Let's organize everything we have learned so far about birds and group the various factors according to benefit and harm!

USEFUL BIRDS:
Our birds are irreplaceable predators: due to their high body temperature and the rapid decomposition process taking place in their bodies, their basic activity is continuous feeding. A tit can destroy up to 1,500 insect eggs per day, and the goldcrest, gray flycatcher and black redstart can feed their chicks up to five hundred times a day.
Our birds are effective weed controllers - just a few examples: finches live almost exclusively on weed seeds in autumn and winter, and the goldfinch and european greenfinch feed their chicks with weed seeds.
Excellent seed spreaders and pollinators: worldwide, they pollinate more than 1,500 cultivated plant species and 3-5% of medicinal species - three quarters of them are not capable of self-pollination.
Go back through the course material and recall why our birds are such important informants and why they play a key role in the ecosystem!
Birds are also guardians of our health: their consumption of fly larva is of particular public health importance, amounting to 72%. In addition, time spent in nature, observing birds, also has a positive effect on our health: research has proven that it helps to overcome stress, anxiety and depression.
HARMFUL BIRDS?
During their seed distribution, birds cannot choose between useful and dangerous species, so they play a role in the spread of invasive species. However, the extent of this is questionable, since it has been proven in many cases that not only birds, but also humans are responsible for the extinction.
The main argument against them is the crop damage they cause: the starling, for example, can damage the vines during its early autumn migration, but it protects the newly sown alfalfa from pests. Only a maximum of 10% of its diet is the fruit of the vineyards and orchards, the rest is made up of food of animal origin, so it also brings serious benefits to agriculture and forestry as well.
According to the comparative studies of the consumption of useful seeds and weed seeds, the Eurasian collared doves that go to the fields consume three times more weed seeds than useful seeds, and it was also proven that the majority of the consumed useful seeds were seeds unsuitable for cultivation.
Birds mainly eat insects on dead bees, not bees: swallows do not hunt bees, but flies and butterflies gathered on bee carcasses, and the tit looks for wax moth pupae in the cracks of hives. It is true that european bee-eater cause serious damage to apiaries, but this is significant in the case of migratory apiaries, and can be reduced to a minimum by carefully choosing the place of settlement.
A frequently arising problem is the question of excrement, which is also considered twofold: bird excrement, like the excrement of many other species, also functions as a natural fertilizer, but in a given place and under certain circumstances it is really a public health issue. And other disturbing factors, such as noise from birds or nesting in inappropriate places, the dirtiness of vehicles, are subjectively judged to be mostly the consequences of urbanization.
What is extremely important is the concept of NET EFFECTS!

Later, a research published in 2021, based on a global meta-analysis, also concluded that wild birds are an overall net benefit to agricultural production: they reduce crop damage and increase crop yields.
Read more:
Siefer P.D., Moya N.O., Fontúrbel F.E., Lavandero B., Pozi R.A és Celis-Diez J.L. 2021. Bird-mediated effects of pest control services on crop productivity: a global synthesis. Journal of Pest Science Volume 95/2022. p. 567–576.