Lindude põgenemiskäitumine erineva kisklusriskiga olukordades: terviklikum käsitlus

Väitekirja elektrooniline versioon ei sisalda publikatsiooneSuurema hirmutunde korral panustavad loomad enam aega valvsusele ja ohtu silmates põgenevad varem. Inimene võib oma tegevustega tahtmatult loomade hirmutunnet suurendada, põhjustades halbu käitumisotsuseid ja populatsiooni arvukuse langust. Loomade hirmutunde hindamiseks mõõdetakse enamasti kas nende valvsust või põgenemiskaugust. Doktoritöös uuriti, kas üheainsa käitumispõhise indikaatori mõõtmisest siiski piisab, et lindude hirmutunnet ja põgenemisega seotud kulutusi veenvalt hinnata. Lisaks selgitati, kas linnud jätkavad kiskja jälgimist veel ka põgenemise ajal ja milliseid lisategureid tuleks põgenemiskäitumise uurimisel arvesse võtta. Doktoritöö raames uuriti standardiseeritud viisil kümnete linnuliikide põgenemiskäitumist mitmel pool üle Euroopa, et tuvastada üldisi trende lindude käitumismustrites. Põgenemiskäitumise poolest olid linnalinnud mitmes mõttes julgemad kui maalinnud ning laiuskraadi kasvades muutusid linnud vähem ettevaatlikuks. Üllatuslikult olid linnalinnud valvsamad kui maalinnud ning vastupidiselt varem eeldatule viivitasid valvsamad linnud mõlemas elupaigas põgenemisega kauem. Need tulemused seavad valvsuse tavapärase kasutatavuse lindude hirmutunde kirjeldamiseks kahtluse alla. Tööst ilmnes veel, et lisaks enamasti uuritavale põgenemiskaugusele tuleks mõõta ka põgenemishetkele järgnevaid käitumismustreid. Need täiendavad mõõtmised annavad terviklikuma ülevaate põgenemisega seotud ajalistest ja energeetilistest kulutustest, mis omakorda aitab kaasa põgenemisotsuste mõistmisele. Näiteks leiti, et põgenemisele kulutatud aeg sõltub hirmutunde dünaamikast põgenemise ajal. See on esimene eksperimentaalne tõend, et linnud jätkavad kiskja jälgimist ka pärast põgenemise alustamist. Doktoritöö tulemused toetasid ka varasemaid uuringuid, mis on leidnud, et põgenemisotsuseid mõjutavad ka näiteks liigiomane kehamass, peidupaiga lähedus ja seltsingu suurus. Doktoritööst saadud teadmised aitavad paremini ennustada, kuidas lindude hirmutunne võib inimtekkeliste häiringutega seoses muutuda, mis omakorda aitab kaasa looduskaitseliste meetmete planeerimisele.Animals with higher levels of fearfulness will spend more time being vigilant and will escape earlier after having spotted a potential threat. Human-caused disturbances can involuntarily increase fearfulness in animals, which can result in inaccurate behavioural decisions that can lead to population declines. The most common measures of fearfulness in animals are vigilance and flight initiation distance. Present thesis examined whether the use of a single behavioural indicator is enough to assess fearfulness and costs related to escape. The thesis also investigated whether birds continue to monitor predators during escape, and which other factors should be considered when studying escape behaviour. Tens of bird species were studied across Europe in a standardized way to find general patterns in the behaviour of birds. Urban birds were characterized by a more relaxed escape behaviour than rural birds. In addition, birds took longer to become alert to threats as latitude increased. Surprisingly, urban birds were more vigilant than rural birds, and, contrary to the prevalent theory, vigilant birds delayed escape more. These results raise doubt whether vigilance should be used as an indicator of fearfulness in birds. The thesis also highlighted that in addition to measuring flight initiation distance, it is important to measure subsequent behavioural decisions. Doing so provides a more complete view of the energetic and opportunity costs of escape, which helps to understand escape-related decisions. For example, it was found that escape duration depends on how the perceived risk of predation changes while fleeing. That is the first experimental evidence that birds continue to monitor predators after initiating escape. Last, the evidence from the thesis complements previous research that, for example, has found body mass, distance to refuge, and group size to influence escape decisions in animals. The knowledge gained from the thesis improves predictions about the impact of human-caused disturbances on fearfulness in birds, which in turn benefits decision making in wildlife management.https://www.ester.ee/record=b529839

What are the important landscape components for habitat selection of the ortolan bunting Emberiza hortulana in northern limit of range?

Ortolan buntings Emberiza hotulana have undergone one of the most severe population declines of any European farmland bird over the last thirty years. The aim of this study was to find out which habitat features, including crop characteristics, ortolan bunting prefers in Estonia in breeding areas. This study compared currently occupied and unoccupied ortolan bunting territories. Occupied areas contained significantly more tall broadleaf trees, crop types, structural elements (trees, bushes, roads, overhead power lines and buildings) and spring wheat, but also had lower crop drilling densities. Ortolan bunting territories were best described by a logistic regression model containing six variables: amount of structural point elements, length of power lines, amount of tall broadleaf trees and number of different crops had a positive effect, whereas crop density and area of autumn-sown crops had a negative effect. Based on the findings of this study, the following conservation measures can be recommended: lower crop densities; spring rather than autumn-sown crops; small-field systems containing a variety of crops; scattered scrub preserved or planted; habitat patches of permanent grasslands, hedges and tall broadleaf trees retained within the agricultural landscape

What are the important landscape components for habitat selection of the ortolan bunting Emberiza hortulana in northern limit of range?

Ortolan buntings Emberiza hotulana have undergone one of the most severe population declines of any European farmland bird over the last thirty years. The aim of this study was to find out which habitat features, including crop characteristics, ortolan bunting prefers in Estonia in breeding areas. This study compared currently occupied and unoccupied ortolan bunting territories. Occupied areas contained significantly more tall broadleaf trees, crop types, structural elements (trees, bushes, roads, overhead power lines and buildings) and spring wheat, but also had lower crop drilling densities. Ortolan bunting territories were best described by a logistic regression model containing six variables: amount of structural point elements, length of power lines, amount of tall broadleaf trees and number of different crops had a positive effect, whereas crop density and area of autumn-sown crops had a negative effect. Based on the findings of this study, the following conservation measures can be recommended: lower crop densities; spring rather than autumn-sown crops; small-field systems containing a variety of crops; scattered scrub preserved or planted; habitat patches of permanent grasslands, hedges and tall broadleaf trees retained within the agricultural landscape

Rural-Urban Differences in Escape Behavior of European Birds across a Latitudinal Gradient

Behavioral adjustment is a key factor that facilitates species’ coexistence with humans in a rapidly urbanizing world. Because urban animals often experience reduced predation risk compared to their rural counterparts, and because escape behavior is energetically costly, we expect that urban environments will select for increased tolerance to humans. Many studies have supported this expectation by demonstrating that urban birds have reduced flight initiation distance (FID = predator-prey distance when escape by the prey begins) than rural birds. Here, we advanced this approach and, for the first time, assessed how 32 species of birds, found in 92 paired urban-rural populations, along a 3,900 km latitudinal gradient across Europe, changed their predation risk assessment and escape strategy as a function of living in urban areas. We found that urban birds took longer than rural birds to be alerted to human approaches, and urban birds tolerated closer human approach than rural birds. While both rural and urban populations took longer to become aware of an approaching human as latitude increased, this behavioral change with latitude is more intense in urban birds (for a given unit of latitude, urban birds increased their pre-detection distance more than rural birds). We also found that as mean alert distance was shorter, urban birds escaped more quickly from approaching humans, but there was no such a relationship in rural populations. Although, both rural and urban populations tended to escape more quickly as latitude increased, urban birds delayed their escape more at low latitudes when compared with rural birds. These results suggest that urban birds in Europe live under lower predation risk than their rural counterparts. Furthermore, the patterns found in our study indicate that birds prioritize the reduction of on-going monitoring costs when predation risk is low. We conclude that splitting escape variables into constituent components may provide additional and complementary information on the underlying causes of escape. This new approach is essential for understanding, predicting, and managing wildlife in a rapidly urbanizing world.Peer reviewe

dataset.fid.gregarious.2019

Dataset associated to the article "Contagious fear: Escape behaviour increases with flock size in European gregarious birds" by Morelli et al. 2019. Metadata: Variable Details Species Species latin name FID_mean Flight initiation distance measured in meters (mean value) n No. observations of FID initiation Starting distance species Scientific name diet.specific Type of diet gregariousness gregarious bdm.quant body mass quartile latitude Latitude in decimel degrees habitat Type of habitat: Rural or urban flock Flock size (individuals) bodymass body mass (g

Data from: Contagious fear: escape behaviour increases with flock size in European gregarious birds

Flight initiation distance (FID), the distance at which individuals take flight when approached by a potential (human) predator, is a tool for understanding predator-prey interactions. Among the factors affecting FID, tests of effects of group size (i.e. number of potential prey) on FID have yielded contrasting results. Group size or flock size could either affect FID negatively (i.e. the dilution effect caused by the presence of many individuals) or positively (i.e. increased vigilance due to more eyes scanning for predators). These effects may be associated with gregarious species, because such species should be better adapted to exploiting information from other individuals in the group than non-gregarious species. Sociality may explain why earlier findings on group size vs. FID have yielded different conclusions. Here, we analyzed how flock size affected bird FID in eight European countries. A phylogenetic generalized least square regression model was used to investigate changes in escape behavior of bird species in relation to number of individuals in the flock, starting distance, diet, latitude and type of habitat. Flock size of different bird species influenced how species responded to perceived threats. We found that gregarious birds reacted to a potential predator earlier (longer flight initiation distance) when aggregated in large flocks. These results support a higher vigilance arising from many eyes scanning in birds, suggesting that sociality may be a key factor in the evolution of anti-predator behavior both in urban and rural areas. Finally, future studies comparing FID must pay explicit attention to the number of individuals in flocks of gregarious species

Contagious fear: Escape behavior increases with flock size in European gregarious birds

Abstract Flight initiation distance (FID), the distance at which individuals take flight when approached by a potential (human) predator, is a tool for understanding predator–prey interactions. Among the factors affecting FID, tests of effects of group size (i.e., number of potential prey) on FID have yielded contrasting results. Group size or flock size could either affect FID negatively (i.e., the dilution effect caused by the presence of many individuals) or positively (i.e., increased vigilance due to more eyes scanning for predators). These effects may be associated with gregarious species, because such species should be better adapted to exploiting information from other individuals in the group than nongregarious species. Sociality may explain why earlier findings on group size versus FID have yielded different conclusions. Here, we analyzed how flock size affected bird FID in eight European countries. A phylogenetic generalized least square regression model was used to investigate changes in escape behavior of bird species in relation to number of individuals in the flock, starting distance, diet, latitude, and type of habitat. Flock size of different bird species influenced how species responded to perceived threats. We found that gregarious birds reacted to a potential predator earlier (longer FID) when aggregated in large flocks. These results support a higher vigilance arising from many eyes scanning in birds, suggesting that sociality may be a key factor in the evolution of antipredator behavior both in urban and rural areas. Finally, future studies comparing FID must pay explicit attention to the number of individuals in flocks of gregarious species

Data from: Contagious fear: escape behaviour increases with flock size in European gregarious birds

Flight initiation distance (FID), the distance at which individuals take flight when approached by a potential (human) predator, is a tool for understanding predator-prey interactions. Among the factors affecting FID, tests of effects of group size (i.e. number of potential prey) on FID have yielded contrasting results. Group size or flock size could either affect FID negatively (i.e. the dilution effect caused by the presence of many individuals) or positively (i.e. increased vigilance due to more eyes scanning for predators). These effects may be associated with gregarious species, because such species should be better adapted to exploiting information from other individuals in the group than non-gregarious species. Sociality may explain why earlier findings on group size vs. FID have yielded different conclusions. Here, we analyzed how flock size affected bird FID in eight European countries. A phylogenetic generalized least square regression model was used to investigate changes in escape behavior of bird species in relation to number of individuals in the flock, starting distance, diet, latitude and type of habitat. Flock size of different bird species influenced how species responded to perceived threats. We found that gregarious birds reacted to a potential predator earlier (longer flight initiation distance) when aggregated in large flocks. These results support a higher vigilance arising from many eyes scanning in birds, suggesting that sociality may be a key factor in the evolution of anti-predator behavior both in urban and rural areas. Finally, future studies comparing FID must pay explicit attention to the number of individuals in flocks of gregarious species.,dataset.fid.gregarious.2019Dataset associated to the article "Contagious fear: Escape behaviour increases with flock size in European gregarious birds" by Morelli et al. 2019. Metadata: Variable Details Species Species latin name FID_mean Flight initiation distance measured in meters (mean value) n No. observations of FID initiation Starting distance species Scientific name diet.specific Type of diet gregariousness gregarious bdm.quant body mass quartile latitude Latitude in decimel degrees habitat Type of habitat: Rural or urban flock Flock size (individuals) bodymass body mass (g)