Many birds species breed in colonies.One of the species in the Corvidae family nesting in groups is the Rook(Corvus frugilegus).The construction of the nest is costly for birds and needs high energy expenditure.Theref...Many birds species breed in colonies.One of the species in the Corvidae family nesting in groups is the Rook(Corvus frugilegus).The construction of the nest is costly for birds and needs high energy expenditure.Therefore,birds should optimize the time of nest building in relation to environmental,especially weather,conditions.Furthermore,birds should adapt their breeding phenology,including the date of starting the construction of nests for climate change.We observed the dynamics of increasing numbers of nests in a colony of Rooks in relation to air temperature,wind,rainfall,snowfall and day-length(indirect indicator of photoperiodism).Observations were carried out during three breeding seasons(2015-2017)in a large rookery in a big city in north-eastern Poland.The increase in the number of nests was correlated only with day length and no effect of climatic factors on the number of nests in the colony was observed.Number of nests varied significantly between successive years of research.In the case of the Rook(predictable breeders),the photoperiod seems to be the most important factor influencing breeding behavior,especially nest construction.In the last three decades,increasing temperature and time of spring phases have advanced and have influenced changes in the phenology of the availability of food resources.Simultaneously,a rapid decline in the numbers of breeding pairs of the Rook in Poland has been observed,especially in the last three decades.Conservative attachment to the length of the day,which is the main factor responsible for the development of the breeding colony,makes the Rook appear to be a species with low plasticity in the face of rapid climate changes.Thus,we suggest that may indirectly influence the decrease in the breeding population of the Rook.展开更多
RIASSUNTO-In due aree della città di Brescia si è accertata la presenza non occasionale di Cornacchiegrigie.Queste aree sono localizzate a nord ed a ovest(dove è stata rilevata la presenza di un nido)de...RIASSUNTO-In due aree della città di Brescia si è accertata la presenza non occasionale di Cornacchiegrigie.Queste aree sono localizzate a nord ed a ovest(dove è stata rilevata la presenza di un nido)del centro storico della città.La presenza delle Cornacchie è simile nelle due aree di studio e varia infunzione della stagione e della presenza umana.L’Autore discute il vantaggio adattativo di tale colonizza-zione,anche se il limite imposto dall’esiguo numero di soggetti per ora presenti impone cautela nell’inter-pretazione dei dati.First data on the presence of Hooded Crows Corvus corone cornix in Brescia(NorthernItaly).Two areas near the centre of the town of Brescia were kept under observation in the courseof the day and of the year to ascertain the non occasional presence of hooded crows.These areas arelocalized north and west from the centre of the town.The number of Hooded Crows is similar in bothareas but,throughout the year,it fluctuates with seasons and human presence.A nest presence hasbeen ascertained in the western area were the animals are more regularly present throughout the year.I argue the adaptive advantage of this colonization.展开更多
RIASSUNTO-Nel corso di tre inverni(1990-91,1991-92 e 1992-93)sono stati osservati,lungo differentipercorsi stradali della Valpadana centrale,10370 Corvi.Per ogni individuo sono stati rilevati tipo dicoltivazione sulla...RIASSUNTO-Nel corso di tre inverni(1990-91,1991-92 e 1992-93)sono stati osservati,lungo differentipercorsi stradali della Valpadana centrale,10370 Corvi.Per ogni individuo sono stati rilevati tipo dicoltivazione sulla quale era posato,ampiezza del campo e presenza di filari/siepi.In anni singoli sonostati esaminati altri fattori(distanza da abitazioni,dalla strada e dai filari o loro uso come posatoio).Lungo un percorso di circa 70 km(Cremona-Pavia)è stata inoltre rilevata la posizione cartografica deiCorvi osservati.Dai dati raccolti si può dedurre che questa specie può svernare soltanto in aree consufficiente varietà colturale e paesaggio agrario tradizionale,e che modificazioni gestionali possono elimi-narne la presenza.Wintering Rooks,Corvus frugilegus L.,in the central Po Valley and conservation ofthe traditional agricultural landscape.During three winter seasons(1990-91,1991-92 and 1992-93)10370Rooks were observed,along roads of the central Po Valley.The kind of cultivation,the extension offield and the presence of tree rows/hedges was noted for every resting Rook.Other factors(distancefrom habitations,road and tree rows,and their use for resting)were examined during single years.Alonga 70 km road(Cremona-Pavia,Northern Italy)the geographic position of the observed Rooks was noted.According to the observations,it seems that Rooks can winter only in areas with sufficiently variouscultivations and a traditional agricultural landscape,and that variations in their management can elimina-te the presence of the species.展开更多
Reaction of wild Hooded Crows to conspecific mummified in particolar postures and exposedin the field.A method for preparing bird specimens to be used as stimulus-objects in the field was tested bymeasuring the respon...Reaction of wild Hooded Crows to conspecific mummified in particolar postures and exposedin the field.A method for preparing bird specimens to be used as stimulus-objects in the field was tested bymeasuring the response of wild Hooded Crows,Corvus corone cornix.In a first series of experiments,HoodedCrows specimens were tested for general responsiveness and posture discrimination by conspecific.Moreapproaches were consistently made to Bristle-head posture than to Sleeked posture.In a combination of bristle-head specimens of different subspecies and species,C.c.corone was approached more times than C.c.cornix,whereas C.frugilegus elicited intermediate interest.In a different combination of bristle-head specimens,C.c.corone was more attractive than C.c.cornix,whereas a hybrid C.c.corone x cornix was less attractive than eachpure form.The approaches were usually aggressive.Bristle-head posture was confirmed to be a self advertisingposture and the comparisons between subspecies provided suggestions about the mechanism againsthybridation.展开更多
In many songbirds, the space use of breeders is well studied but poorly understood for non-breeders. In common ravens, some studies of non-breeders indicate high vagrancy with large individual differences in home rang...In many songbirds, the space use of breeders is well studied but poorly understood for non-breeders. In common ravens, some studies of non-breeders indicate high vagrancy with large individual differences in home range size, whereas others show that up to 40% of marked non-breeders can be regularly observed at the same anthropogenic food source over months to years. The aim of this study was to provide new insights on ravens＇ behavior during dispersal in the Eastern Alps. We deployed Global Positioning System （GPS） loggers on 10 individuals to gather accurate spatial and temporal information on their movements to quantify： 1） the dimension of the birds＇ space use （home range size with seasonal effects and daily/long-term travel distances）, 2） how long they stayed in a dispersal stage of wandering as opposed to settling temporarily, and 3） their destination of movements. We recorded movements of up to 40km per hour, more than 160km within 1 day and more than 11,000 km within 20 months, indicating high vagrancy. Switching frequently between temporarily settling and travelling large distances in short time intervals leads to extensive home ranges, which also explains and com- bines the different findings in the literature. The destinations are rich anthropogenic food sources, where the birds spent on average 75% of their time. We discuss how ravens may find these ＂feeding hot spots＂ and which factors may influence their decision to stay/leave a site. The strong dependence on anthropogenic resources found in this population may have implications for site management and conservation issues.展开更多
文摘Many birds species breed in colonies.One of the species in the Corvidae family nesting in groups is the Rook(Corvus frugilegus).The construction of the nest is costly for birds and needs high energy expenditure.Therefore,birds should optimize the time of nest building in relation to environmental,especially weather,conditions.Furthermore,birds should adapt their breeding phenology,including the date of starting the construction of nests for climate change.We observed the dynamics of increasing numbers of nests in a colony of Rooks in relation to air temperature,wind,rainfall,snowfall and day-length(indirect indicator of photoperiodism).Observations were carried out during three breeding seasons(2015-2017)in a large rookery in a big city in north-eastern Poland.The increase in the number of nests was correlated only with day length and no effect of climatic factors on the number of nests in the colony was observed.Number of nests varied significantly between successive years of research.In the case of the Rook(predictable breeders),the photoperiod seems to be the most important factor influencing breeding behavior,especially nest construction.In the last three decades,increasing temperature and time of spring phases have advanced and have influenced changes in the phenology of the availability of food resources.Simultaneously,a rapid decline in the numbers of breeding pairs of the Rook in Poland has been observed,especially in the last three decades.Conservative attachment to the length of the day,which is the main factor responsible for the development of the breeding colony,makes the Rook appear to be a species with low plasticity in the face of rapid climate changes.Thus,we suggest that may indirectly influence the decrease in the breeding population of the Rook.
文摘RIASSUNTO-In due aree della città di Brescia si è accertata la presenza non occasionale di Cornacchiegrigie.Queste aree sono localizzate a nord ed a ovest(dove è stata rilevata la presenza di un nido)del centro storico della città.La presenza delle Cornacchie è simile nelle due aree di studio e varia infunzione della stagione e della presenza umana.L’Autore discute il vantaggio adattativo di tale colonizza-zione,anche se il limite imposto dall’esiguo numero di soggetti per ora presenti impone cautela nell’inter-pretazione dei dati.First data on the presence of Hooded Crows Corvus corone cornix in Brescia(NorthernItaly).Two areas near the centre of the town of Brescia were kept under observation in the courseof the day and of the year to ascertain the non occasional presence of hooded crows.These areas arelocalized north and west from the centre of the town.The number of Hooded Crows is similar in bothareas but,throughout the year,it fluctuates with seasons and human presence.A nest presence hasbeen ascertained in the western area were the animals are more regularly present throughout the year.I argue the adaptive advantage of this colonization.
文摘RIASSUNTO-Nel corso di tre inverni(1990-91,1991-92 e 1992-93)sono stati osservati,lungo differentipercorsi stradali della Valpadana centrale,10370 Corvi.Per ogni individuo sono stati rilevati tipo dicoltivazione sulla quale era posato,ampiezza del campo e presenza di filari/siepi.In anni singoli sonostati esaminati altri fattori(distanza da abitazioni,dalla strada e dai filari o loro uso come posatoio).Lungo un percorso di circa 70 km(Cremona-Pavia)è stata inoltre rilevata la posizione cartografica deiCorvi osservati.Dai dati raccolti si può dedurre che questa specie può svernare soltanto in aree consufficiente varietà colturale e paesaggio agrario tradizionale,e che modificazioni gestionali possono elimi-narne la presenza.Wintering Rooks,Corvus frugilegus L.,in the central Po Valley and conservation ofthe traditional agricultural landscape.During three winter seasons(1990-91,1991-92 and 1992-93)10370Rooks were observed,along roads of the central Po Valley.The kind of cultivation,the extension offield and the presence of tree rows/hedges was noted for every resting Rook.Other factors(distancefrom habitations,road and tree rows,and their use for resting)were examined during single years.Alonga 70 km road(Cremona-Pavia,Northern Italy)the geographic position of the observed Rooks was noted.According to the observations,it seems that Rooks can winter only in areas with sufficiently variouscultivations and a traditional agricultural landscape,and that variations in their management can elimina-te the presence of the species.
文摘Reaction of wild Hooded Crows to conspecific mummified in particolar postures and exposedin the field.A method for preparing bird specimens to be used as stimulus-objects in the field was tested bymeasuring the response of wild Hooded Crows,Corvus corone cornix.In a first series of experiments,HoodedCrows specimens were tested for general responsiveness and posture discrimination by conspecific.Moreapproaches were consistently made to Bristle-head posture than to Sleeked posture.In a combination of bristle-head specimens of different subspecies and species,C.c.corone was approached more times than C.c.cornix,whereas C.frugilegus elicited intermediate interest.In a different combination of bristle-head specimens,C.c.corone was more attractive than C.c.cornix,whereas a hybrid C.c.corone x cornix was less attractive than eachpure form.The approaches were usually aggressive.Bristle-head posture was confirmed to be a self advertisingposture and the comparisons between subspecies provided suggestions about the mechanism againsthybridation.
文摘In many songbirds, the space use of breeders is well studied but poorly understood for non-breeders. In common ravens, some studies of non-breeders indicate high vagrancy with large individual differences in home range size, whereas others show that up to 40% of marked non-breeders can be regularly observed at the same anthropogenic food source over months to years. The aim of this study was to provide new insights on ravens＇ behavior during dispersal in the Eastern Alps. We deployed Global Positioning System （GPS） loggers on 10 individuals to gather accurate spatial and temporal information on their movements to quantify： 1） the dimension of the birds＇ space use （home range size with seasonal effects and daily/long-term travel distances）, 2） how long they stayed in a dispersal stage of wandering as opposed to settling temporarily, and 3） their destination of movements. We recorded movements of up to 40km per hour, more than 160km within 1 day and more than 11,000 km within 20 months, indicating high vagrancy. Switching frequently between temporarily settling and travelling large distances in short time intervals leads to extensive home ranges, which also explains and com- bines the different findings in the literature. The destinations are rich anthropogenic food sources, where the birds spent on average 75% of their time. We discuss how ravens may find these ＂feeding hot spots＂ and which factors may influence their decision to stay/leave a site. The strong dependence on anthropogenic resources found in this population may have implications for site management and conservation issues.
