In the contemporary world environmental changes are effecting all spices not only a mankind. The negative phenomenon can lead to the dying out of beautiful animals, insects and so on. In order to prevent this it is necessary to spot a decline and identify its main causes in time. Of course, ecosystems are complex and there could be several negative factors. Even if not all of them could be controlled, it is essential to take all possible precautions.
Introduction
Monarch butterfly (Danaus plexippus) are colored black-orange-and-white. (Monarch Butterfly n.d.)They are the only mass migrating butterflies in North America. The migration brings millions of them to California and Mexico. Their journey started each fall can be as long as 3,000 miles and is induced by the death threat coming from the autumnal- winter fell of temperature.
Monarch butterflies lay eggs only on milkweed plant, which eggshells later serve larvae as nutrition. This chain of reproduction and breading makes Monarchs dependent on milkweed plants. As larvaegrowth they turn into caterpillars, who later enter the pupa stage after creating a hard protective case. Adults emerging from it have the distinctive protective pattern warning predators of disgust and poisoning.
The time of birth effect butterflies, because the emerged late summer and early fall are to fly a one round trip. The returning generation will their grandchildren. It is noticeable that even been new to the place they not only know the way, and follow the ancestor’s routes, but sometimes even returning to the same tree. (Monarch Butterfly n.a.)
Hypothesis for Monarch Butterfly Decline
Through the las years the total population of Monarch butterflies has declined, the literature review has shown that the main causes of this phenomenon are weather conditions, loss of habitat in the summer breeding grounds and decline in milkweed.
These three things represents need in living space, nutrition and normal living conditions.
The changes in weather conditions are common and their influence is understandable, as all living creatures have their own optimal living conditions. Any violations can lead to living condition deterioration, what int turn possibly leads to a decrease in population. This would not be that bad if only it was the only negative factor and the population could restore it number within next years.
The last factor named decline in milkweed was chosen as these plants are absolutely necessary for reproduction due to the monarch’s exceptionally selectivity in the choice of place for eggs laying-out and a food source for caterpillars.
Three decline factors: literature review
Weather conditions
This factor is the most obvious one as any living organism has its own comfort temperature, humidity intervals and can day out if exposed to the extreme conditions. It can also effect flora. Vidal and Rendon-Salinas (2015) have presented summarized weather effect data effect. They declared mass mortalities in the overwintering sites due to the severe rains and even snow and low temperatures. For example, authors cited Culotta’s research paper presenting that in 1992 extreme cold winter caused 83 percent reduction in the San Mateo Almomoloa colony butterflies population.
The close look on the weather conditions (Why the Decline 2015) favorability for monarchs shows that dough in 2012 caused their population decline, especially in the U.S. Corn Belt, where half of the migrating monarchs are born. Spring 2013 was characterized by low temperatures, thus the first spring generation after migration was developing slower. The slow start proceeded with unproductive summer breeding. In 2014 the weather conditions have changed and were ideal for Monarchs, but the population was still dangerously low in 2015, its total number was only 20% of the historic average of 300 million, and less than 7% of the maximal peak.
Habitat decline
The negative environmental conditions have been effecting not only the butterflies themselves, but also nature in general. The forest have been also effect by floods, fires and parasitic plants, what mad them less or even fully suitable for living. (Vidal 2015)
Though the reservations have been established (Catalan 2015), bust still people are performing illegal deforestation, what is especially dangerous for the colonies outside the reservation borders.
Milkweed plants decline
U.S. farmer’s extensive usage of herbicides destroys these plants and endangers the ecosystems. Smith (2014) presented readers with stunning data: in 2013 total milkweed plants amount on the USA territory has been only 79% of the number quoted in 1995. This means that less butterflies are presented with possibility for successful reproduction.
According to the research performed by Flockhar’s group in Ontario, who focused on relative comparison of potential threat effect on Monarch butterflies, the loss of milkweed has had the greatest impact on recent monarch declines. (Smith 2015) It is especially true for the future, as after several years the weather has become favorable and the government has acknowledged the problem and assessed the butterfly for inclusion on the USA endangered species list. (Save the monarch, 2015)
Conclusions
As it was shown the only Not American distant migrating butterfly population is endanger. It has declined through the las years due to the weather, nutrition and place factors. The research works shows clear evidence that the inclement weather conditions have caused three lowering of overwintering populations within the las decade. This negative situation has become worse due to the habitat takeover (often illegal) and decrease in the number and area of milkweed plants fields, which are mandatory for the eggs lying and
This simultaneous negative process development lead to the nearly 10-fold Monarch butterfly west population decrease from 1997 to 2010.
In order to halt it the activist are calling not only for conservation actions and help from state (Reserve establishment), but for public help (milkweed plants growing in the gardens). This problem has become national and this insect was
Referances
‘Save the monarch’, 2015,New Scientist, vol. 225, no. 3003, p. 7. Available from: < http://www.sciencedirect.com/science/article/pii/S0262407915600501>. [17 February 2016].
Monarch Butterfly Danaus plexippus, n.d. Available from: <http://animals.nationalgeographic.com/animals/bugs/monarch-butterfly/> [February 17 2016]
Rees Catalan, AK 2015, ‘The Monarch Butterfly Biosphere Reserve: An exemplary participative approach?’, Environmental Development, vol. 16, pp. 90-103. Available from: < http://www.sciencedirect.com/science/article/pii/S2211464515000354>. [17 February 2016].
Smith, LN Monarch Butterfly's Reign Threatened by Milkweed Decline, 2014. Available from: <http://news.nationalgeographic.com/news/2014/08/140819-monarch-butterfly-milkweed-environment-ecology-science/> [February 17 2016]
Vidal, O & Rendón-Salinas, E 2014, ‘Dynamics and trends of overwintering colonies of the monarch butterfly in Mexico’, Biological Conservation, vol. 180, pp. 165-175. Available from: < http://www.sciencedirect.com/science/article/pii/S0006320714003589>. [17 February 2016].
Why the Decline?, 2015. Available from: <https://www.learner.org/jnorth/tm/monarch/conservation_overview.html> [February 17 2016]
