Breeding Ecology And Anti-brood Parasitism Strategy Of The Common Myna In Pakistan

Research into the breeding ecology of birds is crucial in understanding their evolutionary,ecological,and behavioral characteristics but also for designing efficient conservation strategies.Urban environments can be appealing to certain species because they have more food sources and nesting opportunities,which can boost breeding or productivity.To determine how urbanization could affect various species of birds,it is crucial to comprehend how urbanization impacts the strategies they employ in their life histories.Brood parasitism or the egg placement inside others’nests is a method of reproduction that allows parasites to pass the burden of raising their offspring onto host birds.Avian brood parasitism can be reproductively expensive for hosts and opts for cognitive traits that enable the host to resist parasites in various stages of the breeding cycle.The most well-known defense is the rejection of eggs,and some hosts have developed sophisticated abilities to recognize and remove eggs that differ in appearance from their own,however,it appears that only a small number of hosts may reject to feed nestlings of parasitic cuckoos.The Common myna(Acridotheres tristis)(family,Sturnidae;order,Passeriformes)has the distinction of being the most widely distributed and the most frequently seen bird in the Indian subcontinent.It is found near human settlements in both rural and urban areas.Altogether,this thesis combines a great deal of information that explains and clarifies the breeding ecology and anti-brood parasitism strategy of the Common Myna(Acridotheres tristis)during the breeding seasons 2020-2021 in Pakistan.The results and conclusions were as follows:(1)The breeding ecology of Common Mynas in nest boxes was compared in urban and rural Mardan,Pakistan.Nests of the Common Myna are either oblong,round or desk shaped and both sexes participate in nest building.On average,for urban and rural populations respectively,the nest measurements were that,nest mass,64.87±38.84 and 48.53±30.81 g(P<0.05);nest outer diameter,14.54±3.87 and 17.12±2.28 cm(P<0.05);nest inner diameter,13.19±3.43 and12.89±2.73 cm(P<0.05);cup depth,13.62±8.1 and 12.84±6.3 cm(P>0.05).(2)The eggs of the Common Myna are oval blue or pale blue in color.For urban and rural areas respectively,the average egg measurements were as follows:egg mass,7.23±0.78 and7.49±0.80 g(P<0.05);egg length,27.61±1.33 and 27.68±1.06 mm(P>0.05);egg width,17.33±0.90 and 17.76±0.73 mm(P<0.05);egg volume,4.25±0.57 and 4.46±0.45 cm~3(P<0.05).The average breeding parameters in urban and rural areas were as follows:clutch size,4.95±0.6and 5.23±0.8(P>0.05);incubation period,15.93±0.9 and 16.28±0.9 days(P>0.05);brood size,4.35±0.93 and 4.67±0.8 nestlings(P>0.05);nestling period,21.4±1.24 and 24.5±1.94 days(P<0.05);hatching success,71.6 and 64.3%(P<0.05);fledging success,86.7 and 60.7%(P<0.05);breeding success,62.13 and 39.4%(P<0.05),respectively.Urban nestlings open their eyes earlier than rural nestlings after hatching(P<0.05).(3)In Pakistan,the common myna is a host of the non-evicting brood parasite,the Asian koel(Eudynamys scolopaceus).Therefore,both the urban and rural Common Myna populations were experimentally tested for egg recognition and nestling discrimination by introducing quail eggs,red-painted quail eggs,eggs of small passerines,dummy pigeon eggs,and cross-fostered chicks of various species with different nestling ages.The urban and rural Common Myna populations were able to accept large size foreign eggs while rejecting some small size non-mimetic eggs.Similarly,Common Mynas could eject foreign chicks if they were smaller than the host brood.Alternatively,Common Myna stopped feeding the nestling that hatched before the host brood.Our findings suggest that urban Common Mynas outperform rural myna population in terms of breeding success.Predation,nest orientation,habitat,and food availability all have an impact on breeding success of the Common Myna in Pakistan.The study emphasizes that the common myna’s discrimination mechanism is based on size and incubation time rather than color or begging sounds.Innovation:(1)The breeding ecology of Common Mynas in in urban and rural Mardan,Pakistan,was compared for the first time,and our study showed that urban Common Mynas outperform rural myna population in terms of breeding success.(2)To the best of our knowledge,this study provided the first experimental evidences that the Common Myna,a host of the Asian Koel,is able to reject parasitic eggs and nestlings based on the size of eggs and nestlings.