New Zealand wrens are suspected to have the ability to hibernate

Rocky new Zealand Wren (Xenicus gilviventris), presumably, can hibernate, reported in the Journal of Experimental Biology. This preliminary conclusion biologists have made estimates of the extent to which changes the intensity of the metabolism of birds, and to compare it with data on the diet of the Wren and the climate in its habitat. To finally clarify the question, we need to know how long can numbness X. gilviventris. If the researchers are correct, rocky the winter Wren will be the second bird in addition to the American rock Nightjar, which has a winter hibernation.

Birds have a metabolism almost always very intense: otherwise it would be difficult and even impossible to ensure the flight. But the climate in most parts of the globe that birds can’t feed in one place all year round. So they have at certain seasons to migrate to areas where food remains available. These birds differ from mammals and some reptiles, capable of winter or a very hot and dry summers slow down the metabolism and enter a dormant state.

A number of hummingbirds and other birds under adverse conditions, flows into a short daze (torpor). While they have reduced body temperature and metabolic rate. In a daze they can survive the lack of food, cold of the night and other troubles that do not last more than several days. Longer a state of torpor, from which an animal may occasionally go out for a bit, called hibernation (if it occurs in winter; also called winter) or activatea (if it is observed during the summer). But hibernate can only one bird is an American rock Nightjar (Phalaenoptilus nuttallii). Research under controlled conditions has shownthat he can hold in a state of stupor for up to 45 days.

Brian McNab (Brian McNab) from the University of Florida and Kerry Weston (Kerry Weston) from the Ministry of environmental protection of New Zealand suggested that the hibernate can not only American nightjars, but the rocky new Zealand wrens. These birds are no larger than 10 centimeters have very distant relatives of the American wrens (Troglodytidae) and belong to another family or even suborder (Acanthisittidae) passerine.

The assumption of the Wren rocky hibernation, scientists have made based on several factors. First, its close relative, Rifleman (Acanthisitta chloris) easily falls into a stupor. Second, rocky wrens eat insects and live in open areas at altitudes from 1000 to 2900 meters. In the winter it can drop several feet of snow, so insects this time of year birds can’t catch. However, they did not go down to the woods, when it gets cold.

Rocky new Zealand Wren — a very rare bird, and in practice its ability to fall into a daze not previously studied. The authors of the article caught six birds of this species in winter 2016 in Fiordland national Park. Wrens were put in a room, the temperature in which was changed from 5 to 31 degrees Celsius, and measured the amount consumed by the birds of the oxygen, and the temperature of their body at different times. This allowed the researchers to calculate the metabolic rate of animals.

Normal body temperature alone for small passerines of temperate climate — 39-42 degrees Celsius. However, rock wrens, it was only 36-37 degrees. Lower the room temperature to +9.4 body temperature of one of the wrens fell to +33,1, and when heated the air in the room to +30,1 independently recovered to normal for a bird. Metabolic rate in two birds in the cold in the room decreased by 30-35 percent, almost to a level as if they were cold-blooded.

Such instability in body temperature and metabolic rate X. gilviventris suggests that they could fall into a daze and probably in hibernation. The authors mentioned several times that rock wrens observed torpor, but did not give references to these observations and do not indicate expressly that in the course of their study, this condition has occurred. They also write that to determine whether rocky, the new Zealand wrens can hibernate, you need to determine what is the maximum time (how many days) they spend in a state of torpor. Such data yet, but probably will be able to in the future.

Those animals which have winter sleep is confirmed by observations and experiments, for a period of “awakening” can influence the ambient temperature, the concentration of testosterone and other hormones and probably even some unaccounted factors. That could happen with the animals, experiencing the cold with slow metabolism, this abnormally warm winter in Central, we predicted the material “Scumbags.”

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