals. - : MDPI AG. - 2076-2615. ; 11
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Journal article (peer-reviewed)abstract
- Simple Summary:& nbsp;Wind power is an important energy system in the global transition towards renewable energy. As new wind farms are erected in increasing numbers, they will have an impact on many organisms, e.g., through habitat changes and collision mortalities. In this study, we measure bat activity, insect abundance, and weather conditions to test the hypothesis that insect abundance attracts bats to wind turbines because of feeding opportunities. We found that the relationship between insect abundance and bat activity was relatively weak, providing some support for the feeding-attraction hypothesis. However, we also found a strong correlation between bat passes and weather conditions. This suggests that stop-regulation based on weather conditions might be a solution to avoid collisions. However, this study highlights some of the problems with defining the limits for stop-regulation, as bat activity may be high also at relatively high wind speeds and low temperatures.& nbsp;We present data on species composition and activity of bats during two years at three different wind- turbines, located in south Sweden, both at the base and nacelle height. To test the hypothesis that bats are attracted to wind turbines because of feeding opportunities, insects were sampled at nacelle height at one wind turbine using a suction trap, simultaneously as bat activity were measured. At this wind turbine, we also compared two different technical systems for ultrasound recordings and collect meteorological data. The variation in bat activity was high between nights and between wind turbines. In addition to the expected open-air foraging species (Pipistrellus, Nyctalus, Vespertilio and Eptesicus), some individuals of unexpected species (Myotis, Barbastella, and Plecotus) were found at nacelle height. There was a weak but significant positive relation between bat activity and insect abundance, so the hypothesis could not be rejected, suggesting there might be other factors than insect abundance explaining the frequency of bat visits at the nacelle. We found a strong correlation between bat passes and weather conditions. A reasonable way to mitigate collisions is with stop-regulation. However, this study highlights some of the problems with defining the limits for stop-regulation based on weather conditions.
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| 4. |
- de Jong, Johnny, et al.
(author)
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Aktivitet av fladdermöss och insekter vid ett vindkraftverk
- 2019
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Reports (other academic/artistic)abstract
- Det är väl dokumenterat att fladdermöss kan kollidera med vindkraftverk och det är viktigt att kartlägga de bakomliggande faktorerna för att minska risken för kollisioner. Det finns ett antal hypoteser som kan förklara varför fladdermöss kan förekomma vid vindkraftverkens rotorblad. En av dessa, som testas i den här studien, är att vindkraftverken attraherar insekter, och att fladdermössen nyttjar denna resurs för födosök. För att testa hypotesen placerades en insektsfälla vid nacellen på ett vindkraftverk i Småland, tillsammans med en mikrofon som registrerar fladdermusljud. Insektsfällan var en sugfälla som endast fångade insekter under natten, och utan att attrahera insekterna. Fångst av insekter och registrering av fladdermusljud gjordes under perioden 28 juni till 3 november, 2017. Samtidigt registrerades väderleksvariabler som temperatur, vindhastighet, vindriktning och nederbörd. Registrering av fladdermöss gjordes även under perioden 1 juli till 31 oktober 2018.Resultatet visar att det finns en korrelation mellan fladdermusaktiviteten och insektsabundansen. Det finns också signifikanta korrelationer mellan fladdermusaktivitet, temperatur och vindhastighet, liksom mellan insektsabundans och vindhastighet. Den negativa korrelationen mellan antal insekter och vindhastighet var ganska stark. Övriga korrelationer är dock ganska svaga och variationen var stor både när det gäller fladdermusaktivitet och insektsabundans. Sambanden mellan fladdermusaktivitet och väderlek tycks inte vara linjära. Fladdermusaktiviteten minskar när temperaturen sjunker under 10 grader och när vindhastigheten är större än 12 m/s. Vi kan också konstatera att det inte fanns någon korrelation mellan fladdermusaktiviteten på marken och aktiviteten uppe vid nacellen. Olika fladdermustaxa hade sin maximala aktivitet vid nacellen under olika tidpunkter, men med ett visst överlapp.Resultatet från studien ger stöd åt hypotesen att fladdermössen förekommer vid nacellen av vindkraftverken för födosök, men eftersom sambandet är så svagt, och variationen så stor ligger det nära till hands att anta att det finns fler faktorer inblandade, alternativt att fladdermössen är ganska dåliga på att prediktera insektsförekomsten. Ett sätt att minska dödligheten för fladdermöss i ett konfliktområde skulle kunna vara att minska vindkraftverkens attraktion av insekter (ljud, färg, belysning mm). Ett annat sätt kan vara stoppreglering under vissa väderbetingelser, och under vissa tidsperioder. Om man väljer stoppreglering blir det viktigt att så bra som möjligt ringa in under vilka förutsättningar vindkraftverken bör stå stilla. Vår bedömning är att variationen när det gäller fladdermusförekomst och dess respons på väderfaktorer kan vara ganska stor i olika geografiska regioner och det är därför viktigt att upprepa den här typen av försök på flera platser.
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| 5. |
- Håstad, Olle, et al.
(author)
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A vision physiological estimation of ultraviolet window marking visibility to birds
- 2014
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In: PeerJ. - : PeerJ. - 2167-8359. ; 2, s. e621-
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Journal article (peer-reviewed)abstract
- Billions of birds are estimated to be killed in window collisions every year, worldwide. A popular solution to this problem may lie in marking the glass with ultraviolet reflective or absorbing patterns, which the birds, but not humans, would see. Elegant as this remedy may seem at first glance, few of its proponents have taken into consideration how stark the contrasts between ultraviolet and human visible light reflections or transmissions must be to be visible to a bird under natural conditions. Complicating matters is that diurnal birds differ strongly in how their photoreceptors absorb ultraviolet and to a lesser degree blue light. We have used a physiological model of avian colour vision to estimate the chromatic contrasts of ultraviolet markings against a natural scene reflected and transmitted by ordinary window glass. Ultraviolets markings may be clearly visible under a range of lighting conditions, but only to birds with a UVS type of ultraviolet vision, such as many passerines. To bird species with the common VS type of vision, ultraviolet markings should only be visible if they produce almost perfect ultraviolet contrasts and are viewed against a scene with low chromatic variation but high ultraviolet content.
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| 6. |
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| 9. |
- Håstad, Olle, 1971-
(author)
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Plumage Colours and the Eye of the Beholder : The Ecology of Colour and its Perception in Birds
- 2003
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Doctoral thesis (other academic/artistic)abstract
- Virtually all diurnal birds have tetrachomatic vision based on four different colour receptors. As a result, birds are potentially able to perceive their environment in twice as many colours as humans and four times as many colours compared to most other mammals, which are dichromatic. In addition to the spectrum visible to humans, birds are able to detect ultraviolet (UV) light. Signals with a UV component have been shown to be important to birds both in foraging and colour signalling. Because of the superior colour discrimination of the avian eye, UV sensitivity, but especially owing to its tetrachromacy, we cannot know what birds look like to those that matter, i.e. other birds.In my thesis I describe a new molecular method with which it is possible to identify the vision system of birds only using a small amount of DNA, without the need to keep or sacrifice the animal. It thereby facilitates large screenings, including rare and endangered species. The method has been used to increase the number of species with identified vision system type from 19 to 66. I show that raptors and songbirds have different vision systems, giving songbirds the possibility of a secret channel for colour signalling, and that male songbirds in coniferous forest take advantage of this to be significantly more cryptic to raptors than to females songbirds. I show that gulls have gained a vision system enabling them to detect the UV signals of fish when the fish swim close to the surface.Even though we tend to be rather self-satisfied with the quality of our colour vision, we are colour-blind when compared to birds. My work shows that human colour vision is inadequate for judging animal coloration, and that there is much more going on in bird colour signalling than meets our eye.
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| 10. |
- Håstad, Olle, 1971-, et al.
(author)
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Ultraviolet photopigment sensitivity and ocular media transmittance in gulls, with an evolutionary perspective
- 2009
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In: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 195:6, s. 585-590
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Journal article (peer-reviewed)abstract
- Gulls (Laridae excluding Sternidae) appear to be the only shorebirds (Charadriiformes) that have a short wavelength sensitive type 1 (SWS1) cone pigment opsin tuned to ultraviolet (UV) instead of violet. However, the apparent UV-sensitivity has only been inferred indirectly, via the interpretation that the presence of cysteine at the key amino acid position 90 in the SWS1 opsin confers UV sensitivity. Unless the cornea and the lens efficiently transmit UV to the retina, gulls might in effect be similar to violet-sensitive birds in spectral sensitivity even if they have an ultraviolet sensitive (UVS) SWS1 visual pigment. We report that the spectral transmission of the cornea and lens of great black-backed Larus marinus and herring gulls L. argentatus allow UV-sensitivity, having a λ value, 344 nm, similar to the ocular media of UV sensitive birds. By molecular sequencing of the second α-helical transmembrane region of the SWS1 opsin gene we could also infer that 15 herring gulls and 16 yellow-legged gulls L. michahellis, all base-pair identical, are genetically UV-sensitive.
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