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PubMed2002

[On nest-site selection of Otic tarda].

During April to July in 2000 and 2001, the nest-site selection of Otis tarda was studied by direct observation and sampling method in the southeast grassland of Keyouqianqi in Inner Mongolia. The results showed that Otis tarda was one kind of big-sized bird built nests on the ground in sparse cluster, and the smallest distance between nests was 9 m. Otis tarda had a significant tendency in nest-site selection. Firstly, this tendency was represented under the scale of landscape. Most nests of Otis tarda were built on the mid-hill of grassland, the elevation range was from 190 m to 230 m, most nests built on the slopes faced to sun, and the biggest gradient was not more than 8 degree. Moreover, the nests were near to roads. Secondly, Otis tarda selected its nest-site according to vegetation structure. It tended to select nest-site with thick hay, high vegetation density and grass height from 15 cm to 35 cm, but would not select the place with over high vegetation density no nest.

Animals↗
PubMed2003

Breeding performance of great tits (Parus major) along a gradient of heavy metal pollution.

The possible effects of heavy metal pollution on various breeding parameters of the great tit (Parus major) were studied at four study sites in a pollution gradient near a large nonferrous smelter in Belgium during three consecutive breeding seasons. Significantly more females interrupted their laying period near the pollution source than did females farther away. At the two most polluted sites, hatching success was significantly reduced compared to two lesser-polluted study sites. Overall breeding success was also significantly lower toward the factory complex. This lowered breeding success was caused not only by the decreased hatching success toward the pollution source but also by the significant difference in fledging success among sites. Although a clear relationship was observed between the exposure to heavy metal pollution and an impaired reproduction, not all reproductive parameters were affected. We found no significant differences in the onset of laying, clutch size, length of the incubation period, and the proportion of nests with low-quality eggs among sites. Although nest box occupancy was every year slightly lower toward the smelter compared to farther away, differences among study sites were never significant.

Animals↗
PubMed2003

[Egretta garzetta as a bioindicator of environmental pollution in Tai Lake region].

There were four species of Ardeidae in Tai Lake. The dominant vegetations in the habitat were Pinus massoniana, Cinnamomum hupehanum, Quercus acutissema, Ulmus prmila and Myrica rubra, which were suitable for Egretta garzetta to make nests. The area of the habitat was about 7 hm2, where there were totally 4200 Egretta garzetta nests with the density of 0.38 nest per tree in average. Studies on Egretta garzetta breeding ecology showed that the incubating time was 19-21 days, the average egg weight was 23.9 +/- 4.0 g(n = 41), and the average egg size was 44.5 +/- 4.1 mm x 32.6 +/- 4.9 mm(n = 41). The mean clutch size and brood size were 5.02(2-8) and 3.86(2-7), respectively, and the hatching rate was 84.25%. The measurements of Egretta garzetta nestling tarsus did not show any asymmetry (P > 0.05). Egretta garzetta fed mainly on small fish and shrimps in Tai Lake. The analysis results of Tai Lake samples showed that the pollutants including HCH, HCB, cyclodience, DDTs (DDT, DDE and DDD), PCBs, Cr, Hg and Pb in Egretta garzetta eggs were detected except Cd, and these pollutants accumulated through prey chain from sediments and preys to nestlings. Comparing samples from Tai Lake and those from Poyang Lake as relatively unpolluted area, only the concentration of DDTs residues was higher than 2 micrograms.g-1 in both lakes, and the other residues from Tai Lake like organochlorine insecticides, PCBs and heavy metals were all lower than those from Poyang Lake, and did not affect the development and breeding success of Egretta garzetta at present.

Animals↗
PubMed1976

[On the biological characterization of the outbred strain of Chbb : NMRI (SPF) mice / 1st comm.: Characterization of breeding stock under constant conditions of nutrition (Part II) (author's transl)].

The second part continued the biological characteization of the outbred strain Chbb : NMRI (SPF) (formerly NMRI/Tübingen/Kisslegg/Biberach) mice. The results obtained from 7 generations (F9 to F 15-generations) refer to the following parameters: loss of breeding animals, conception rate, ability to build a nest, litter size at birth and weaning, loss of young animals, litter weight at birth and weaning, intervals between two births and efficienty quota.

Animals↗
PubMed2003

[Demography and nesting ecology of green iguana, Iguana iguana (Squamata: Iguanidae), in 2 exploited populations in Depresión Momposina, Colombia].

We studied the demography and nesting ecology of two populations of Iguana iguana that face heavy exploitation and habitat modification in the Momposina Depression, Colombia. Lineal transect data was analyzed using the Fourier model to provide estimates of social group densities, which was found to differ both within and among populations (1.05-6.0 groups/ha). Mean group size and overall iguana density estimates varied between populations as well (1.5-13.7 iguanas/ha). The density estimates were far lower than those reported from more protected areas in Panama and Venezuela. Iguana densities were consistently higher in sites located along rivers (2.5 iguanas/group) than in sites along the margin of marshes, probably due to vegetational differences (1.5 iguanas/group). There was no correlation between density estimates and estimates of relative abundance (number of iguanas seen/hour/person) due to differing detectabilities of iguana groups among sites. The adult sex ratio (1:2.5 males:females) agreed well with other reports in the literature based upon observation of adult social groups, and probably results from the polygynous mating system in this species rather than a real demographic skew. Nesting in this population occurs from the end of January through March and hatching occurs between April and May. We monitored 34 nests, which suffered little vertebrate predation, perhaps due to the lack of a complete vertebrate fauna in this densely inhabited area, but nests suffered from inundation, cattle trampling, and infestation by phorid fly larvae. Clutch sizes in these populations were lower than all other published reports except for the iguana population on the highly xeric island of Curaçao, implying that adult females in our area are unusually small. We argue that this is more likely the result of the exploitation of these populations rather than an adaptive response to environmentally extreme conditions.

Animals↗
PubMed2004

[Migration dynamics of Grus japonensis in recent years spring and conservation of its habitat in Xianghai Nature Reserve].

A survey on the migratory Grus japonensis in Xianghai wetland was conducted in spring of 1997-2003, and the relationship between migratory dynamics of Grus japonensis and changes of wetland eco-environment was analyzed. The population of Grus japonensis in Xianghai was 32, 25, 64, 92, 72,59 and 14, respectively in the spring of 1997-2003. The smallest number was found in 2003, only 1 breeding pair, and the largest number was found in 2002, including 16 breeding pairs. The earliest year for Grus japonensis arrival was 2002 (March 12), and the latest year was 2001 (March 28). The earliest year for Grus japonensis laying eggs was 1998 (April 1), and the latest year was 2003 (May 10). Most cranes finished laying eggs in early April. The earliest day was 40 days earlier than the latest one. Among the seven years, the year when the distribution range of Grus japonensis was the widest was 2000, and the cranes mainly distributed in 15 sites, such as Fulaowunpao, Jiandipao, and so on. On the contrary, they distributed only in 2 sites in 1998 and 1 site in 2003. The number and the distribution range of Grus japonensis in 2000 were far larger than those in 1997, 1998 and 2003. The migratory dynamics of Grus japonensis changed with the water condition of Xianghai wetland in different years. Based on the characteristics of water eco-environment of Xianghai wetland, a strategy for protecting Grus japonensis by wisely using the flood resource was suggested.

Animal Migration↗
PubMed2005

[A comparative study on asynchronous hatching and nestling growth of three heron species].

The study on the asynchronous hatching and nestling growth of three heron species (Ardeola bacchus, Egretta garzetta, Nycticorax nycticorax) in laboratory and field at the Changshan and Yuhang heron reserve in Zhejiang Province in 1996-1999 showed that the herons migrated to the reserve in the first and second ten days of April, and left in late September. The average hatching period was 23.0 days for Ardeola bacchus, 23.9 days for Egretta garzetta, and 25.3 days for Nycticorax nycticorax. Nycticorax nycticorax had the highest hatching rate (95.45%), followed by Egretta garzetta (86.98%) and Ardeola bacchus (76.23%). The hatch ability of Nycticorax nycticorax (3.50) was higher than those of Egretta garzetta (3.38) and Ardeola bacchus (3.21). The increase of nestling weight was negatively related to the adult body size, but positively related to the hatching order. All nestlings developed well at their early growth stage, and then, there existed a significant difference among the nestlings based on the hatching order. The growth curves of the first three nestlings were similar and obviously better than that of the fourth, which indicated that early-hatched nestlings could obtain enough food, while the last one might be short of food. The optimal hatching quantity of the three heron species was assumed to be three offsprings.

Animals↗
PubMed2006

Growth strategies of passerine birds are related to brood parasitism by the brown-headed cowbird (Molothrus ater).

Sibling competition was proposed as an important selective agent in the evolution of growth and development. Brood parasitism by the brown-headed cowbird (Molothrus ater) intensifies sibling competition in the nests of its hosts by increasing host chick mortality and exposing them to a genetically unrelated nestmate. Intranest sibling competition for resources supplied by parents is size dependent. Thus, it should select for high development rates and short nestling periods, which would alleviate negative impacts of brood parasitic chicks on host young. I tested these predictions on 134 North American passerines by comparative analyses. After controlling for covariates and phylogeny, I showed that high parasitism rate was associated with higher nestling growth rate, lower mass at fledging, and shorter nestling periods. These effects were most pronounced in species in which sibling competition is most intense (i.e., weighing over about 30 g). When species were categorized as nonhosts versus old hosts (parasitized for thousands of years) versus new hosts (parasitized the last 100-200 years), there was a clear effect of this parasitism category on growth strategies. Nestling growth rate was the most evolutionarily flexible trait, followed by mass at fledging and nestling period duration. Adjustments during incubation (incubation period length, egg volume) were less pronounced and generally disappeared after controlling for phylogeny. I show that sibling competition caused by brood parasites can have strong effects on the evolution of host growth strategies and that the evolution of developmental traits can take place very rapidly. Human alteration of habitats causing spread of brood parasites to new areas thus cascades into affecting the evolution of life-history traits in host species.

Animals↗
PubMed1973

Ethological studies on polycalic colonies of the ants Formica exsecta nyl.

The members of a polycalic colony of Formica exsecta freely walk over its various nests, while performing social functions. It seems that the external service in the species ceases to belong strictly to one nest and forms a supra-nest attachment. The probability of this relation is more credible in the light of the results of this research which disclosed a tendency to local migrations. For, both these ethological peculiarities require an inhibition of the attachment to the restricted habitat, which seems to be characteristic of the species of the genus Formica. It seems that we are dealing here with a process of colony integration, and that we witness the extention of the social unit from the nest into the whole colony.

Animals↗