July 11, 2005
The 22nd chick of Japanese crested ibis (toki in Japanese) hatched on June 9, 2005 completing the breeding (egg laying and hatching) season of 2005. For this year, 7 pairs laid 42 eggs, and 22 chicks were hatched and are growing. Current population of Japanese crested ibis became 80.
Test of non-artificial breeding ability under captivity was conducted. One of the pairs succeeded in non-artificial hatching and non-artificial breeding of one chick as same as last year. In addition, all of the 7 pairs including this one succeeded in the test combining artificial hatching and non-artificial breeding. This confirms high chick breeding ability even under the captivity.
| 1. | Breeding policy in 2005 |
Among the individuals capable of breeding in Sado Toki Conservation Center, one pair out of 5 from 2004 was dissolved and 3 pairs were newly formed for breeding. For all the 7 pairs, non-artificial breeding was experimented depending on condition, and hatching and chick breeding ability were confirmed. (Table)
| 2. | Result of breeding in 2005 |
| In 2005, the first egg was laid by the pair F on March 21. During 55 days of this breeding season 42 eggs were laid by 6 pairs and the last egg of this season was laid by Pair G on May 14. This year , an average number of egg laid per pair was 6.0, which meant a decrease compared to 2004 (6.8), because the extensive have been attempted for non-artificial breeding since 2004 and the pair H did not lay eggs. |
| Among the 42 eggs, 27 sperm eggs (64.3%), 13 infertile eggs and 2 eggs were not candled because of breakage. The ratio of sperm eggs went down compared to 2004 (73.5%). The causes of this decline could include bad weather in the early part of the breeding season. |
| Out of 27 sperm eggs, total of 22 chicks were hatched, 21 with artificial hatching and one with non-artificial hatching. Five eggs did not hatch because of growth halt (1 egg), and egg breakage during the period between the last stage of incubation and just before hatching (4 eggs). Hatching ratio declined to 81.5% due to high egg breakage compared to 2004 (88.0%). As a result, the total number of individuals became 80. |
| 3. | Non-artificial breeding (hatching and chick breeding by parent ibis) |
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Pairs subjected to experiment |
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Non-artificial hatching |
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All of the 7 pairs were target for natural hatching. Due to following reasons, only 4 pairs (B, E, F and G) tried non-artificial hatching: |
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(i) Pair A: |
This pair failed to non-artificial hatch in 2002 and 2004. They dropped eggs out of their nest this season showing their unstable condition. |
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(ii) Pair D: |
This pair continuously laid infertile eggs. |
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(iii) Pair H: |
This pair did not lay any eggs. (It is presumed that sexual maturity of male was still low.) |
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Non-artificial chick breeding |
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All of the 7 pairs were experimented. |
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Non-artificial hatching |
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Observation was made by taking eggs from their nests leaving only 1 or 2 sperm eggs from 2nd clutch for pair B and 1st clutch for the other 3 pairs. |
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Non-artificial chick breeding |
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For those pairs succeeding in non-artificial hatching, one more sibling chick hatched artificially was added to their nests. For pairs not succeeding in non-artificial hatching, infertile egg or pseudo-egg being incubated was replaced by 3- to 5-day old artificially hatched chick. |
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Non-artificial hatching |
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For pairs E, F and G, eggs were broken by parent bird just before hatching. For pair G, their condition was better than other pairs, they tried on the 2nd clutch and succeeded in non-artificial hatching.
For Pair B, they tried on the 2nd clutch but the egg was broken by accident during latter part of incubation.
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Non-artificial chick breeding |
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Pair G had one chick hatched non-artificially and one artificially hatched sibling chick was added to their nest when chick was 3-day old. Both chicks are growing up soundly.
For pairs A, B, D, E, and F, their pseudo-egg or infertile egg they incubated for 31- to 45-days were replaced by 3- to 5-day old chick. There were differences in their feeding status to chick but all chicks were growing up soundly. Four of chicks already left their nests.
For pair H, pseudo-egg was placed to their nest since incubation activities were observed although the pair did not lay any eggs. They kept incubating and pseudo-egg was replaced by 4-day old artificially hatched chick from pair F. The sound chick breeding is on the way.
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Non-artificial hatching |
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Pairs B and E which succeeded in hatching in 2004 were not successful this year, but newly formed pair G succeeded in the 2nd clutch. |
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Non-artificial chick breeding |
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All of the 7 pairs succeeded. |
| As a result of experiment for non-artificial breeding this year, it was confirmed that Japanese crested ibis maintains high ability for chick breeding under the captivity. For the future plan, requirements for hatching including raising environment, structure of cages will be studied and confirming experiment will be conducted. |
| Video and still photograph are available for pair G which succeeded in non-artificial chick breeding, and their chick from the Wildlife Division, Nature Conservation Bureau, Ministry of the Environment (tel. +81-(0)3-5521-8283). |
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