Winter site fidelity of the Great Tit (Parus major) revealed by recaptures of individuals roosting in nest-boxes

Site fidelity during the non-breeding season is beneficial if habitat quality and environmental predictability are high. In group-living species, the costs and benefits of site fidelity may be linked to the non-social (weather) and social (dominance hierarchy) environments, but little is known about factors influencing movements during the non-breeding season. We studied both within- and between-winter site fidelity of the great tit (Parus major), a partial migrant in northern Finland. We collected mark-resight data on wintering great tits across two winters at multiple sites, and tested for the effects of age, sex, season, temperature and day length on site fidelity. Within-winter movement was lower during mid-winter and decreased during cold periods. This pattern is probably linked to energy saving and predator escaping strategies during these demanding periods when energy expenditure is high and birds have limited daylight hours to forage. Site fidelity was lower for juveniles than adults within a winter, but it was unaffected by sex. These results agree with an age related dominance structure and site-specific dominance found in great tits, but they can also be related to prior experience as young individuals still collect information during their first winter. In contrast, between-winter site fidelity was not affected by age or sex, suggesting equal benefits from site fidelity. Juveniles probably gather information on resource abundance and distribution in their first winter, and thereby gain the same benefits as adults from returning the next winter.

HABITAT USE AND WINTER SITE FIDELITY OF LINCOLN’S SPARROW (<i>MELOSPIZA LINCOLNII</i>) IN THE LOWER RIO GRANDE VALLEY OF TEXAS

Artificial light at night affects sleep behaviour differently in two closely related songbird species

Dhondt, A.A. & Adriaensen, F. 1999. Experiments on competition between Great and Blue Tit: Effects on Blue Tit reproductive success and population processes. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 70 (1): 39–48. Great Tits Parus major and Blue Tits Parus caeruleus compete for food and for cavities. By providing nest boxes with entrance holes small enough to exclude Great Tits, but allowing access to Blue Tits, either by themselves or in combination with standard nest boxes we manipulated the breeding densities of Blue and Great Tits independently. We compared populations differing in experimental densities over five-year periods. Components of Blue Tit reproductive success are adversely affected when either Blue Tit or Great Tit densities are experimentally increased. At high Blue Tit density adult survival does not change. When small-holed nest boxes are provided and Blue Tit density is increased, the number of local born males that recruit into the population increases considerably, so that the proportion of local born males is much higher than at low density. Similarly the local recruitment rate (the number of local recruits per adult breeding in the previous year) increases strongly for males, but not for females. The presence of small-holed nest boxes increases habitat quality, especially in winter when Blue Tits use these boxes for roosting, so that juveniles disperse less, and breeding density increases.

The hypothesis that late breeding entails reproductive costs to birds was tested by comparing breeding traits of control and delayed great tit Parus major clutches. In our study area, great tits and house sparrows Passer domesticus compete for nesting boxes. Since early March, nesting boxes were checked twice a week and initiated sparrow nests removed, to allow great tits to breed. 'Delayed' great tit pairs were those which, having a territory, had the nesting where they eventually bred occupied by sparrows, and therefore did not start laying until these abandoned the nesting box. Delayed pairs were assumed to be a random sample of the population. Age composition (1-year vs. older birds) and tarsus length did not differ between control and delayed birds. In 1990-92, a total of 40 pairs had their breeding delayed, while 56 acted as controls. The mean laying date of delayed pairs was at least 10 days later than controls. Delayed first clutches were smaller and took longer to hatch than controls, but mean egg volume did not differ between them. Fledging success was lower in delayed nests. Young from delayed broods were lighter at day 15 and reached a lower asymptotic weight. The mean growth rate of the nestlings was negatively related to clutch size, and differed between years, but did not differ between control and delayed broods. Control pairs were more likely to produce a second clutch, if the first one succeeded, or a replacement clutch, if the first one failed, than delayed pairs. The total production of fledglings per pair per season was higher in control pairs. Control pairs were more likely to recruit at least one young into the local breeding population than delayed pairs. However, it is not known whether late fledglings dispersed further. Our results show that delayed pairs produced fewer fledglings, of lower quality, and were less likely to recruit them into the local breeding population than controls. Therefore, the causal relationship between poor breeding performance and late breeding is supported.

Coexistence between great tits Parus major and blue tits Cyanistes caeruleus, but also other hole-nesting taxa, constitutes a classic example of species co-occurrence resulting in potential interference and exploitation competition for food and for breeding and roosting sites. However, the spatial and temporal variations in coexistence and its consequences for competition remain poorly understood. We used an extensive database on reproduction in nest boxes by great and blue tits based on 87 study plots across Europe and Northern Africa during 1957-2012 for a total of 19,075 great tit and 16,729 blue tit clutches to assess correlative evidence for a relationship between laying date and clutch size, respectively, and density consistent with effects of intraspecific and interspecific competition. In an initial set of analyses, we statistically controlled for a suite of site-specific variables. We found evidence for an effect of intraspecific competition on blue tit laying date (later laying at higher density) and clutch size (smaller clutch size at higher density), but no evidence of significant effects of intraspecific competition in great tits, nor effects of interspecific competition for either species. To further control for site-specific variation caused by a range of potentially confounding variables, we compared means and variances in laying date and clutch size of great and blue tits among three categories of difference in density between the two species. We exploited the fact that means and variances are generally positively correlated. If interspecific competition occurs, we predicted a reduction in mean and an increase in variance in clutch size in great tit and blue tit when density of heterospecifics is higher than the density of conspecifics, and for intraspecific competition, this reduction would occur when density of conspecifics is higher than the density of heterospecifics. Such comparisons of temporal patterns of means and variances revealed evidence, for both species, consistent with intraspecific competition and to a smaller extent with interspecific competition. These findings suggest that competition associated with reproductive behaviour between blue and great tits is widespread, but also varies across large spatial and temporal scales.

Reduced breeding success in nest boxes for great tits (Parus major) and Eurasian blue tits (Cyanistes caeruleus) in highly urbanised areas: An ecological trap?

We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus , breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density‐dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms.

Despite concerns about invasive Common Mynas (Acridotheres tristis), few studies have experimentally demonstrated their impact on native birds. Using a Before-After-Control-Impact (BACI) design with 142 nest boxes, we assessed how Myna presence affected House Sparrows (Passer domesticus) and Great Tits (Parus major) before (2009-2010) and after (2020-2021) their arrival in 2015. Half the boxes had large entrances accessible to all three species; half had small entrances accessible only to Great Tits. In a 2022 field experiment, we manipulated nest box entrances and used cameras to study Myna predation and nest usurpation. Following the establishment of Myna, House Sparrow breeding declined by 68.1%. Great Tits increased use of small entrance boxes by 59.9% and decreased use of large entrance boxes by 45.4%. Although overall Great Tit breeding increased, fledging success declined in large entrance boxes, but not small entrance ones. In the 2022 experiment, 46% (n = 26) of Great Tit nests were predated; Common Mynas were responsible for 50% of these cases and subsequently bred in the usurped nests. This study experimentally demonstrates that House Sparrow breeding numbers decrease and that Great Tits change their nesting behavior after the appearance of the Common Myna. Additionally, this research found that Common Mynas impact native species by predating and usurping nests. Installing small-entrance boxes can help manage Great Tit populations. Further research should explore nest box designs for House Sparrows and their impacts on other cavity-nesting and non-cavity-nesting bird species.

Spatial nest-box selection of cavity-nesting bird species in response to proximity to recreational infrastructures

The installation of nest boxes is a popular management strategy to increase nest site availability for secondary cavity-nesting birds. Standard-diameter wooden nest boxes are prone to predation, and various predator-prevention methods have therefore been developed with the intention of minimising nest box predation. However, nest box characteristics greatly affect the breeding behaviour of birds, and can therefore not only affect breeding success but are also a source of bias within the scientific literature. An initial literature review of nest box predator-prevention methods highlighted that relative to their widespread use, there is a considerable lack of research directly testing both their effectiveness and effects on breeding behaviour. A research project then showed how various life-history (e.g. brood size and nestling age) and environmental (e.g. habitat characteristics and meteorological conditions) variables affect the parental care patterns of four secondary cavity-nesting passerines (i.e., the European Pied Flycatcher (Ficedula hypoleuca), Eurasian Nuthatch (Sitta europaea), Great Tit (Parus major) and Blue Tit (Cyanistes caeruleus)) breeding in nest boxes at Nagshead Nature Reserve, a broadleaf woodland site in Gloucestershire, UK. A significant aspect of the project examined parent care behaviours in different types of nest boxes (i.e., standard, woodcrete, deep and guardian tube), aiming to test whether nest box type influences chick provisioning, a hypothesis initially proposed by Blunsden (2020). Results showed the prevalence of leaning behaviours (whereby parent birds feed nestlings by leaning into the nest chamber from the entrance hole, without having to enter fully) appeared to be an individual-specific behaviour and significantly reduced chick provisioning durations (i.e. the time taken for a bird to feed nestlings), thus having adaptive value. Although nest box type did not affect the prevalence of such behaviours, chick provisioning durations were significantly longer in woodcrete and deep nest boxes, showing these nest box types had adverse effects on a bird’s ability to effectively enter and exit the nest box to feed nestlings. Overall, although predator-prevention methods are often assumed to have a net benefit to birds, preliminary research highlights potentially unintended negative consequences that are understudied. The severity of these adverse effects is uncertain and whether the provisioning of predator-proof nest boxes provides a net benefit remains unclear.

Ectoparasites impose significant costs to their hosts and modulate their life-history traits. We evaluated the prevalence and abundance of louse flies, blowflies, fleas and mites in great tits (Parus major) and blue tits (Cyanistes caeruleus) breeding in nest boxes in Central Portugal during two consecutive breeding seasons and assessed: (a) the potential physiological consequences of infestation for nestlings; (b) how nest box re-use and presence of anthropogenic materials in nests affected the ectoparasite abundance; (c) how host reproductive parameters were related to ectoparasitism; and (d) how different nest-dwelling arthropod groups, including ectoparasites, and their diversity correlated. Tit nestlings reared in nests with more blowflies showed symptoms of anaemia, such as lower haemoglobin levels and high erythrocyte maturation index, and tended to grow less. Nestlings from nests with higher number of obligatory parasitic mites had increased polychromasia, and blue tits tended to have lower probability to fledge. Great tit nestlings from nests with fleas also had increased polychromasia compared with those from non-infested nests. Nest box re-use increased the probability of infestation by louse flies and obligatory parasitic mites. In both tit species, broods that were reared later in the season had higher abundance of blowflies and obligatory parasitic mites in their nests. In great tit nests, anthropogenic materials were negatively correlated with flea abundance, and positively correlated with the abundance of Histeridae coleopterans. In great and blue tit nests, obligatory parasitic mites were less abundant when nests showed a higher abundance of Staphylinidae coleopterans and Collembola. Overall, this study shows strong negative effects of nest ectoparasite pressure, particularly blowflies and obligatory parasitic mites, on physiological and fitness measures of hole nesting birds.

Using nest boxes with different sized entrances, we experimentally examined whether a large species of cavity breeder (House Sparrow, Passer domesticus) affects the nest box occupancy and breeding success of a smaller species (Great Tit, Parus major), and whether there are differences in the effects of competition during different parts of the breeding season. Great Tits occupied nest boxes regardless of the number of House Sparrows breeding in the vicinity. During the second part of the breeding season, the percentage of successful Great Tit pairs was negatively correlated with the occupation of nest boxes by the House Sparrows, in both the large- and small-entrance nest boxes. More Great Tit pairs bred and more young were fledged in the small- than large-entrance nest boxes. Great Tits occupied more large-entrance nest boxes during the first than the second part of the breeding season. This difference was probably due to House Sparrows occupying more large-entrance nest boxes during the second than first part of the breeding season. 74 % of the large-entrance nest boxes in which Great Tits built nests in both the first and second parts of the season were later occupied by House Sparrows. Great Tits preferred large-entrance nest boxes in the fall, when House Sparrows use only a few boxes for roosting, but not for breeding. The findings indicate that Great Tits are subject to interspecific competition with House Sparrows for nesting cavities, the intensity of which varies during the breeding season and is higher during the second part when more House Sparrows breed.

We studied use of nest boxes by Great Tits (Parus major) in rural village gardens in a semi-arid area. Great Tits occupied 46.6% of the nest boxes, and used nest boxes within higher tree densities and with more tree species in the vicinity. Breeding success was greater in nest boxes with higher plant density, more plant species, and greater height of trees in the vicinity of the nest. The presence of children or dogs (Canis lupus familiaris) near nest boxes did not affect breeding parameters. Syrian Woodpeckers (Dendrocopos syriacus) enlarged 38.0% of nest box entrances during the first year. House Sparrows (Passer domesticus) occupied 41.0% of the nest boxes with enlarged holes and none of those with normal holes. Great Tits occupied both types, but significantly fewer pairs breeding in nest boxes with enlarged holes succeeded in fledging at least one young, probably due to their eviction by the larger House Sparrows.

Rewriting The Ugly Duckling Tale: a Eurasian tree sparrow reared among great tits. Competitive relationships between hole-nesting passerine bird species can lead to mixed broods when two or more species lay their eggs in the same nest. On 5 May 2023, during a routine inspection of nest boxes in orange plantations in Sagunto, Eastern Spain, we found a Eurasian tree sparrow (Passer montanus) egg dumped among nine great tit (Parus major) eggs. From this clutch, six great tits and the Eurasian tree sparrow hatched, and four great tits and the sparrow fledged. Using a video camera inside the nest box, we observed that the nestlings, including the sparrow, were fed only by great tit adults. The adults brought caterpillars, moths and spiders, a typical great tit nestling diet in this habitat. To date, great tit eggs have been found in Eurasian tree sparrow nests, but to our knowledge this is the first report of a Eurasian tree sparrow chick successfully raised by great tits.