Eurasian Treecreeper Certhia Familiaris Research Articles

Nesting Tree Selection and Nest Characteristics of Eurasian Treecreeper Certhia familiaris at Odaesan Fir forest

Nesting Tree Selection and Nest Characteristics of Eurasian Treecreeper Certhia familiaris at Odaesan Fir forest

The Eurasian Treecreeper (Certhia familiaris) has an effective camouflage against mammalian but not avian vision in boreal forests

A well‐known example of visual camouflage in birds is the plumage coloration of the Eurasian Treecreeper Certhia familiaris, yet this species’ camouflage has never been objectively quantified. Here, we quantify Treecreeper camouflage in its boreal forest habitat, test whether Treecreepers better match tree backgrounds at nest‐site, territory or habitat spatial scales, and explore which common tree species provide the best background match. Using photographic data of the birds and forested backgrounds, we test their background match using human, ferret and avian vision modelling. We found that a Treecreeper’s wing and mantle provided the closest background matching, whereas the wing stripe and tail were more conspicuous against tree trunks. Vision modelling also suggests that Treecreeper camouflage provides a better protection against mammalian than against avian vision. The matching was not significantly different across spatial scales in local spruce forests. However, the background match was better on conifers than on deciduous trees. Our results support the long‐standing conjecture of Treecreeper camouflage but also suggest that the camouflage is an adaptation especially against mammalian predators, which are important nest predators of Treecreepers.

Single dead trees matter: Small-scale canopy gaps increase the species richness, diversity and abundance of birds breeding in a temperate deciduous forest

Canopy gaps produced by natural disturbances are an important source of structural and functional heterogeneity within forest ecosystems. However, the effect of natural, small-scale canopy gaps, caused by the mortality of a single tree or a group of trees, on bird assemblages has not been adequately addressed in temperate deciduous forests. We studied the effects of small-scale canopy gaps on the breeding birds of old-growth deciduous forests in the Carpathians (SE Poland). Our hypothesis was that such small gaps and the adjacent closed-canopy forest would differ in bird richness, diversity and relative abundance. Breeding bird assemblages were surveyed using point counts in 30 canopy gaps (mean area 301 m2 ± 228 SD, range: 37–970 m2) and in 30 control plots situated in the adjacent closed-canopy forest. The species richness, diversity and relative abundance of birds were significantly higher in the gaps than in the control plots and were correlated with the number of large snags. Collared Flycatcher Ficedula albicollis and White-backed Woodpecker Dendrocopos leucotos occurred more frequently in the gaps than in the control plots. Eurasian Treecreeper Certhia familiaris, Blackcap Sylvia atricapilla, Song Thrush Turdus philomelos and Eurasian Nuthatch Sitta europaea were more abundant in the gaps than in the control plots. The species richness of cavity- and ground-nesters was higher and these birds were more abundant in the gaps than in the control plots. The presence/absence of a gap and the number of large snags recorded in it explained 35.4% and 52.7% of the deviance in the total number of species and the total number of individual birds, respectively. Our results indicate that even small-scale canopy gaps, in combination with the large snags recorded in them resulting from the death of a single tree or group of trees, affect bird assemblages in deciduous forests as measured by the occurrence or abundance of individual species or community indices. We suggest that treefall gaps, which are heterogeneous structures, mediate the spatial distribution of bird territories within a stand and are crucial for the biodiversity of temperate deciduous forests.

Interactions between sibling species of treecreepers Certhia familiaris and C. brachydactyla in the Pyrenees and the mistaken identity hypothesis

ABSTRACT Capsule Aggressive interactions between two treecreeper species were probably the result from misidentification of heterospecifics rather than resource competition. Aims To test the alternative hypotheses that aggressive interactions between two sibling species, the Eurasian Treecreeper Certhia familiaris and the Short-toed Treecreeper Certhia brachydactyla, were the result of resource competition or misidentification of the species involved. Methods Interspecific interactions were investigated by direct observation and territory mapping of the two species during 12 years in a 25 ha plot in the Pyrenees. In addition, we performed playback experiments to test the behavioural response of both species to the heterospecific song in three sympatric areas of the Pyrenees, and in an adjacent area where only the Short-toed Treecreeper occurred. Results Territories largely overlapped between the two species. Subsequently, distance between the two species’ nearest nests was significantly shorter than distance between the same species’ nearest nests. Overall, the Short-toed Treecreeper was more aggressive towards the sibling species than the Eurasian Treecreeper. However, in contrast to what might be expected according to the resource-competition hypothesis, it was not significantly more aggressive in sympatry than in allopatry. Conclusion These results suggest that the aggressive behaviour of the Short-toed Treecreeper was mainly caused by the birds mistaking the identity of Eurasian Treecreepers, and had little impact on the cohabitation between the two species.

How generalist are these forest specialists? What Sweden’s avian indicators indicate

AbstractMonitoring of forest biodiversity and habitats is an important part of forest conservation, but due to the impossible task of monitoring all species, indicator species are frequently used. However, reliance on an incorrect indicator of valuable habitat can reduce the efficiency of conservation efforts. Birds are often used as indicators as they are charismatic, relatively easy to survey, and because we often have knowledge of their habitat and resource requirements. In the Swedish government’s environmental quality goals, there are a number of bird species identified as being associated with ‘older’ and ‘high natural value’ forests. Here we evaluate the occurrence of four of these indicator species using data from 91 production forest stands and 10 forest reserves in southern Sweden. The bird species assessed are willow titPoecile montanus, coal titPeriparus ater, European crested titLophophanes cristatusand Eurasian treecreeperCerthia familiaris. For the production stands assessed, these indicator species exhibited no significant preferences regarding forest composition and structure, indicating a wider range of habitat associations than expected. These species frequently showed territorial behavior in forest stands <60 and even 40 years of age; much younger than the 120‐year threshold for ‘older forest’ as defined by governmental environmental goals. As almost 80% of the production stands ≥10 years old included at least one of the four indicator species, this raises questions regarding the suitability of these species as indictors of forests of high conservational value in southern Sweden. Notably, besides the four species assessed here, none of the additional indicator taxa identified by the government, were recorded in the 10 reserves. This outcome may reflect the difficulties involved in finding bird indicator species indicative of high natural values in this region. Our results highlight the importance of coupling bird surveys with quantified assessments of proximate vegetation cover.

The impact of landslide stabilization on birds: Insights from an Alpine valley

Landslides are a common issue in mountains and other areas with slopes, and their frequency is increasing because of climate change. Interventions aiming at stabilizing slopes are thus common worldwide. The environmental monitoring of consequences of such interventions rarely consider the potential impacts on wild species, and especially on animal taxa. Birds are widely adopted as biological indicators thanks to their ecology and high sensitivity to environmental changes, and could represent an ideal subject also for monitoring the impacts of landslide stabilization. By monitoring birds for 8 years in a complex restoration intervention in the Italian Alps, I investigate their potential use for understanding the impacts of landslide rehabilitation at different scales, in a 350 ha-area. A BACI protocol was adopted, with bird data collected by means of point counts. Generalized linear mixed models were used to evaluate the potential impacts of restoration phases and intervention sites; analyses were developed for the breeding period and for the whole year, and for the local vs. large scale.I found evidence for different types of impacts, including the local impact of construction sites (e.g. negative for chaffinch Fringilla coelebs), of in operam phase (negative for mistle thrush Turdus viscivorus, Eurasian treecreeper Certhia familiaris and crested tit Lophophanes cristatus, positive for grey wagtail Motacilla cinerea and rock bunting Emberiza cia), as well as for a disturbance effect on species' detectability and for independent trends. The overall species richness was not (or very scarcely) affected by restoration works. This 8 yr-work provides an example of the potential efficacy of birds as indicators of the environmental impacts caused by landslide rehabilitation, which will likely become increasingly common in the next decades. Avian monitoring could helpfully be integrated within standard monitoring of environmental impacts of landslide stabilization/restoration.

Use of ‘tree tin’ nesting sites by the Eurasian Treecreeper Certhia familiaris, with notes on nest composition

ABSTRACT A corrugated bituminised roofing felt ‘tree tin’ originally provided to serve as a bat roost was adopted on a regular basis by Eurasian Treecreepers as nest sites. Data on nest construction under ‘tree tins’ are discussed.

Factors affecting the distribution of the sibling species of treecreepers Certhia familiaris and C. brachydactyla in the Pyrenees

We investigated the main environmental variables determining the occurrence of the Eurasian Treecreeper Certhia familiaris and Short-toed Treecreeper C. brachydactyla within the mountain range of the Pyrenees. Presence/absence data were obtained, using the response to the playback of each species’ typical song; they were collected during the springs of 2004–2012 over 487 sites, within 33 areas of mature forest distributed over the mountain range. The analysis, based upon generalised linear models, showed that altitude, forest type, location within the mountain range and the presence of the sibling species influenced the occurrence of both treecreepers. Probability of occurrence of the Eurasian Treecreeper increased with altitude except in mountain pine forest, whereas at a given altitude it was lower in Scots pines than in other forest types. In the Short-toed Treecreeper, whose probability of occurrence was enhanced in oak forest, the altitude had a negative influence except in mountain pine forest. In the Eurasian Treecreeper, all other things being equal, probability of occurrence was higher in the forested areas experiencing an oceanic climate than those experiencing a Mediterranean-continental climate. The opposite was found in the Short-toed Treecreeper, whose probability of occurrence on the Pyrenees’ southern slope increased from the western to the eastern end of the mountain range. Finally, the presence of the sibling species decreased the probability of occurrence of both treecreepers at low and medium altitude, suggesting a restricted form of interspecific competition.

Parental and genetic factors rather than nesting forest patch size affect physiological traits of offspring in an area‐sensitive passerine: an experimental study

Our understanding of the effects of habitat loss on individual performance is limited due to a lack of experimental studies that take the potential genetic and parental effects producing phenotypic variation into consideration. To assess the relative role of habitat loss on offspring phenotype while controlling for the confounding effects of genetic and parental variation we performed a partial cross‐fostering experiment using the Eurasian Treecreeper Certhia familiaris. The experiment was carried out by swapping half the nestlings in a brood between small and large nesting forest patches to determine the effect of nesting forest patch size on five nestling traits reflecting morphological size, body condition, physiological stress and inflammation status. There was no effect of nesting forest patch size on the offspring traits examined. Instead, we found evidence of genetic and early parental effects on all traits except inflammation status, as well as parental effects after cross‐fostering for all of the measured offspring traits. Our results suggest that genetic and parental effects should be taken into account when making inferences about species’ responses to habitat loss.

The efficiency of three-visit square surveys vs. one-visit line transects in censusing sparsely distributed birds in managed forest landscapes

SummaryWe conducted three-visit surveys of 1-km2plots and traditional Finnish single-visit line transects (considering only the 50 m wide main belt) to evaluate these methods in censusing of a predetermined set of 23 target species known to prefer old forests in three regions in Finland. The efficiency of the two methods was compared on the basis of the number of territories recorded per hour. An attempt was made to find indicators of the occurrence of suitable habitats for species preferring old forest in general, including the rarest ones, and so also largely indicating total diversity of forest bird fauna of the study area. The total number of pairs observed per hour and the abundance of sedentary bird species were significantly higher in the square surveys than in the main belt of the line transects. There were significant positive relationships between the densities of relatively abundant (density > 1.0 pairs km−2) and less abundant target species. There emerged five common forest bird species that seemed to form a suitable set of indicators of the occurrence of habitats for birds preferring old forest in the northern boreal zone: Great Spotted WoodpeckerDendrocopos major, Mistle ThrushTurdus viscivorus, Willow TitParus montanus, Eurasian TreecreeperCerthia familiaris, and Eurasian BullfinchPyrrhula pyrrhula. We concluded that sedentary species preferring old forest are good candidates for indicators to characterize some threatened aspects of forest bird diversity.

Within territory abundance of red wood ants Formica rufa is associated with the body condition of nestlings in the Eurasian treecreeper Certhia familiaris

Studies on individual reproductive success in relation to interspecific competition between distantly related taxa are scarce. We studied whether the abundance of red wood ants Formica rufa -group is related to the breeding habitat selection, fecundity and offspring quality in the Eurasian treecreeper Certhia familiaris, an old-growth forest passerine. The nest-box occupancy data were gathered over a five-year study period, whereas the breeding performance analyses were based on a two-year data set. The abundance of wood ants, measured within 50 m around the nest-boxes, was not related to nest-box occupancy rate, fecundity or the physiological stress of nestlings. In contrast, the abundance of wood ants was negatively related to the offspring quality and life-history traits, such as lowered body mass, subcutaneous fat reserves, and tarsus length at fledging. Our results suggest that exploitative competition between distantly related taxa may have considerable and adverse influences on nestling quality as measured by body mass, subcutaneous, fat and tarsus length. Red wood ants may decrease the fitness of treecreepers as the lower body condition of nestlings has the potential to impair recruitment into the breeding population and, additionally, impair the future reproductive effort.

Within territory abundance of red wood ants Formica rufa is associated with the body condition of nestlings in the Eurasian treecreeper Certhia familiaris

Within territory abundance of red wood ants Formica rufa is associated with the body condition of nestlings in the Eurasian treecreeper Certhia familiaris

Where in Europe should we look for sources of the cutaneous trematode Collyriclum faba infections in migrating birds?

Cutaneous cysts with trematodes of Collyriclum faba have been found in birds during their spring and post-breeding migrations in the Czech Republic. During spring migrations, C. faba was found in one dunnock Prunella modularis, two European robins Erithacus rubecula, three common nightingales Luscinia megarhynchos, one song thrush Turdus philomelos and one great reed warbler Acrocephalus arundinaceus. During post-breeding migration, the same parasite was found in one garden warbler Sylvia borin, one whitehroat S. communis, three goldcrests Regulus regulus and one Eurasian treecreeper Certhia familiaris. The newly identified hosts of C. faba are dunnock, common nightingale, song thrush, great reed warbler and Eurasian treecreeper. Geographical areas of the birds' infection were identified from an analysis of reports on ringed birds of the same species, the time necessary for the development of cutaneous cysts with C. faba and the time of their survival, and hitherto known geographical areas of endemic occurrence of C. faba. It is presumed that birds trapped during spring migrations were infected in some montane and submontane regions in south-western Europe (the Alps, the Apennines). Birds infected during autumn migration or post-breeding vagrancy could have been infected in the Central European Carpathians, the region of C. faba endemic occurrence. For migrating birds, the impact of C. faba infections has not been hitherto assessed.