The feeding habits of magpies

Magpie is a familiar resident bird, which is widely distributed in all parts of China. It can live in its specific range all year round, with high regional adaptability and strong reproduction. However, magpies have a variety of eating habits, including agricultural and forestry pests and crops, so the advantages and disadvantages of magpies have always been the focus of academic discussion.

The forest farm in Beijiushui Scenic Area is located in Laoshan Scenic Area, Qingdao. Starting from Licun, Licang District, go east through Beilongkou to the north, and then through Beizhai and Wuyi Lane, you can reach Beijiushui Scenic Area. This area is rich in water and biological species, which is an ideal place for many universities to carry out field practice. The author was lucky enough to take the opportunity of field practice to carefully observe and study some magpies (about 300) in this area.

See the natural landscape here (figure 1). We chose fixed-point observation and patrol observation along the river valley (Figure 2), and studied the habits of magpies in this area by using the methods of data statistics and in-depth observation.

Here is some information about magpies:

Magpie Darkmouth Magpie pica (Figure 3)

Common names: flying barge bird, four magpies, dry magpies and crow magpies.

Order name: passeriformes

Family name: Ravidae.

It is about 45cm long, with black upper body feathers and blue-green luster, and a large white spot on each shoulder of the back. The abdomen is white. The tail is longer than half its body length. When it stops, it keeps moving, especially when flying. Build nests, lay eggs and raise offspring in trees. Omnivorous, staple food insects.

According to the stomach analysis of 46 adult birds and 9 young birds collected by teachers and students of Peking University Biology Department near Haidian, during the six months of 1-3 and 9- 165438+ 10, the proportion of plant food was the largest, and animal food was the majority from April to July. In terms of weight, among adult bird foods, plant foods account for 68%, of which crops account for 32%, animal foods account for 365,438+0%, and insects account for 65,438+065,438+0%. Among the young birds' food, animal food accounts for 82% and plant food accounts for 16%. Insects are the main animal foods, including COLEOPTERA beetles and ORTHOPTERA locust eggs. From this point of view, adult magpies are harmful to crops in crop areas, but during the breeding period, adult birds and young birds eat a lot of harmful insects. Therefore, the quality of magpies can only be determined according to specific regions and seasons. Magpie nesting activities began as early as the end of February, and both male and female birds took part in nesting work. Magpie nests are built on tall trees, and the outer layer of the nests is made of thick branches. The nest has a top cover and an entrance and an exit on the side. The inner layer of the nest is covered with mud, hemp, grass roots, hair and feathers. A nest lays 5-8 eggs. Eggs are light green with gray and brown spots on them. During the feeding period, it was observed that the parent birds returned to the nest to feed 168 times a day. Magpies are widely distributed in China and are very common resident birds.

From the above data, magpies eat almost the same amount of crops and insects in the field, but young magpies eat more insects and are beneficial birds. Similar data have been obtained in our observation, but in the mountains without food crops, magpies' feeding habits mostly shift from grains to wild berries, insects and mollusks. The following is our statistical information about magpie's feeding habits.

Regarding the predation of magpies, due to the humid climate in Beijiushui, the temperature in summer is 20-27 degrees Celsius, and there are more than a thousand species of arthropods, most of which are forest pests. As can be seen from the figure, nearly 50% of the food source is forest pests, which is nearly twice as high as the farmland area shown in the data. In the forest with magpies, the number of caterpillars is obviously reduced, and eating berries accounts for the vast majority of its plant-based diet, which is also conducive to the spread of tree species. It can be seen that stocking magpies in the mountains has high economic value.

The survival activities of magpies can not be separated from nests, and they have a strong family nature, which is also a common phenomenon of birds of the family Corvidae. But the magpie nest has special requirements for trees. The author counted 34 magpie nests in the study area (Figure 4), of which 1 is on the antenna tower, 1 is on Metasequoia glyptostroboides, 2 are on pine trees, and the remaining 30 nests are all on Sophora japonica and Pterocarya stenoptera, with a ratio of 3: 2 and a height of 25-40m, which are basically concentrated in 20 nests. The thin crown is conducive to taking off from the tree; Branches are three-pronged, which is good for nesting. Therefore, Pterocarya stenoptera and Sophora japonica are ideal nesting trees. We also counted the number of tree species in this area. As can be seen from the data, magpies prefer Pterocarya stenoptera and Sophora japonica. The trees closest to the valley are also these two kinds of trees (Figure 5). Magpie nests are mostly built in river valleys, which may be directly related to their foraging activities.

In addition, the vegetation in this area is mostly covered by artificial pine forests, including three small locust tree forests and one small artificial bamboo forest of about one acre.

From July 3 to 6, 2004, we observed and counted the activities of magpies from 5 am to 20 pm every day. The main statistical objects are the flight state, habitat and activity purpose at each time. The main data comes from two observation points, namely, the observation point of tourist area (Figure 6) and the observation point of Deyueqiao (Figure 7). The observation point in the tourist area has a high terrain overlooking the valley; The observation point of Deyue Bridge is close to the valley, so it is easier to observe the behavior of magpies in the valley. In addition, we patrolled the valley where magpies are active and got some detailed observations. After sorting out and analyzing, the data on July 4th is the most representative. The climatic conditions of the observation point on July 4th, 2004 are: sunny \ \ Temperature 22-3 1 Celsius.

The following is the specific data analysis of the day:

Flight data analysis

It is easy to see the flight changes in different time periods from the data, which is related to its habits.

The change of flying up and down is: the frequency is high at noon and at night, because the temperature is high at noon, magpies often bathe or drink water in the valley, and they fly down from the trees on the river bank or return to the branches; At night, it is because many magpies fly out from low places when they return to their nests. The low data in the morning and afternoon for a period of time may be because it has been hidden during this time.

Hiding in the locust forest or pine forest, rarely landing in the valley.

There are generally two reasons for parallel flight: one is high-altitude horizontal flight caused by long-distance flight migration, and the other is low-altitude horizontal migration between trees on both sides of the valley. The latter is generally a banter or "social" behavior. The high data in the morning and evening is due to the first reason, and it is mostly due to the second reason at noon. The low valley is mainly caused by hunting or playing in the valley.

In the author's records, hovering flight accounts for a small proportion in flight, and is generally combined with parallel or up-and-down flight. Our observation is that hovering flight is generally accompanied by many magpies chasing in the air or preying on butterfly moths in the air. Flying around, mostly hunting at noon and playing before returning to the nest at night.

● Analysis of flight start and end points

According to the local topography, the author makes a statistical analysis of the five starting and ending locations shown in the figure below. Judging from the data in the picture, most people walk through the Woods and river banks in the morning, especially when they just leave the nest, and most of them act in groups. From 8: 00 a.m. to 10 a.m., most of them forage in the grass in or near the river valley, so the flight activities are not frequent. 10 to 2 pm, there are 3-5 animals in the Woods on both sides of the valley, flying and chasing on the branches, so the proportion of "tree-tree, crossing the river" in the picture is large. The peak data of "Ground-Tree" in two time periods are all due to playing or staying in the valley and then flying into the bushes. Perhaps because of the abundant food, most magpies here rarely cross the road to fly to higher mountains, so "crossing the road" has always occupied a small share in the record.

● Statistical analysis of habitats

This statistic does not include magpies that gather in the upper canopy in the morning and evening. Let's discuss "clusters" below. Statistically, the data peak appears in the upper canopy in the morning and evening, which is suitable for high-altitude horizontal flight. This data change is basically consistent with nesting and homing in the morning and evening. Living in the middle of the tree crown can reflect its frolic and "gregarious" behavior in the jungle, and from the time of frequent occurrence, it is concentrated from 10 to 5 pm; The activities of magpies under the canopy are beneficial to dive into the valley, which is related to foraging and playing.

● Statistical analysis of related behaviors.

From the chart, we can clearly read the behavior changes in different time periods, which are basically consistent with the statistical results such as flight changes. However, when we investigated the changes when it returned to the nest, some problems appeared. Many magpies first cluster on a dead tree, fly back to the nest, and then fly out of the nest, which has to be puzzled, and the behavior of this process is extremely complicated, especially the "clustering" activity. The author intends to make a concrete analysis of this issue in the following.

After the above data analysis, we can summarize the magpie habits as follows:

Behavior Table of Magpies in Laoshan North Jiushui Area (July)

Main behavior of time period

Long-distance flight from 4: 30 to 5: 30, cluster and sing.

Long flight from 5: 30 to 7: 00, foraging.

7: 00- 10: 00, drinking water and foraging in the valley.

10: 00- 13: 30 in the hillside forest, avoid strong sunlight.

13: 30- 15: 30 drinking, foraging and playing in the valley.

15: 30- 16: 30 playing in the Woods on both sides of the valley.

16: 30- 18: 30 Cluster, Feilong, singing.

18: 30-20: 00 Go back to the nest or stay in the bamboo forest in groups.

20: 00-go to bed the next morning.

The author also observed and recorded the detailed behavior of magpies in the valley many times:

● Observation records of some strange behaviors

At about 2 pm on July 3, we saw from the scenic spot through the telescope that there were three feathered young birds playing on a rock near the Bird's Nest about 100 meters away. Suddenly, two adult birds flew in with worms in their mouths, and three young birds flew forward quickly. At first, we thought that the three young birds would snatch food from each other, but they opened their mouths and stretched their necks upward, waiting for the adult birds to fill their mouths with food, and then flew into the Woods together. According to related books, the breeding period of magpies in different regions is very different, but it can be inferred that these young magpies were born in February-March this year. Except for its short body length, it is not much different from adult birds, and has the ability of long-distance flight and predation (the author found that these three young birds caught insects in the forest in the later period of follow-up observation). From the point of view of most birds, young birds should leave the nest when they are full-fledged, and adult birds will leave them alone. Even if you take care of them, you should put down the food and let the young birds peck by themselves. The author feels a little strange about the eating behavior of these three birds. This behavior was also found in the valley, and the situation was even more puzzling: three magpies were foraging together in the valley. Magpie A caught a slug, and Magpie B came to grab it. Magpie A flew to a big stone with food in its mouth, and Magpie C suddenly flew over. At first, we thought that C was also here to grab food, but it turned out that the A magpie with the bug was filling C's mouth. Why on earth do magpies care so much about their adult children? At present, there is not much information, which may be because the small magpie has low predation skills and limited food. For future generations to survive better, "parents" will lend a helping hand until the little magpie really becomes a monk.

Magpie is a bird with strong family values. At about 3 pm on July 4, the author found a magpie eating apricots in the valley. After a few bites, it suddenly flew to the branch and called "Cha, Cha, Cha" three times. Soon, seven magpies flew in and shared a delicious meal. About 3: 15, several more magpies flew in. The magpie who found the food first rushed to the new magpie and fought. At this time, the foragers with it also stopped to resist the "foreign enemy" together until the invaders were driven to the high branches on the other side. This gives us an interesting family drama "Unity is Power". Magpies spend most of their time in small groups and should be in families. Generally 3-7, they feed, play and return to the nest together.

Magpies are usually thought to specialize in hunting grasshoppers, caterpillars and other land or arboreal insects. In fact, magpies are also masters of aerial predation. Magpie's body is very long, especially its tail, which is not conducive to tumbling or spinning in the air, but smart magpies make full use of the conditions of the forest and overcome their shortcomings when hunting in the air. On July 4th, we witnessed a magpie catching a fish in the air in the valley. The magpie first rushed to the stork from the branch, disappeared and then rushed to the trunk of a big tree. It spread its wings, swung its tail forward, put a cushion on it, pressed its paws on the trunk, kicked its legs, and quickly bounced off the trunk into the air. At this time, the fish stork was already in its mouth. Magpies overcome the shortage of updraft through the flexible activities of their legs in the bushes and skillfully adapt to life in the jungle.

Observation and Analysis of Magpie Cluster Phenomenon

Magpies have colony behavior, which mainly occurs at 4:30-5:00 in the morning and 4: 30-7: 30 in the evening (July) (Figure 7). The author recorded the behaviors observed on July 3rd and 5th as follows:

July 3rd/Weather: Sunny/Temperature: 27 degrees Celsius/Location: Open space at the intersection of two rivers (there is a dead tree and a poplar, opposite an artificial bamboo forest).

16: 25 Two flies from the dead tree on the other side.

16: 42 Here come three more, playing on the dead tree.

At 17: 00, there were about 25 birds, and they began to fly between poplar trees separated from dead branches by 15 meters.

17: 24, another ten or so birds flew out of the valley, about 40 of them were * * *, and the dead branches were silent.

17: 35 A total of 1 flies flew down from the mountain, all of which stood up and flew away about half.

17: 50 another batch of about 20.

18: 12 Two birds came from the valley, and about 10 birds flew away when they were all set up.

18: 25 another batch, probably 17.

18: 40 also flew away.

18: 56 About 15 only on dead trees.

19: 02 about 12 flew away.

19: 22 it's getting late, there are still six dead branches, and the magpie's singing is weakened.

19: 36 The last one flew away (end of recording)

July 5/Weather: Sunny/Temperature: 29 degrees Celsius/Location: Open space at the intersection of two rivers (there is a dead tree and a poplar, opposite an artificial bamboo forest).

17: 25 Only dead trees have 13.

17: 45 There is a constant song on the poplar, but there is no trace on the dead branches.

17: 52 No other movement, restore calm (this place is on the side of the road, vehicles are shuttling)

Two flies flew out of the poplar.

18: 00 There are about 8 birds flying from all directions on the dead branches.

18: 05, nearly 30 birds gathered (some chasing dead branches and insects, mostly playing in pairs).

18: 12 suddenly flew away.

18: 16 occasionally there are 2-3 dead branches, and it becomes quiet again.

18: 40 returns about 20.

There are about forty trees.

19: 10 is called "Cha, Cha" on the poplar.

19: 25 flies into the bamboo forest below in batches, and magpies crow in the bamboo forest.

19: 35 It's getting dark, the trees are crying sporadically, and the bamboo forest is crying loudly.

19: 50, it was completely dark and quiet, and there were occasional calls in the bamboo forest (end of observation)

The observation results of the two days are very different, and the only similarity is clustering. As for birds, many birds, such as sparrows and crows, have similar behaviors. For the reasons, many scholars express their opinions, and most of them prevaricate with "not yet clear". In the course of our observation these days, the situation of No.3 and No.4 is similar, and there is little difference between No.5, No.6 and No.7. As for why clusters form, I can't jump to conclusions, but we think it must have something to do with family life. This season, this year's young magpies have all grown up, and this cluster may be a routine "social contact" between the young birds leaving the nest and their parents. Judging from the record of No.3, the cluster seems to be waiting for a bird, which can better reflect this point. From the observation results of No.5, it seems that the cluster is a communication way of collective reunion, where young birds can seek mates or fight with other birds to prove their strength (inferred from the birds and insects holding branches on No.5). But the biggest difference between the two records is that almost all of them flew away around 8 pm on the 3 rd, while many of them stayed in the small bamboo forest on the 5 th. The author has a bold guess that the birds staying in the small bamboo forest should be birds leaving the nest. Of course, these birds inevitably have to show off and please the opposite sex, so some of them are grabbing branches or fighting with other birds. Flying magpies may be relatives of these birds. As can be seen from the above records, magpies are still active in families, and they are "affectionate". In the evening, parents may come to this dead tree after completing a day's activities with the birds, put them down and let them integrate into another big group, that is, let the birds spend the night in the bamboo forest, and the cluster in the morning happens to be the "home" that parents call back. As for the magpies that didn't stay in the bamboo forest on the 3rd and 4th, it may be because they stayed elsewhere (there were many magpies chirping in the pine forest on the 4th night), but this is only the author's speculation.

● The influence of human activities on the life of magpies.

In the observation, magpies show a strong ability to adapt to the environment. The garbage brought by human beings is a "nutritious meal" for magpies. Every morning, many magpies gather in the dustbin for food. Moreover, the telephone poles and TV towers brought by human beings have become good places for magpies to nest and stay. However, other human activities, such as the noise of cars and activities in river valleys, will disturb the daily life of magpies. We investigated in the valley on July 6th, and there were no magpies in the whole valley from 8:00- 13:00 due to the construction noise. It can be seen that human activities have also had a certain negative impact on magpies.

In a word, magpie is a kind of beneficial bird in the forest, which is of great significance to the protection of the forest. In Laoshan Beijiushui Forest Farm, they also defend this mountain forest like their close relatives, Grey Magpie (the introduction of Grey Magpie into Rizhao Mountain Forest has achieved good results). Therefore, the introduction of magpies in major forest farms should have a good effect on the protection of mountain forests.