Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 42

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  Phasianus colchicus
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Detailed knowledge of demographic parameters (such as age structure and reproduction rates) is crucial for guiding conservation and management decisions regarding wildlife populations. Such parameters of wild ring-necked pheasant populations in the current agricultural landscape remain very poorly described. We researched age structure and reproduction rates of predominantly wild populations of the ring-necked pheasant (Phasianus colchicus L.) across the intensively managed agricultural landscape of the Czech Republic. The study area is influenced only marginally by hand-reared pheasants (i.e. as shown by comparison of the average number of released individuals in the study area: 0.3 ♂/yr/1km2 and 0.9 ♀/yr/1km2 and average number of released individuals and harvested in the study area: 8.6 ♂/yr/1km2) and there is a long-term huntable pheasant population. To determine the age of individuals, we used proximal primary feather shaft diameters of 1487 feather samples from males hunted between 2009 and 2011. Moreover, we evaluated the age structure of females as well as both sexes together based on the sex ratio and annual game census. We found a relatively high proportion of adults in the population in comparison with other studies. However, the number of adults decreased throughout the years: 2009 (♂ 44.7%; ♀ 69.5%; ♂♀ 60.7%), 2010 (♂ 35.2%; ♀ 61.3%; ♂♀ 51.5%), 2011 (♂ 29.8%; ♀ 57.4%; ♂♀ 47.0%). The decrease of adults went hand in hand with increase of juveniles and reproduction rates of the study population: 2009 (♂ 124%; ♀ 44%; ♂♀ 65%), 2010 (♂ 184%; ♀ 63%; ♂♀ 94%), 2011 (♂ 236%; ♀ 74%; ♂♀ 113%). Only males were hunted in the study area so we determined higher proportions of females in population for all years. This is the main reason why the reproduction rate of females was lower in percentage expression. Generally, our results showed lower productivity of pheasants in the Czech agricultural landscape in comparison with earlier published studies conducted in the US and UK. However, these studies were published many years ago and thus do not reflect the actual environmental conditions and changes which took place recently (i.e. agricultural intensification).
The variability of metric characters of 7 examined species to the biting lice, typical for the pheasants, totalled 2-6% for imagines. In some species the coefficients of variability for the measurements of thorax and abdomen reached value of 10%. As a rule, the head dimensions as well as the total lenght of three species had the lowest (to 3%) variability. The nymphs were characterized by the higher coefficients of variability of all examined characters, though also the lowest (3-8%) values were noted for the head dimensions whereas the highest (to 19%) ones for abdomen width. Such high values are probably associated with extending of the abdomen which is slightly sclerotized in the nymphs.
The tendency to roost overnight was studied in 91 juvenile "black-necked" and "ring-necked" Pheasants reared either under "semi-natural" or "commercial" pheasantry conditions. The birds were kept in cages in 4 different groups. Observations were carried out in 50 evenings. Numbers of individuals roosted per group were determined usually at four counts per evening in intervals of 10min., with the last count immediately before darkness. Data on weather parameters were recorded in each evening. All statistical tests were performed using arc-sine-transformed proportion values of roosted birds. The Pheasants started night-roosting at an age of 40-50 days. Roosting activity began approx. 40 min. before darkness and locomotory activity ceased right before darkness. Among the 4 rearing-groups considered, the tendency towards night-roosting was highest (median = 63.5%) in "black-necks" reared under "semi-natural" conditions and lowest (median = 35.0%) in "ring-necks" reared under commercial pheasantry conditions. Rainfall lowered the tendency from a median of 43% to 35%.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.