The Effect of Ecological Factors on Cats’ Weight in Tehran

Some animals live in cities like humans. So, humans affect their life intentionally or unintentionally. Waste production is only one of the human effects on the urban ecosystem. The waste produced by human supply some of the food needed by urban cats. This research is the rst study in the world to measure the cats’ weight to investigate the effect of the increase or decrease in urban wastes on physical status of cats. In the rst phase of the research (Spring 2016-Winter 2017) in Tehran, we found that the average volume of the collected wastes had increased by 14% and it had led to a 1% increase in the average weight of cats in the mentioned period. The 9.5% decrease in the waste volume in Autumn 2016 had led to the decrease in the average weight of cats in Winter 2017. The male cats were more affected by the decrease in waste volume.


Abstract
Some animals live in cities like humans. So, humans affect their life intentionally or unintentionally.
Waste production is only one of the human effects on the urban ecosystem. The waste produced by human supply some of the food needed by urban cats. This research is the rst study in the world to measure the cats' weight to investigate the effect of the increase or decrease in urban wastes on physical status of cats. In the rst phase of the research (Spring 2016-Winter 2017) in Tehran, we found that the average volume of the collected wastes had increased by 14% and it had led to a 1% increase in the average weight of cats in the mentioned period. The 9.5% decrease in the waste volume in Autumn 2016 had led to the decrease in the average weight of cats in Winter 2017. The male cats were more affected by the decrease in waste volume.

Main Text
Urban people have created changes in their surrounding ecosystem that have affected the ecology of animals 1 2 . Cats (Felis catus) 3 are a group of animals living in cities and their life is affected by their coexistence with human. The economic and livelihood conditions of human societies significantly affect the content of trash bins. Although cats are hunters, trash bins are a source of food for them 4 5 6 7 . The effects of economic rises on human societies can be observed in trash bins. So, cats are also affected by these crises. For a better understanding of the extent of this effect, measuring the cats' weight is the best way to become aware of their ecological condition 8 9 10 . So, the raised question is: "What is the relationship between cat weight and the urban waste volume?" To answer the above question, the available papers were searched. However, no result was obtained. So, a project was designed to measure the weight of a group of cats in 13 regions of Tehran from Spring 2016 until Winter 2020. The research was done only on the cats that were older than 18 months. The criterion for determining the age of cats was their teeth. The research has been done in no country so far and so, it is considered a unique project.
In the first phase of the research (Spring 2016-Winter 2017), the weight of cats was measured in 13 regions of Tehran. In this period, 466 cats were weighted over four seasons. This population included 353 female cats and 113 male cats. In the spring, 112 cats were weighted including 84 female cats and 28 male cats. Also in summer, 112 cats were weighted including 84 female cats and 28 male cats. In autumn, 116 cats were weighted including 87 male cats and 29 female cats. In winter, 117 cats were weighted including 88 female cats and 28 male cats. After field studied and primary data collection in Tehran, the results of the first phase of the research were reported as presented in Table 1, Chart 1 11 , Chart 2, and Chart 3. The collected waste volume has increased by 14% in the period of Spring 2016-Winter 2017, and the average weight of cats has increased by about 1% in the same period. The average volume of collected waste during spring and summer was ascending and it was found regarding the increase in the weight of cats. It can be guessed that the average waste volume in Winter 2016 is almost similar to Spring 2016. According to the results reported in Table 1 and Chart 2, the average weight of cats in the period of Spring-Autumn 2016 was ascending. However, with the beginning of winter, this increase has stopped and even tended to reduce. This weight loss can be probably due to the beginning of winter and the decrease in the average volume of urban wastes during the autumn (Chart 1).
According to Table 1 and Chart 3, the average weight of female cats has had a constant increase, while weight loss has been observed in male cats during Summer and Winter. The weight loss of male cats during Summer may not be due to the waste volume. However, as mentioned above, the average weight of cats has decreased during winter with the decrease in waste volume. According to Chart 3, it can be found that the decrease of waste volume during autumn has mainly affected the male cats while causing a decrease in the weight growth flow in female cats.
It should be noted that regarding the biological properties of mammals 12 , the increase in the average waste volume in winter 2017 cannot lead to a sudden growth of the average weight of cats in spring 2017.
So, based on the observations, it is predicted that the average weight of cats increases to a limited extent in spring 2017. Meanwhile, there are two hypotheses about the reason for the increase in the average waste volume (about 14%). The first reason is the increase in waste production by citizens, and the second reason is that the waste accumulation systems of the municipality have become more efficient. In conclusion, it can be stated that the change in the average volume of the collected wastes has been effective in the average weight of cats.
It is suggested for other interested researchers to investigate the shares of hunting and waste in supplying the food needed by urban cats.