Population Dynamics of Avian Diversity in the District Okara, Pakistan

: Pakistan has a varied bird fauna, with over 790 species recorded and their distribution in three zoogeographical zones (Oriental, Palearctic, and Ethiopian), which is exceptional in the world. The data on avian diversity and abundance in the district Okara, Punjab was carried out from January 2022 to January 2023. Data were collected by direct, indirect, and flocks count methods on four transect points used in the study by visiting the field and by interviewing the local people and hunters about the current and past status of the avian fauna of the area. Okara district contains a major wetland for both local and international migratory birds, including falcons, gulls, plovers, snipes, waders


Introduction
Birds are among the most fascinating living creatures on the earth, Because of their naturally stunning feathers, enchanting melodies, and creative behavior, birds have always attracted humans [1].Any of the more than 10,906 extant species that are unique in possessing feathers are considered birds (class Aves) [2].Birds are particularly sensitive to environmental conditions and are utilized as bio indicators, so due to their great mobility, birds respond very quickly to changes in their surroundings [3].However, as a result of some harsh climatic conditions and many anthropogenic activities, bird diversity has been diminishing worldwide in recent years [4].According to Birdlife International (2015), 1375 bird species are endangered with extinction worldwide, with 84 species from the Indian subcontinent [4].
Pakistan has a varied bird fauna, with over 790 species recorded and their distribution in three zoogeographical zones (Oriental, Palearctic, and Ethiopian areas) is exceptional in the world [5].Thousands of birds migrate from various countries to Pakistan.There are seven fly zones in the globe, with one (Indus flyway) in Pakistan [6].The Indus flyway offers food and refuge for millions of migratory and resident birds [7].Okara is a district of Pakistan that is served by two rivers (Ravi river and Sutlej) and various canals are also found in this district [8].This area is wellknown for its rich plains, serene surroundings, and verdant fields of crops including potatoes, tomatoes, sugarcane, wheat, rice, and maize [9].Orchards for oranges and mangoes are prevalent.District Okara is a treasure trove for those who are interested in history, religion, and spirituality [10].
For a wide variety of birds, these habitats offer crucial wintering, staging, and breeding grounds [11].The variety and quantity of birds are influenced by environmental factors such as food availability, water quality, wintering areas, and breeding grounds [12].District Okara's land is an ideal environment for a variety of animals and plants, including birds, mammals, amphibians, fish, reptiles, and plants [13].The diversity and number of species are both important aspects of strengthening the environment.Evolutionary, historical, and environmental factors all contribute to patterns of bird diversity and composition [14].The assessment of bird communities has become an important tool in biodiversity conservation and in determining conservation actions for high-human-pressure areas [14].Monitoring the abundance of bird species, on the other hand, gives essential information that is frequently utilized in bird conservation and the management of vulnerable and endangered species [15].Furthermore, seasonal bird monitoring is critical for detecting variable bird migration in specific habitats [16].
The district Okara gives useful information on biodiversity and economic values.This data may be used to build regulations and conservation plans [17].Birds are great environmental indicators, assisting us in locating significant locations and providing a helpful measure of how effectively the country's ecosystems give advantages to humans [18].Thus, ornithological study and monitoring of district Okara biodiversity are critical ecological instruments that give vital information for sustainable ecosystems and climate change globally [19].Okara district is an industrial area so waste from industries pollutes the environment which affects the avian diversity [20].It is very important to protect the fauna of the Okara district of Pakistan, otherwise, the environment may deteriorate due to the negligence of the authorities of the Okara district [21].A major source of the degradation of the natural environment for bird species is the transition from rural to urban areas [22].Lack of vegetation and tree cutting allow pollution levels to increase, which affects the bird's diversity and other living creatures [23].Due to habitat destruction and human activity, bird diversity has been declining.This study was arranged to examine the species variety and the number of wild birds in the Okara district, Pakistan [24].No researcher has before investigated the avifauna of the district Okara.So the main focus of the study was to identify current bird diversity, major threats, and threatened bird species [25].This information on the species composition, variety, and richness of native and migratory birds is scarce.As a result, the current study is an attempt to investigate the current state and variety of the bird fauna in this area [26].

Study Area
In Pakistan's Punjab province, the district Okara has located between 30°48'4.968"North latitude and 73°26'54.0024"East longitude, at an elevation of 105 m. (344ft).The area of district Okara, Pakistan is 4,377 km sq (1,690 sq mi).The weather in Okara is often mild and dry.The coldest months are December through February when moderate rains and low temperatures can reach 3 °C (37 °F).May through July are the warmest months, with highs of up to 45 °C (113 °F).Before 1982, it was a part of Sahiwal District until becoming a distinct district.This district's name, "Okara," really derives from the word "Okan" (a lush green tree with needle-like leaves).The phrase Okanwala (Country of Okan), which eventually became Okara, was born from the tree Okan.Boundaries of the Okara District are shared with Bahawalnagar to the south, Pakpattan to the south-west, Sahiwal to the west, the Okara of Faisalabad and Nankana Sahib to the north, Kasur to the near-east and far-east, and Fazilka to the south-east (India).The Indian-Pakistani border's Radcliffe Line passes through the Okara District.The Sutlej River lies to the east, and the River Ravi is 100 kilometers to the west.With a total size of 6671 acres and high biodiversity, the Pipli Pahar forest is the most significant region in the Okara district.

Methods
The data on avian diversity was carried out from January 2022 to January 2023.Various field techniques were used at Four transect points throughout the survey [27].These techniques may be generally divided into two groups: 1) direct field observations and 2) indirect observations based on information from the locals.Point transect sampling was used to count and identify all birds heard and seen, as well as in flight [28].Four transect points were set to explore the diversity and abundance of birds (see Table 1).These transects' locations were chosen to include all types of habitats in this area (see the figure 1).The data collection was done from 6:30 am to 10:00 am (morning) and 5:00 pm to 7:30 pm (evening) from May-September and between 8:30 am to 11:00 am (morning) and 3:00 pm to 5:00 pm (evening) in October-April.Some survey was not conducted during poor weather or the rainy season [29].

Direct Count Method
This is the most diverse method used to measure species diversity and abundance.All the surveys were done on foot.Binoculars of Nikon, 30 × 100 were used to watch the birds [30].The coordinates of transects and the location of species were recorded using a GPS map.The bird's photos were captured using a camera Nikon D3400 (70-300 mm lens).Field guides were used to recognize the birds.With the use of field guides, the condition of resident, migratory, terrestrial, and aquatic birds was evaluated.

Flocks Count Method
The abundance was calculated using this method when the birds were gathered in big flocks.A block of birds within a flock was counted or evaluated by using this technique [31].Depending on the flock size, there were 15, 20, 25, 30, 50, or 100 birds in the flock.

Statistical Analysis
PAST version 2.17C software was used to assess diversity indices from all of the acquired fieldwork data of birds (Shannon, Simpson, Margalef, Dominance, and Evenness).
From January 2022 to January 2023, the maximum population was counted each month and transect.

Bird Monitoring Frequency
From January 2022 to January 2023, 113 surveys were completed to track the diversity and abundance of birds along four transects.The maximum number of surveys ( 14) was carried out in July, and the least number (6) in December.The four research sites were chosen to assess bird abundance; the highest number of surveys (56) were conducted at Transect Points 1 and 2, while the lowest number (31) was at Transect Point 4. The research sites were checked under the weekly plan.Because of the weather, certain surveys under the fieldwork plan were not carried out.

Discussion
The purpose of this research was to track the variety and number of birds in the district Okara, Pakistan.The major determinants of variance in the bird population may be somewhat more related to food availability, feeding, and habitats than any other threat [32].According to the results of our study, the richness and dispersion of the local bird fauna depend significantly on the availability of food and habitat.The vegetation of the study area was rich and the study area had a rich avian fauna due to dense vegetation.A total of 201 bird species from 54 families and 19 orders were identified as part of the current study.They comprised 1 year-round visitor, 1 year-round resident, 54 winter migratory species, 23 summer migrant species, 13 passage migrants, and 110 resident species.The research area's biodiversity monitoring offers useful data on species diversity, wetland conditions, and economic significance.Wetland conservation plans and policies may be created using this data [33].
The birds are actively hunted and caught in Pakistan, where they are native, which may be causing local populations to decline, but the condition of the species as a whole is thought to remain stable [34].There are seven fly zones worldwide, and Pakistan is home to one of them (the Indus fly zone).The birds travel via the Hindu Kush, the Sulaiman Mountains, and Karakorum before landing in Pakistan near the Indus River.In the host nation, migrating birds such as falcons, cranes, swans, ducks, flamingos, waders, and geese are significant.Hence, the migratory birds that were observed in our research region were Mallard, Gadwall, Eurasian wegion, Eurasian teal or common teal, Northern pintail, Northern shoveler, Indian spot-billed duck, Garganey, Indian whistling duck or lesser whistling teal, Greylag goose, Bar-headed goose, Red-crested pochard, Common pochard, Ferruginous pochard or white-eyed pochard, Common shelduck, Ruddy shelduck, Tufted duck, Cotton pygmy goose, Chestnut-bellied sandgrouse or common sandgrouse which were primary winter visitor.Common winter visitors to the district Okara, Pakistan are the Common Sandpiper, Common Greenshank, Wood Sandpiper, Green Sandpiper, and Marsh Sandpiper.Common redstarts were the regular and regional migrants.Red turtle dove, Common reed warbler, Eurasian golden oriole, Common redstart, Richard'pipit, Rock sparrow, Common house martin, Siberian stonechat, Asian barred owlet, Eurasian sparrowhawk, Hen harrier, Grey heron, Common swift, Red-necked falcon were the summer visitor.Resident species in our study were House crow, house sparrow, Jungle babbler, Eurasian tree sparrow, Jungle prinia, Common redstart, White-winged lark, Indian golden oriole, Streaked weaver, Ashy-crowned sparrow-lark, Common wood shrike, Blunt-winged warbler, Yellow-eyed babbler, Afghan babbler, Common babbler, Russet sparrow.
The Grey Francolin (Francolinus pondicerianus) is a bird that is frequently connected to the drier areas of the Indus plains.The Grey Francolin was widespread throughout our investigation.The year-round visitor of the study region is the rosy starling.Great grey shrike, Long-tailed bush warbler, Isabelline shrike, Common grasshopper warbler, Rufousbreasted accentor, Greater spotted eagle, Black shoulder kite, Little bittern, Black-crowned night heron, Black-tailed godwit were the passage migrants in the study area.

Conclusion
The data on bird diversity shows the remarkable range of avian species present throughout the research area.A total of 201 bird species from 54 families and 19 orders were identified.Nonetheless, the district Okara site's evaluation of bird population conditions and trends has the highest value for bird conservation.The results of this study show that bird abundance varied across land use categories.It was noticeable that increasing the intensity of land use affected bird diversity.Furthermore, the observation shows that vegetation played a significant effect on bird community diversity and density trends across land use categories.Birds play an important part in ecological balance, and their diversity reflects the variety of environments they inhabit.Yet, many specie's survival is challenged by many reasons such as habitat degradation, climate change pollution, and invasive species.As a result, we must take steps to conserve avian fauna by conserving and restoring their habitats, minimizing human-caused risks, managing invasive species, monitoring bird and educating communities.By following these actions, we can secure the survival of bird species and their variety for future generations.

Figure 1 .
Figure 1.Map showing location of district Okara, site and selected study sites for analyzing avian species.

Figure 2 .
Figure 2. Percentage composition of species occurring according to seasonal distribution status.

Figure 3 .
Figure 3. Passeriformes order shows the maximum number of families as compared to others.

Figure 4 .
Figure 4. Monthly average of avian population showing the maximum values at Transect Points 1 and 2 observed from January 2022 to January 2023.

Table 1 .
Details of transects selected to check the avian fauna of the district Okara site.

Table 2 .
Transect-wise diversity indices of avian species from January 2022 to January 2023.

Table 3 .
List of globally threatened species recorded from January 2022 to January 2023.

Table 4 .
List of birds of district Okara.