I am trying to findout reason behind shifting of wildlife towards higher elevation, How assumption can be made with a record of single individual at unusual elevation ?
Dear Chirinjibi, probably you are pointing to recent records of Bengal tiger at 2500 m at Dadeldhura of Nepal. We cannot say, Bengal tiger are not specifically a lowland species on basis of information that we have as they have been recorded at even higher altitude. For example Late Yonzon sir recorded at elevation higher than 4100 m. Similar records have been made from Indian mountains.
Second, prior to 2013 even Chure areas were not explored properly to search for signs of tiger. All the mid land incidence of big cat conflict incidence were attributed to Common leopards without proper research.
For reason of records of tiger at higher elevation, there could be few plausible causes:
1. Tiger were present there from the distance past but they occured at low density. This factor combined with the elusive nature of tiger make encounter low.
2. The prey species in Nepali protected areas are reported to decline. This decline probably have resulted in increase in home range of tiger occupiying core habitat forcing the weaker ones towards the edges. And edge dwellers to higher elevations.
3. As midhill areas are experiencing decline in human population, thus have resulted in increase forest area and enhancement of habitat quality in midhills attracting tiger there.
This all are plausible causes. We need to conduct more research to answer those questions.
Chandramani Aryal Not only Tiger at Dadeldhura, other lowland species are also recorded at unusual habitat.
Altitudinal migration generally occurs in species in response to climate change, food availability or anthropogenic effects. Species usually move to higher elevations when temperature rises or to escape from predators. Such movements can occur both during the reproductive and non reproductive seasons of the species. It is seen mostly in birds but can also be seen in other vertebrates and some invertebrates as well.
I think that Munira Nasiruddin is correct. That answer is logical and matches my opinions well, though I doubt that climate change plays too much of a role.
Avery Forrest III
We notice the same for some bird species here in Norway - too. My thoughts here is that it is related to warmer climate - but reasons for how it works can probabaly be complicated
Hello Chiranjeevi,
Munira provides some solid insights to your question that agree with my own, and Cooper provides some excellent resources for review. However, it is difficult to make broad scientific assessments based upon a single instance of a species being out-of-range or in non-typical habitat. For example, it's possible that the individual in question migrated off-course or was blown in by a storm front which would be entirely random; such occurrences happen frequently with avifauna. Rather, a trend in a species' or population's movement(s) over time is more explanatory. It would be a good idea to document the discovery of the species at the new elevation/location, and then monitor over time for any increase or decrease in observations at that location. Those observations could then be statistically tested along with other factors (e.g., temperature and weather changes, degree of habitat alteration, human interference, etc) for stronger conclusions.
It is a process of silent evolution and adaption that a species will increase its tolerance for lower temperatures. Drivers can be food unavailability and anthropogenic disturbance. Climate change can also increase lower temperatures at higher altitudes which will make it easier for species colonization. But other important factors include time and season, that is, whether the species is a temporary or a permanent resident. Seasonal opportunities for the species must also be studied, whether the prey or the fodder plants have also moved to higher altitudes and adapted. Lastly you have to study the size of the population in order to conclude that the species has moved in and bred successfully at the new geographical area.
Hi.
I agree with some views exposed here about the role of temperature and climate change in such recent changes in distribution and movements of many species. There are good examples of it in Spain; see this link:
https://www.miteco.gob.es/es/cambio-climatico/temas/impactos-vulnerabilidad-y-adaptacion/evaluacion_preliminar_impactos_completo_2_tcm30-178491.pdf
(The report is in Spanish but contains a lot of information on the subject).
Best regards.
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