FOR more than a year now, I have been watching peregrines in the unlikely setting of a chemical plant in Hull. Salt End Chemicals Park is a 370-acre industrial site on the banks of the Humber estuary. It consists of nothing but steel, steam and concrete. There’s barely a blade of grass in sight.

And yet, for a pair of peregrines, this is home. I first visited the site last year, at the invitation of Mike Sibley, a bird enthusiast and former shift supervisor at BP; one of eight companies based at the site.

Mike is also one of a team of people involved in protecting the peregrines there.

Before I was allowed in I had to put on thick fire-proof overalls, a hard hat, gloves, goggles, and steel toe capped boots.

Once on site, Mike pointed to a cooling tower high where I could just make out a “blip”. “That’s the female peregrine,” he told me.

I looked through my binoculars. She was perched on the site’s tallest structure, overlooking a jungle of towers and pipes and beyond to the Humber.

Mike led me to Vivergo Fuels, a bio-ethanol plant where staff had built the peregrines a nest box. Three newly-fledged peregrine chicks, two females and a male, were perched high on a grain silo.

Directly beneath the peregrines a procession of lorries unloaded wheat to be turned into biofuel. Steam belched from the towers.

I followed Mike up a metal stairway that scaled a 100ft-high milling building.

As we climbed Mike gestured to me to put my ear plugs in. We entered the building, past a wildly-gyrating sifting machine. The noise must be deafening for a bird.

We went up a ladder, climbed up a level and outside on to a walkway bridging the grain silos. Here I had a good view of the nest box. The male peregrine flew over our heads.

Later that year Mike invited me back to help clean and re-gravel the nest. I kept a sample of the feathers and bones from the nest box to analyse. My findings showed that, like most peregrines these industrial birds mainly hunted pigeons, but their diet was also enriched by woodcock, little grebes and quail picked off the Humber; a major route for migrating birds.

By April the peregrines were nesting again. I returned to see the female sitting on eggs through a one-way glass window at the back of the box. As I watched the male arrived and while they swapped places I glimpsed five dark-brown speckled eggs.

The chicks hatched shortly after this visit. Peregrine chicks can double their weight in just six days.

At three weeks old they were 10 times their weight at hatching. At 42 days these birds would be ready to fledge.

Before they fledged they were rung. Each chick had one British Trust for Ornithology ring clipped onto each leg. The first was a metal ring, ingrained with a unique identification number, the second a plastic Darvic ring, a wide orange band which can be read with binoculars. These would ensure the chicks can be traced back to Saltend.

Interestingly, the adult female wears a black Darvic ring, No: 42, which tells us she hatched from a nest on Chichester Cathedral. Interesting that this falcon had flown 200 miles to settle on a chemical plant.

As Paul Collins from Spurn Bird Observatory snapped the rings on, I looked out. The male peregrine was in full stoop, after a pigeon on the far side of the Vivergo site. I watched it swoop between the towers and disappear behind a plume of steam.

Then the female also took off and flew into a wood pigeon. As the pigeon plummeted to the ground, she plucked at its tail feathers. With five hungry chicks to feed there was real drama in the sky.

Then the female returned to the box, gripping its prey in its talons. The chicks called out hungrily. As it landed one chick rushed forward and grabbed the pigeon, dragging it to the back of the box where it stood guard over it, trying to hide it from its siblings.

I returned to Saltend in time to see a peregrine chick take its first, faltering flight.

Seeing the young falcon steady itself on the shifting air currents, I was overwhelmed at how this industrial plant’s conservation efforts had made a magical moment like this possible.