Advanced breeding dates in relation to recent climate warming in a Mediterranean montane population of Blue Tits Cyanistes caeruleus

Trends in the onset of breeding, clutch size and numbers of hatchlings and fledglings are examined for a Mediterranean montane population of Blue Tits (Cyanistes caeruleus) subject to recent warming in springtime monitored during 20 years. Blue Tits advanced their breeding dates in relation to mean air temperatures in April and, as a consequence, laid larger clutches. However, increases in the numbers of hatchlings and fledged young over time were not statistically significant after accounting for variables of influence. The entire breeding season seems to have been displaced towards earlier dates by adjusting breeding time to increased temperatures in prebreeding time, to which Blue Tits have been more responsive than Pied Flycatchers (Ficedula hypoleuca) in the same area. The alternative hypothesis, that interference competition with Pied Flycatchers for nestboxes and caterpillars, the main common food base of nestlings, has been the driving force behind the advancement of laying of the Blue Tit population, was not supported. However, the significant advance of breeding dates in Blue Tits has not been sufficient to overcome the precipitous decline in reproductive fitness with the advancement of the season.     

Why do Corsican Blue Tits Cyanistes caeruleus ogliastrae not use nest boxes for roosting?

We compared winter roosting behaviour of Blue Tits Cyanistes caeruleus in the mainland of southern France and on the island of Corsica in small-holed nest boxes. While in southern France Blue Tits use nest boxes for roosting, Corsican Blue Tits do not. We suggest that this behaviour is innate because Corsican wild-caught as well as F1 and F2 birds born in captivity do not use nest boxes in aviaries even when kept adjacent to mainland tits that sleep in boxes. We suggest that the cost/benefit balance differs between mainland France and Corsica: in Corsica, the costs of roosting in the canopy are less than in mainland France because (1) predators, e.g. owls, are rare in Corsica while abundant on the mainland, (2) the permanent evergreen foliage of the dominant tree in Corsica, the holm oak, could be preferred to nest boxes which are not risk-free, and (3) the costs of using cavities for roosting could be higher in Corsica because of increased mammal predator pressure and higher ectoparasite load than on the mainland.     

Territorial responses of male blue tits, Cyanistes caeruleus , to UV-manipulated neighbours

Multiple phenotypic traits can affect the outcome of interactions among territorial animals. Individuals may use current and previously acquired information on phenotypic traits to assess the competitive ability of opponents and adjust the strength of their response depending on the threat the opponent poses. In birds, colourful plumage and song are widespread phenotypic traits. Recent work has shown that ultraviolet (UV) plumage reflectance may be used by males in assessing an opponent’s strength and by females in mate choice. In the present study, we investigated whether and how territorial male blue tits, Cyanistes caeruleus, use previously acquired information from UV reflectance of the crown feathers of neighbours to adjust their response to playback of song of these neighbours simulated to intrude their territory. We compared responses to neighbours with those to unfamiliar strangers with unknown plumage features. We found that subject males with UV-enhanced neighbours responded more strongly to these neighbours than to strangers, i.e. showed more flights, used songs without trill and tended to overlap more songs. Subject males with UV-reduced neighbours gave a lower or similar response to neighbours compared to strangers. This indicates that male blue tits combine previously acquired information about an intruder’s plumage with familiarity of its song, and that their response depends on the perceived quality of the neighbour. This study provides evidence that familiarity in combination with multiple signals of quality may influence territorial relations among neighbours.     

Within-season divorce in Common Terns Sterna hirundo in a year of heavy predation

Divorce between seasons is a common phenomenon in seabirds, whereas within-season mate change is rarely observed. We report four cases of within-season mate change in renesting Common Terns Sterna hirundo during a year of heavy predation by a Long-eared Owl Asio otus, when we found more deserted clutches, lower hatching success as well as more disappeared chicks compared to other years. Within-season nest-site fidelity also decreased under predation pressure.     

Implications of conspecific background noise for features of blue tit, Cyanistes caeruleus , communication networks at dawn

Communication among animals often comprises several signallers and receivers within the signal’s transmission range. In such communication networks, individuals can extract information about differences in relative performance of conspecifics by eavesdropping on their signalling interactions. In songbirds, information can be encoded in the timing of signals, which either alternate or overlap, and both male and female receivers may utilise this information when engaging in territorial interactions or making reproductive decisions, respectively. We investigated how conspecific background noise at dawn may overlay and possibly constrain the perception of such singing patterns. We simulated a small communication network of blue tits, Cyanistes caeruleus, at dawn in spring. Two loudspeakers simulated a singing interaction which was recorded from four different receiver positions simulating potential eavesdroppers. During the recordings, resident blue tit males were vocalising and created natural conspecific background noise. Levels of conspecific background noise were high and varied among positions of potential eavesdroppers. We conclude that conspecific background vocalisations may potentially constrain the perception of singing patterns and may constitute costs for eavesdroppers. On the other hand, signallers may position themselves strategically and privatise their interactions.     

Relationship between temperature and the timing of breeding of the Blue Tit (Parus caeruleus) in two Mediterranean oakwoods

Summary Correlations between warmth sum and egg laying in tits (Paridae) were often found but do not prove that there is a direct influence of temperature on egg laying date. Such correlations are also open to criticism because they involve a statistical bias (i. e. the selection of variables). Studies of a Blue Tit population in two close but different habitats in Mediterranean France showed that it is better, at least, to consider a time period with a physiological signification (1 January–10 April). We found that the higher the mean temperature in this time period, the earlier the egg laying commenced. Egg laying dates of the Blue Tit in the two habitats are primarily attributed to habitat-related feeding resources.

---

Zusammenfassung Die zahlreich publizierten Korrelationen zwischen Wärmesummen und Beginn der jährlichen Legeperiode bei Meisen (Paridae), bilden keinen Beweis für einen direkten Einfluß der Temperatur auf den Legebeginn. Solche Korrelationnen beruhen außerdem auf statistische fraglichen Auswertungen. Untersuchungen an einer Blaumeisenpopulation (Parus caeruleus) in zwei benachbarten, aber verschiedenen Bruthabitaten im mediterranen Südfrankreich zeigten, daß höchstens ein längerer Zeitabschnitt (1. Januar bis 10. April) mit physiologischer Bedeutung in Betracht zu ziehen ist. Je höher die Durchschnittstemperatur in dieser Periode, um so früher der Legebeginn, der jedoch hauptsächlich durch die zeitlich unterschiedlichen Nahrungsangebote in den beiden untersuchten Habitaten erklärt wird.

     

Experimentelle Untersuchungen zur Brutbiologie von Kohl- und Blaumeise (Parus major undP. caeruleus)

Zusammenfassung 1. Für die vorliegende Arbeit wurden Untersuchungsbefunde aus dem Jahr 1969 an 53 Kohlmeisen- und 39 Blaumeisen-Erstbruten eines Laubwaldgebietes bei Braunschweig ausgewertet.2. Blaumeisen begannen gesichert um 2 1/2 Tage früher mit der Eiablage als Kohlmeisen. Zwischen den Altersstufen einer Art konnten dagegen keine Unterschiede festgestellt werden.3. Unterbrechungen in der Eifolge bei Kohl- und Blaumeise wurden möglicherweise durch Temperaturstürze hervorgerufen.4. Die intraindividuelle Variabilität der Eidimensionen (Eilänge, Eibreite und kalkuliertes Eivolumen) war stets signifikant geringer als die interindividuelle Variabilität. Für Eibreite und Eilänge ergab sich bei beiden Arten eine positive Korrelation.5. Einjährige Kohlmeisen legten gesichert längere und breitere Eier als mehrjährige Tiere; bei der Blaumeise konnten in der Eigröße keine diesbezüglichen Unterschiede festgestellt werden.6. Bruten mit mittelgroßer Eizahl wiesen bei beiden Arten im Durchschnitt die größten Eier auf. Innerhalb eines Geleges waren in der Regel die zuletzt gelegten Eier größer als die zuerst gelegten.7. Fortnahme bzw. Hinzulegen von Eiern während der individuellen Legeperiode hatte bei den Weibchen eine gesichert höhere bzw. niedrigere Eiproduktion im Vergleich zu einer Kontrollgruppe zur Folge. Kohl- und Blaumeisen sind somit als indeterminierte Leger zu bezeichnen.8. Die durchschnittliche Brutdauer betrug bei der Kohlmeise 13,9 und bei der Blaumeise 14,6 Tage.9. Die Reihenfolge des Schlüpfens war bei den zuerst gelegten Eiern häufiger unregelmäßig.10. Nestlinge großer Bruten waren bei beiden Arten leichter als gleichalte Junge kleiner Bruten.11. Die Nestlingsdauer betrug im Durchschnitt bei der Kohlmeise 18,8 und bei der Blaumeise 19,9 Tage. Zwischen verschieden großen Bruten konnte kein Unterschied in der Nestlingsdauer festgestellt werden.

---

Summary 1. In 1969, 53 first broods of Great Tits and 39 first broods of Blue Tits were studied in mixed deciduous woodland near Brunswick.2. On the avarage Blue Tits laid significantly (2 1/2 days) earlier than Great Tits. No differences could be found in the date of laying between different age groups within a species.3. In both species, a drop in temperature may possible cause a 1–2 days' interruption in laying.4. There was significantly less variation among different eggs (length, breadth, and calculated volume) laid by the same bird than among the average egg characteristics of different birds. In both species, there was a positive correlation between length and breadth of the egg.5. Avarage breadth and length of eggs were significantly bigger in one-year old Great Tits than in older birds. Such differences did not exsist in Blue Tits.6. Eggs from avarage-sized clutches were bigger than those from very small or very large clutches. As a rule, the last egg of a clutch were bigger than the first ones.7. Compared with the clutch size of a controll group, daily removal of eggs or addition of eggs. — soon after the onset laying — resulted in an increase or in a reduction of the clutch size, respectively. Consequently, Great and Blue Tit may be considered as indeterminate layers.8. The mean incubation period of the Great Tit was found to be 13,9 days, that of the Blue Tit 14,6 days.9. The first eggs of a clutch frequently did not hatch in the order they were laid.10. In both species, nestlings of large-sized broods avaraged lighter than nestlings of smaller-sized broods.11. The mean nestling period of the Great Tit was found to be 18,8 days, that of the Blue Tit 19,9 days. There was no difference between the nestling period in large and small broods.

---

---

Herrn Dr. Rudolf Berndt zum 60. Geburtstag in Dankbarkeit gewidmet

---

Erweiterte Fassung eines am 10. 10. 1969 auf der 82. Jahresversammlung der Deutschen Ornithologen-Gesellschaft in Münster gehaltenen Vortrages. Materialsammlung und -auswertung erfolgten mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Zur Populationsdynamik der Blaumeise (Parus caeruleus): Langfristige Studien bei Braunschweig

Zusammenfassung Von 1957–1990 blieb der Brutbestand der Blaumeise in 3 Kontrollgebieten (Flächengröße insgesamt 370 ha) gleich, doch ergaben sich beträchtliche jährliche Fluktuationen. Männliche Brutvögel hatten ein signifikant höheres Durchschnittsalter (2,01±0,04 Jahre) als weibliche (1,72±0,03 Jahre). Die danach ermittelte Mortalität beträgt 50 % () bzw. 58 % (). Im Durchschnitt siedelten gesichert näher am Geburtsort als ( =365 bzw. 700 m). Als maximale Ansiedlungsentfernung konnten 24 km () bzw. 470 km () nachgewiesen werden. Auch die Ortswechsel zwischen Bruthöhlen verschiedener Jahre waren bei gesichert geringer als bei ( =40 bzw. 75 m). Die weitesten Brutumsiedlungen fanden über 0,75 km () bzw. 37 km () statt. Emigration über >5 km vom Geburtsort wurde für maximal 4,2 der Nestlinge nachgewiesen. Abwanderungen vom Geburtsort über große Distanzen (>100 km) erfolgten bevorzugt nach WSW (mittlerer Vektor: 241,5°). Zwischen Brutpaardichte und dem -Wert der Zufallsfunde im 1. Lebensjahr (>5 km vom Geburstort) besteht von 1960–1989 ein gesichert positiver Zusammenhang. Seit 1976 konnte jedoch selbst in Jahren mit Bestandsspitzen keine überdurchschnittliche Emigration mehr festgestellt werden. Die Rückmelderate (alle Funde >5 km vom Geburtsort) nahm von 1960–1989 signifikant ab.

---

Population dynamics of the Blue Tit (Parus caeruleus): Longterm investigations in the Braunschweig region

Summary In more than 20 study areas, spread over approximately 1200 km² near Braunschweig (52.16 N 10.32 E), the population dynamics of Blue Tits breeding in nestboxes has been studied. In three study areas (circa 370 ha overall) no significant long term trend was recognisable from 1957 to 1990. There were, however, considerable fluctuations in the particular years.Males had a significantly higher average age (2,01±0,04 years) than females (1,72±0,03 years). Accordingly the mortality rate of adult Blue Tits amounted to 50 % () and 58 % (). On average males settled significantly nearer from their birth place than females (median values: 365 and 700 m). Maximum distances of 24 km () and 470 km () were recorded. Change of locality between nestboxes of different years was significantly smaller for males than for females (median values: 40 and 75 m). The farthest breeding resettlement was in distances of 0,75 km () and 37 km ().Emigration over more than 5 km from birth place was established for a maximum of 4,2 of all Blue Tit nestlings of a particular years. Migrations over distances >100 km from birth place to recovery area were predominantly in WSW (average vector: 241,5°). There is a significantly positive relationship between the breeding-pair density of Blue Tits and the -rate of chance recoveries (more than 5 km from birth place during first year of life) of the years 1960 to 1989. Since 1976, however, above average emigration — even in years of peak populations — could not be established. The rate of recovery (all findings more than 5 km from birth place) declined significantly in the years 1960 to 1989.

     

Zur Farbpr?ferenz vonParus major undP. caeruleus

Ohne Zusammenfassung     

Legefolge und asynchrones Schlüpfen bei Tannen- und Blaumeise (Parus ater,P. caeruleus)

Zusammenfassung Untersuchungen über den Zusammenhang zwischen Legefolge der Eier und Schlüpffolge der Jungen von Tannen- und Blaumeisen erbrachten für die beobachteten Bruten starke Korrelationen für alle Eier eines Geleges. Die biologische Bedeutung des asynchronen Schlüpfens von Meisen ist noch nicht eindeutig geklärt, weitere Studien erscheinen angebracht.

---

Laying sequence and hatching asynchrony in Coal and Blue Tit (Parus ater,P. caeruleus)

Summary During a long-term study at the Alpenzoo Innsbruck/Tyrol on behaviour and ecology of tits (Parus) selected broods of Coal and Blue Tit were thoroughly checked during the hatching period in 1988 and 1989. The exact sequence of hatching could be determined by two nest controls per hour. Highly significant correlations between sequence of laying and hatching could be found within the whole clutch. The consequences of this laying-dependent hatching asynchrony are not yet fully understood, although as much as eight hypothesis try to explain its biological significance. Further investigations, both long-term and experimental studies, will be necessary to understand adaptive strategies in tits.

     

Versuche zum angenommenen Kontrastverlust im Gesang der Blaumeise (Parus caeruleus) auf Teneriffa

Zusammenfassung Der Gesang von Blaumeisen-Populationen in Mitteleuropa, Spanien, Marokko und auf Teneriffa wurde miteinander verglichen (Abb. 1). In Süddeutschland und auf Teneriffa wurden Klang-Attrappen-Versuche durchgeführt.1. Der Blaumeisen-Gesang ist in Marokko und auf Teneriffa sehr ähnlich. Er unterscheidet sich vom Blaumeisengesang in Europa (Mitteleuropa und Spanien) in folgenden Eigenschaften (2.–4.):2. Ihm fehlen phrasierte Strophen (Abb. 2 a–c, e, 3, 4 a, b, f, g), also Strophen, in denen dasselbe Element mindestens viermal nacheinander wiederholt wird.3. Er enthält mehr verschiedene Elemente (Abb. 5, 7).4. Die interindividuelle Variation ist größer (Abb. 6, 7).5. Die Unterschiede zwischen dem Blaumeisen-Gesang in Europa und auf Teneriffa lassen sich nicht mit der Kontrast-Betonungs- und der Kontrast-Verlust-Hypothese nachLack &Southern (1949) undMarler (1960) erklären. Die Lernentzugs-Hypothese erklärt sie besser.6. Die Blaumeisen von Teneriffa und Marokko sind sehr nahe miteinander verwandt, aber vermutlich sind sie von den europäischen Blaumeisen artlich nicht getrennt.

---

The song of the Blue Tit (Parus caeruleus) on Tenerife: Experiments on a presumed loss of contrast

Summary Songs of Blue Tit populations from Central Europe, Spain, Morocco and Tenerife (fig. 1) were compared. Playback experiments were made in South Germany and on Tenerife.1. Blue Tit songs from Morocco and Tenerife are very similar. They differ from songs of Blue Tits in Europe (Central Europe and Spain) in the following characteristics (2–4):2. Lack of phrased songs (fig. 2 a–c, e, 3, 4 a, b, f, g), i. e. songs with the same notes repeated successively at least four times.3. A greater number of different types of notes (fig. 5, 7).4. Greater interindividual variation (fig. 6, 7).5. Differences between Blue Tit song from Europe and from Tenerife cannot be explained by the hypothesis of contrast reinforcement and loss of contrast, according toLack &Southern (1949) andMarler (1960). The withdrawal of learning hypothesis is a better explanation.6. Blue Tits on Tenerife and Morocco are very closely related to each other but are probably not a different species from the Blue Tits of Europe.

---

---

Für die Übersetzung danken wir FrauR. Jellis und HerrnP. Lundberg.     

Personality in Blue Tits (Cyanistes caeruleus) and its Effect on Their Breeding Success

In this study, we investigated whether blue tits (Cyanistes caeruleus) showed consistent variation in neophobia responses. The experiment represents a test of how personality, consistent individual differences in behaviour, may have fitness consequences. The experimental design consisted of a control observation followed by two neophobia tests, during which the parent's behaviour was recorded using the instantaneous sampling method. Blue tits showed consistent variation in neophobia responses, which was related to total offspring biomass, but not to mean offspring weight or fledging success. General linear mixed models analyses suggest that there may be ideal neophobia trait combinations in breeding pairs that maximise breeding success.     

Dominance and anti-predator behaviour in blue tits (Parus caeruleus)

Evidence from captive flocks of blue tits (Parus caeruleus) suggests that following the appearance of a predator, socially dominant individuals are likely to wait until subordinate members of their flock resume feeding before doing so themselves. After a model sparrowhawk (Accipiter nisus) was flown over captive flocks of blue tits at a feeder, there was a significant negative correlation between sequence of return to the feeder and status within a linear dominance hierarchy. During this period, birds increased the proportion of their time budgets devoted to scanning for predators. These results suggest that during periods of danger, high-ranking individuals are able to be more cautious than are low-ranking individuals, possibly because their ability to control food resources reduces the energetic costs of their extra caution.     

Breeding biology of the Blue TitParus caeruleus in a montane mediterranean deciduous forest: the interaction of latitude and altitude

Laying date and clutch size in a population of the Blue Tit were evaluated during five years in a montane deciduous oak forest central Spain. By comparison with other Mediterranean and non-Mediterranean Blue Tit populations in the same habitat type of the Palearctic region, we found a similar timing of breeding than in central and North European populations. However, the low clutch size is in agreement with the latitudinal tendency in clutch size observed byLack (1947, 1966). The relatively altitude constraining the distribution of this habitat type may affect the delayed breeding season and low average clutch size observed. The degree of isolation of this habitat type in the Spanish Central Range, and the gene flow of Blue Tits populations setting in bordering habitats of poorer quality, may also contribute to the smaller clutch size observed in our study population.

---

Zusammenfassung In einem montanen Wald aus laubwerfenden Eichen in Zentralspanien wurden in fünf Jahren Legebeginn und Gelegegröße einer Blaumeisenpopulation untersucht. Im Vergleich mit anderen mediterranen und nicht-mediterranen Population desselben Habitattyps der Paläarktis ergaben sich ähnliche Brutzeitdaten in Nordeuropa. Die niedrige Gelegegröße steht jedoch in Übereinstimmung mit einer breitenparallelen Tendenz (vgl.Lack 1947, 1966). Die relative Seehöhe, die die Ausdehung des Habitats begrenzt, könnte einen Einfluß auf den festgestellten späten Legebeginn und die niedrige Gelegegröße haben. Darüberhinaus könnte auch die isolierte Lage des Habitattyps in der spanischen Zentralkordillere und der Genfluß zwischen Blaumeisen in Grenzarealen geringerer Qualität zur niedrigeren Gelegegröße in der untersuchten Population beigetragen haben.

     

Extrapair paternity in insular African Blue Tits Cyanistes teneriffae is no less frequent than in continental Eurasian Blue Tits Cyanistes caeruleus

Birds breeding on islands often exhibit lower rates of extrapair paternity than their mainland counterparts, perhaps explained by low genetic variation, ‘slower’ life histories and reduced sexual selection in island populations. Extrapair paternity was apparent in 39% (12/19) of broods, and encompassed 15% (21/137) of nestlings, in a population of African Blue Tits Cyanistes teneriffae, in Tenerife, Canary Islands. There were no cases of intraspecific brood parasitism. The incidence of extrapair young lies in the upper range of that reported from mainland populations of the closely related Eurasian Blue Tit Cyanistes caeruleus. We conclude that there is no strong island effect on the genetic mating system in the Cyanistes species group but that extrapair paternity rates in Cyanistes are greater at southern latitudes.     

Variation in the magnitude of sexual size dimorphism in nestling Coal Tits (Periparus ater)

The magnitude of sexual size dimorphism can be affected by sex differences in environmental sensitivity early in ontogeny that result in differential growth rates of male and female nestlings. Here, the larger sex might either be more sensitive because of higher food demands or less sensitive due to greater competitive ability. When environmental conditions deteriorate during the breeding season, this “environmental stress” hypothesis predicts differential seasonal declines in the performance of male and female offspring. Based on a sample of molecularly sexed Coal Tit (Periparus ater) nestlings from 2 years, we investigated sexual size dimorphism in body mass, condition (i.e. size-corrected mass), tarsus and wing length and whether its magnitude changed from early to late broods. Male offspring were heavier, larger (in terms of tarsus and wing length) and had higher size-corrected mass than their female nest mates (the same was evident in adult breeders). In 2002 (the year with the longer effective breeding season), body mass and condition declined with progressing hatching date and this effect was significantly more pronounced in male than in female nestlings. There was also a seasonal decline in male wing length, while female wing length remained relatively constant, which resulted in males having shorter wings than females in late broods. Tarsus length was unaffected by time of breeding, except that the difference between males and females was relatively smaller in late (i.e. second) broods in 2002. While these results are in accordance with the idea of an increased environmental sensitivity of the larger males, confounding effects of sex-differential hatching order cannot be ruled out. Dedicated to Doris Winkel.