| Reproduction is the most important stage in avian life history,which is related to breeding success and population growth.And reproductive ecology of tropical birds has been less studied than that of temperate birds.By using field observation combined with mini-camera video monitoring,reproductive behavior of the Oriental Magpie Robin(Copsychus saularis)in the tropical Hainan island with one urban population(Haikou city)and two rural populations(Ding'an and Lingshui),were investigated.In addition,incubation and nestling feeding behaviors recorded by sampling and recorded in the whole process of video monitoring were compared.The main results and conclusion of this study were as followings:1.The breeding period of the Oriental Magpie Robin is from March to August,with two peaks of the first egg-laying.The nest is shallow cup or dish shape,and nest materials inside include grass roots,grass stems,black silk and other soft materials,while outside are mainly moss,branches,leaves,coconut bark,and so on.There were no significant differences in nest materials,like artificial plastics and hair,between urban and rural areas.There were also no differences between urban and rural areas with nesting period(Haikou:6.40 ± 0.89 d,n=5;Lingshui:7.12 ± 3.57 d,n=17;Ding'an:5.86±1.07d,n=7)and nest size(nest depth,Haikou:6.31±1.00 cm,n=7;Lingshui:6.37 ± 1.21 cm,n=47;nest diameter,Haikou:10.33 ± 0.89 cm,n=7;Lingshui:9.72±1.30 cm,n=47).However,more nest materials were found in urban area(Haikou:9.39±0.53 cm in depth,n=7)than those in rural area(Lingshui:8.14 ±1.76 cm,n=25).2.Oriental Magpie Robins lay eggs continuously with one egg per day.Eggs are oval and blue green with brown spots in color.There were no differences between urban and rural areas for the first egg-laying time(Haikou:7:58:27±1:27:12 a.m.,n=8;Lingshui:7:47:49±1:28:01 a.m.,n=24;Ding'an:7:35:48±0:59:30 a.m.,n=7),time of laying an egg(Haikou:21.93±5.62 min,n=8;Lingshui:24.73±13.03 min,n=24;Ding'an:26.32±7.72 min,n=7),clutch size(Haikou:4.55 ± 0.52,n=11;Lingshui:4.65±0.57,n=68;Ding'an:4.17±0.83,n=30),egg mass(Haikou:3.21 ±0.51 g,n=10;Lingshui:3.22±0.28 g,n=68;Ding'an:3.04±0.26 g,n=20)and egg volume(Haikou:3.18±0.35 cm3,n=10;Lingshui:3.12±0.28 cm3,n=68;Ding'an:2.98 ± 0.24 cm3,n=20).However,clutch size and egg mass in Lingshui were significantly larger than those in Ding'an(both were in rural areas).3.In the Oriental Magpie Robin,only the female incubates.No significant difference for incubation period was found between urban(Haikou:11.60±0.55 d,n=5)and rural areas(Lingshui:12.03±0.80 d,n=34;Ding'an:11.50±0.53 d,n=10).There were also no significant differences for daily incubation time(Haikou:879.79 ±101.04 min,n=28;Lingshui:987.47±116.63 min,n=49;Ding'an:920.87±79.69 min,n=13),daily activity time(Haikou:560.21±101.04 min,n=28;Lingshui:452.53±116.63 min,n=49;Ding'an:519.13±79.69 min,n=13),daily recess times(Haikou:26.68±6.79 times,n=28;Lingshui:23.16±5.43 times,n=49;Ding'an:27.69±9.07 times,n=13),the earliest time of leaving the nest(Haikou:5:49:04±0:06:57 a.m.,n=28;Lingshui:6:05:11±0:10:32 a.m.,n=52;Ding'an:5:53:53±0:16:27 a.m.,n=13)and the latest time back the nest(Haikou:19:16:14±0:16:12 p.m.,n=29;Lingshui:18:50:35±0:27:43 p.m.,n=53;Ding'an:18:50:49±0:49:29 p.m.,n=12),and the number of egg turning per day(Haikou:44.14±13.85 times,n=28;Lingshui:65.53 ±16.99 times,n=49;Ding'an:56.31±16.07 times,n=13).4.At the nestling stage,both the female and male feed nestlings together.The body mass,wing and tarsus length of the nestlings increased with age.No significant differences for time period of nestling feeding and nestling growth were found between urban(Haikou:14.00±1.00 d,n=3)and rural areas(Lingshui:14.74±0.81 d,n=23;Ding'an:14.67±1.23 d,n=15).At 3 and 6 days of nestling age,there were no differences between urban and rural areas.However,at 9 and 12 days of nestling age,the feeding frequency of parents in Ding'an(rural area)was much higher than those of other two populations,which might be due to abundance of food in the orchard.In addition,there were no significant differences for nestling sex ratio between Lingshui and Ding'an populations,and the overall nestling sex ratio of the Oriental Magpie Robin was 1:1.01(female:male),which was in line with the prediction from sex distribution theory.5.For Oriental Magpie Robins,hatching success(Haikou:56.0%;Ding'an:62.3%)and reproductive success(Haikou:45.0%;Ding'an:55.3%)in Haikou and Ding'an populations were significantly lower than those in Lingshui(80.9%and 79.6%,respectively).However,no significant differences in reproductive capacity were found among three populations(Haikou:3.75±0.96 nestlings per pair,n=4;Lingshui:3.48±1.02 nestlings per pair,n=60;Ding'an:3.29±1.16 nestlings per pair,n=17).Two cases of nestling killing by non-parent males were found for the first time in the Oriental Magpie Robin.Biting and killing by ants(mostly from Crematogaster spp.)were the main causes of nestling death and breeding failure in the Oriental Magpie Robin.6.Incubation and nestling feeding behaviors recorded by sampling and recorded in the whole process of video monitoring were compared,and results showed that there were no significant differences between the two methods in day incubation time,recess time and number of egg-turning.Therefore,data of incubation and nestling feeding recorded by sampling at random time,i.e.,at 3,6,9 and 12 days,may provide useful information similar to those recorded in the whole process of video monitoring.7.Three feeding patterns(females directly to nestlings,males directly to nestlings and males first to females and then to nestlings)were observed in the Oriental Magpie Robin,with feeding frequency of females being significantly higher than that of males.There were no significant differences for parent feeding frequency,brood-warming behavior,number of brood-warming per day and nest sanitation,between data recorded by sampling and recorded in the whole process of video monitoring.The peak of parent feeding frequency was from 6:00 a.m.to 8:00 a.m.and increased with nestling age.Only the female took brood-warming behavior and the number of brood-warming decreased with nestling age,however,the duration of brood-warming did not change with nestling age.For nest sanitation,the frequency of feces carried by female birds was significantly higher than that of male birds.To sum up,for magpie robins in urban areas,their nests are bigger,day of the incubation time is shorter,activity in daytime is more,but egg turning is less than those of rural populations,suggesting heat island effect,noise and human interference could have negative impact on avian reproduction.There was no significant difference between part-video recording(sampling nests)and full-video recording(full monitoring nests)data for behaviours of incubation,nestling feeding and nest sanitation.Innovation:1.Effect of urbanization on reproduction of the Oriental Magpie Robin was investigated.2.Two cases of nestling killing by non-parent males were found and reported for the first time in the Oriental Magpie Robin.3.This study confirmed that data of incubation and nestling feeding recorded by sampling at random time may provide useful information similar to those recorded in the whole process of video monitoring. |
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