| 1. |
- Benson, Scott A., et al.
(författare)
-
Graded-risk sensitivity in northern European mixed-species flocks of tit and nuthatch species
- 2022
-
Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 128:5, s. 437-442
-
Tidskriftsartikel (refereegranskat)abstract
- Avian species often use anti-predator calls such that the costs and benefits of vigilance are distributed within the group. Some species respond differentially to graded risk by attending to relevant predator cues, such as head orientation and gaze direction. One benefit of graded-risk sensitivity is fewer missed foraging opportunities. It is not known how the makeup of risk response behaviors in mixed-species flocks may relate to the relative nuclearity of each species in the flock. In the current study, predator models were presented to two nuclear and two satellite species of passerines that frequently occur in natural mixed flocks. Predator models either faced toward or away from a nearby stocked feeder to simulate high and low risk of predation, and calling and seed-taking rates of the present flock were recorded. The nuclear species, great tits (Parus major) and crested tits (Lophophanes cristatus), took more seeds when the predator faced away from the feeder than toward it. The satellite species, Eurasian nuthatches (Sitta europaea) and willow tits (Poecile montanus), did not show an effect of predator orientation. No species showed consistent differences in calling behavior relative to predator orientation, although insufficient calling data for great tits prevented analysis for this species. The results of this study suggest that one aspect of nuclearity in mixed-species flocks is a tendency for graded-risk sensitivity, or alternatively, that satellite species are more sensitive to mere predator presence rather than to predator orientation cues.
|
|
| 2. |
|
|
| 3. |
- Eeva, Tapio, et al.
(författare)
-
Geographical trends in the yolk carotenoid composition of the pied flycatcher (Ficedula hypoleuca)
- 2011
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 165:2, s. 277-287
-
Tidskriftsartikel (refereegranskat)abstract
- Carotenoids in the egg yolks of birds are considered to be important antioxidants and immune stimulants during the rapid growth of embryos. Yolk carotenoid composition is strongly affected by the carotenoid composition of the female's diet at the time of egg formation. Spatial and temporal differences in carotenoid availability may thus be reflected in yolk concentrations. To assess whether yolk carotenoid concentrations or carotenoid profiles show any large-scale geographical trends or differences among habitats, we collected yolk samples from 16 European populations of the pied flycatcher, Ficedula hypoleuca. We found that the concentrations and proportions of lutein and some other xanthophylls in the egg yolks decreased from Central Europe northwards. The most southern population (which is also the one found at the highest altitude) also showed relatively low carotenoid levels. Concentrations of beta-carotene and zeaxanthin did not show any obvious geographical gradients. Egg yolks also contained proportionally more lutein and other xanthophylls in deciduous than in mixed or coniferous habitats. We suggest that latitudinal gradients in lutein and xanthophylls reflect the lower availability of lutein-rich food items in the northern F. hypoleuca populations and in montane southern populations, which start egg-laying earlier relative to tree phenology than the Central European populations. Similarly, among-habitat variation is likely to reflect the better availability of lutein-rich food in deciduous forests. Our study is the first to indicate that the concentration and profile of yolk carotenoids may show large-scale spatial variation among populations in different parts of the species' geographical range. Further studies are needed to test the fitness effects of this geographical variation.
|
|
| 4. |
- Freeberg, Todd M., et al.
(författare)
-
Tufted titmouse (Baeolophus bicolor) calling and risk-sensitive foraging in the face of threat
- 2014
-
Ingår i: Animal Cognition. - : Springer Science and Business Media LLC. - 1435-9448 .- 1435-9456. ; 17:6, s. 1341-1352
-
Tidskriftsartikel (refereegranskat)abstract
- Individuals often produce alarm or mobbing calls when they detect a threat such as a predator. Little is known about whether such calling is affected by the facial orientation of a potential threat, however. We tested for an effect of facial orientation of a potential threat on tufted titmice, Baeolophus bicolor, a songbird that uses chick-a-dee calls in a variety of social contexts. In two studies, a human observer wore an animal mask that either faced or faced away from the focal bird(s). In Study 1, focal birds were individual titmice captured in a walk-in trap, and the observer stood near the trapped bird. In Study 2, focal birds were titmouse flocks utilizing a feeding station and the observer stood near the station. In both studies, calling behavior was affected by mask orientation. In Study 2, foraging and agonistic behavior were also affected. Titmice can therefore perceive the facial orientation of a potential threat, and this perception affects different behavioral systems, including calling. Our results indicate sensitivity of titmice to the facial orientation of a potential predator in two quite different motivational contexts. This work suggests the possibility of strategic signaling by prey species depending upon the perceptual space of a detected predator.
|
|
| 5. |
- Krama, Tatjana, et al.
(författare)
-
You mob my owl, I'll mob yours : birds play tit-for-tat game
- 2012
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 2
-
Tidskriftsartikel (refereegranskat)abstract
- Reciprocity is fundamental to cooperative behaviour and has been verified in theoretical models. However, there is still limited experimental evidence for reciprocity in non-primate species. Our results more decisively clarify that reciprocity with a tit-for-tat enforcement strategy can occur among breeding pied flycatchers Ficedula hypoleuca separate from considerations of byproduct mutualism. Breeding pairs living in close proximity (20-24 m) did exhibit byproduct mutualism and always assisted in mobbing regardless of their neighbours' prior actions. However, breeding pairs with distant neighbours (69-84 m) either assisted or refused to assist in mobbing a predatory owl based on whether or not the distant pair had previously helped them in their own nest defense against the predator. Clearly, these birds are aware of their specific spatial security context, remember their neighbours' prior behaviour, and choose a situation-specific strategic course of action, which could promote their longer-term security, a capacity previously thought unique to primates.
|
|
| 6. |
- Krams, Indrikis, et al.
(författare)
-
Linking social complexity and vocal complexity : a parid perspective
- 2012
-
Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 367:1597, s. 1879-1891
-
Forskningsöversikt (refereegranskat)abstract
- The Paridae family (chickadees, tits and titmice) is an interesting avian group in that species vary in important aspects of their social structure and many species have large and complex vocal repertoires. For this reason, parids represent an important set of species for testing the social complexity hypothesis for vocal communication-the notion that as groups increase in social complexity, there is a need for increased vocal complexity. Here, we describe the hypothesis and some of the early evidence that supported the hypothesis. Next, we review literature on social complexity and on vocal complexity in parids, and describe some of the studies that have made explicit tests of the social complexity hypothesis in one parid-Carolina chickadees, Poecile carolinensis. We conclude with a discussion, primarily from a parid perspective, of the benefits and costs of grouping and of physiological factors that might mediate the relationship between social complexity and changes in signalling behaviour.
|
|
| 7. |
- Krams, Indrikis, et al.
(författare)
-
Nocturnal loss of body reserves reveals high survival risk for subordinate great tits wintering at extremely low ambient temperatures
- 2013
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 172:2, s. 339-346
-
Tidskriftsartikel (refereegranskat)abstract
- Winter acclimatization in birds is a complex of several strategies based on metabolic adjustment accompanied by long-term management of resources such as fattening. However, wintering birds often maintain fat reserves below their physiological capacity, suggesting a cost involved with excessive levels of reserves. We studied body reserves of roosting great tits in relation to their dominance status under two contrasting temperature regimes to see whether individuals are capable of optimizing their survival strategies under extreme environmental conditions. We predicted less pronounced loss of body mass and body condition and lower rates of overnight mortality in dominant great tits at both mild and extremely low ambient temperatures, when ambient temperature dropped down to −43 °C. The results showed that dominant great tits consistently maintained lower reserve levels than subordinates regardless of ambient temperature. However, dominants responded to the rising risk of starvation under low temperatures by increasing their body reserves, whereas subdominant birds decreased reserve levels in harsh conditions. Yet, their losses of body mass and body reserves were always lower than in subordinate birds. None of the dominant great tits were found dead, while five young females and one adult female were found dead in nest boxes during cold spells when ambient temperatures dropped down to −43 °C. The dead great tits lost up to 23.83 % of their evening body mass during cold nights while surviving individuals lost on average 12.78 % of their evening body mass. Our results show that fattening strategies of great tits reflect an adaptive role of winter fattening which is sensitive to changes in ambient temperatures and differs among individuals of different social ranks.
|
|
| 8. |
- Lehtonen, Paula K., et al.
(författare)
-
Geographic patterns of genetic differentiation and plumage colour variation are different in the pied flycatcher (Ficedula hypoleuca)
- 2009
-
Ingår i: Molecular Ecology. - 0962-1083. ; 18:21, s. 4463-4476
-
Tidskriftsartikel (refereegranskat)abstract
- The pied flycatcher is one of the most phenotypically variable bird species in Europe. The geographic variation in phenotypes has often been attributed to spatial variation in selection regimes that is associated with the presence or absence of the congeneric collared flycatcher. Spatial variation in phenotypes could however also be generated by spatially restricted gene flow and genetic drift. We examined the genetic population structure of pied flycatchers across the breeding range and applied the phenotypic Q(ST) (P(ST))-F(ST) approach to detect indirect signals of divergent selection on dorsal plumage colouration in pied flycatcher males. Allelic frequencies at neutral markers were found to significantly differ among populations breeding in central and southern Europe whereas northerly breeding pied flycatchers were found to be one apparently panmictic group of individuals. Pairwise differences between phenotypic (P(ST)) and neutral genetic distances (F(ST)) were positively correlated after removing the most differentiated Spanish and Swiss populations from the analysis, suggesting that genetic drift may have contributed to the observed phenotypic differentiation in some parts of the pied flycatcher breeding range. Differentiation in dorsal plumage colouration however greatly exceeded that observed at neutral genetic markers, which indicates that the observed pattern of phenotypic differentiation is unlikely to be solely maintained by restricted gene flow and genetic drift.
|
|
| 9. |
- Moller, Anders Pape, et al.
(författare)
-
Clutch-size variation in Western Palaearctic secondary hole-nesting passerine birds in relation to nest box design
- 2014
-
Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 5:4, s. 353-362
-
Tidskriftsartikel (refereegranskat)abstract
- Secondary hole-nesting birds that do not construct nest holes themselves and hence regularly breed in nest boxes constitute important model systems for field studies in many biological disciplines with hundreds of scientists and amateurs involved. Those research groups are spread over wide geographic areas that experience considerable variation in environmental conditions, and researchers provide nest boxes of varying designs that may inadvertently introduce spatial and temporal variation in reproductive parameters. We quantified the relationship between mean clutch size and nest box size and material after controlling for a range of environmental variables in four of the most widely used model species in the Western Palaearctic: great tit Parus major, blue tit Cyanistes caeruleus, pied flycatcher Ficedula hypoleuca and collared flycatcher F.albicollis from 365 populations and 79610 clutches. Nest floor area and nest box material varied non-randomly across latitudes and longitudes, showing that scientists did not adopt a random box design. Clutch size increased with nest floor area in great tits, but not in blue tits and flycatchers. Clutch size of blue tits was larger in wooden than in concrete nest boxes. These findings demonstrate that the size of nest boxes and material used to construct nest boxes can differentially affect clutch size in different species. The findings also suggest that the nest box design may affect not only focal species, but also indirectly other species through the effects of nest box design on productivity and therefore potentially population density and hence interspecific competition.
|
|
| 10. |
- Moller, Anders P., et al.
(författare)
-
Variation in clutch size in relation to nest size in birds
- 2014
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:18, s. 3583-3595
-
Tidskriftsartikel (refereegranskat)abstract
- Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose nest sites and to build optimally sized nests, yet our current understanding of clutch size-nest size relationships is limited to small-scale studies performed over short time periods. Here, we quantified the relationship between clutch size and nest size, using an exhaustive database of 116 slope estimates based on 17,472 nests of 21 species of hole and non-hole-nesting birds. There was a significant, positive relationship between clutch size and the base area of the nest box or the nest, and this relationship did not differ significantly between open nesting and hole-nesting species. The slope of the relationship showed significant intraspecific and interspecific heterogeneity among four species of secondary hole-nesting species, but also among all 116 slope estimates. The estimated relationship between clutch size and nest box base area in study sites with more than a single size of nest box was not significantly different from the relationship using studies with only a single size of nest box. The slope of the relationship between clutch size and nest base area in different species of birds was significantly negatively related to minimum base area, and less so to maximum base area in a given study. These findings are consistent with the hypothesis that bird species have a general reaction norm reflecting the relationship between nest size and clutch size. Further, they suggest that scientists may influence the clutch size decisions of hole-nesting birds through the provisioning of nest boxes of varying sizes.
|
|
