Spain’s two pelagic destinations operate on the same broad summer-to-autumn window but on genuinely different biological timelines. The Gulf of Cádiz — where the Birding the Strait trips depart from Chipiona in Cádiz Province — runs a four-month season from July through October, centred on the post-breeding dispersal of the Critically Endangered Balearic Shearwater and the autumn trans-Atlantic skua migration. Nine hundred kilometres south in the subtropical Atlantic, Lanzarote Pelagics offers just two overnight departures per year to Banco de la Concepción in August and September — a narrow window that coincides with the activity peak for White-faced Storm-Petrel, Band-rumped Storm-Petrel, and the Canary Islands’ extraordinary Macaronesian seabird community.
Getting the timing right matters for both destinations, and the decision between sites — or the practicality of combining them — depends heavily on which species you are prioritising.
Gulf of Cádiz: July to October
The Gulf of Cádiz pelagic season is anchored by one defining species: the Balearic Shearwater. With a global population estimated at fewer than 20,000 birds — all breeding exclusively on the Balearic Islands in the western Mediterranean — every individual passes through or near the Strait of Gibraltar during post-breeding dispersal from late June onwards. The shelf-break waters 15–18 nautical miles offshore from Chipiona are consistently documented as one of the most important post-breeding foraging areas for the species in the world. The Gulf of Cádiz Pelagic run by Birding the Strait reaches this shelf edge in approximately 2–2.5 hours, spending the productive mid-trip hours chumming with up to 40 kilograms of fish oil and offal.
July
The season opens in July as the first Balearic Shearwaters arrive from the Mediterranean. Numbers build through the month; early July trips typically produce a few dozen individuals, late July trips regularly reach triple figures. Cory’s Shearwater — including both nominate Atlantic Cory’s and the closely related Scopoli’s Shearwater — is already numerous, with dozens to hundreds banking low over the Atlantic swells throughout the trip. Great Shearwater, the trans-equatorial migrant from Tristan da Cunha that peaks in North Atlantic waters from July into August, is reliably present in good numbers. Sooty Shearwater, passing through on its own circum-Atlantic migration from Tierra del Fuego and the sub-Antarctic, adds a third large shearwater species.
Wilson’s Storm-Petrel is present from July, a tiny bouncing tubenose that performs its characteristic foot-pattering feeding behaviour around the chum slick. The first skuas of the season begin to appear in late July: primarily Great Skua, approaching the vessel to investigate the chum.
August: Peak Season for Shearwaters
August is the prime month for peak shearwater diversity and raw numbers. Balearic Shearwater concentrations are at their highest, with multiple hundreds of individuals on productive trips and counts into the thousands on optimal days. The combination of Balearic, Cory’s/Scopoli’s, Great, and Sooty Shearwaters simultaneously gives the Gulf of Cádiz one of the richest shearwater assemblages accessible from any European departure port.
Storm-petrel diversity peaks in August and September. Both Wilson’s Storm-Petrel and European Storm-Petrel attend the chum slick — the latter breeding on rocky Atlantic islands and appearing alongside Wilson’s in a side-by-side comparison that is extremely difficult to achieve in any other European setting. Individual birds linger around the stern rather than flying briefly past, enabling prolonged study.
The skua migration is building in August. Great Skua is present. Pomarine Skua begins to appear in increasing numbers as the month progresses. Sabine’s Gull, the delicate Arctic-breeding gull that migrates offshore along the eastern Atlantic on a precise schedule, appears in August — adults first, with juveniles and September counts generally higher. Audouin’s Gull, the Mediterranean endemic restricted to approximately 22,000 pairs globally, appears regularly from its Spanish breeding colonies.
September: Peak Season for Skuas
September shifts the balance toward the autumn passage. Balearic Shearwater numbers remain high into mid-September. More importantly, all four North Atlantic skua species are now on the move: Great Skua, Pomarine Skua (peaking September–October), Arctic Skua (August through October), and in smaller numbers Long-tailed Skua. The interaction between kleptoparasitic skuas and the attending shearwater flocks — twisting aerial pursuits over the chum slick — is one of the defining spectacles of a Gulf of Cádiz trip, and September offers the broadest overlap of skua species.
Sabine’s Gull is at its most numerous in September. Storm-petrel variety continues with Wilson’s and European Storm-Petrel; the first Leach’s Storm-Petrel of the season can appear from September onward, though numbers are lower than at more northerly Atlantic sites.
October
October extends the season with a shift in composition. Balearic Shearwater numbers decline through the month as birds continue south. Compensating for this, October is the best Gulf of Cádiz month for Long-tailed Skua — the graceful pale skua with elongated central tail feathers that reaches peak passage concentration in October as it heads south from Arctic breeding grounds. Pomarine Skua passage intensifies. Grey Phalarope, the compact bobbing wader that winters at sea, begins to appear in late October. Leach’s Storm-Petrel numbers peak in October.
The season ends in late October as shearwater passage dwindles and weather conditions become more variable.
Canary Islands: August and September
The Canary Islands pelagic season operates on an entirely different schedule. The Banco de la Concepción Pelagic run by Lanzarote Pelagics is an overnight expedition to the submarine seamount north of Lanzarote, where deep Atlantic water rises to within 150 metres of the surface, driving a permanent upwelling that concentrates seabirds in extraordinary numbers. There are only two departures per year, both in August–September — this is not a season with flexible booking windows. Missing the departure means waiting a full year.
Why August–September
The timing aligns with three overlapping factors: the peak foraging activity of Macaronesian breeding storm-petrels, the northward post-breeding migration of Great Shearwater and trans-equatorial species, and the overnight conditions that make chumming for storm-petrels most productive. Unlike the Gulf of Cádiz day trips, participants sleep aboard in open Atlantic water and observe the seamount across the full nocturnal window, when storm-petrel activity is highest.
The signature target is the White-faced Storm-Petrel — a pale, long-legged tubenose with a distinctive white face and dark eye-mask that uses its extraordinary legs to patter and bound across the sea surface in a kangaroo-like flight style unlike any other storm-petrel. The White-faced Storm-Petrel breeds on Montaña Clara and Alegranza in the Chinijo Archipelago — the islets the trip departs near — and multiple individuals are recorded on most trips during the peak window. Six were observed on the September 2022 overnight departure.
Band-rumped Storm-Petrel — numerically the most reliable species at the seamount — is recorded in counts of 30 to 40 or more per night. The Chinijo Archipelago and Selvagem Islands host the most important North Atlantic colonies of this species, and the Banco de la Concepción lies within direct foraging range. Wilson’s Storm-Petrel attends in smaller numbers alongside European Storm-Petrel, creating the potential for a four-storm-petrel evening.
The seamount has produced Black-bellied Storm-Petrel on multiple occasions — including the first four Canary Islands records, all from these Lanzarote Pelagics trips between August and October. This sub-Antarctic vagrant surfaces only at precisely the right combination of offshore location, overnight hours, and chumming; the Banco de la Concepción is now the most reliable location in the eastern North Atlantic to search for it.
Cory’s Shearwater dominates the daylight hours numerically, with single-trip totals regularly reaching several thousand. Bulwer’s Petrel, the small all-dark tubenose breeding on the Canary Islands and Selvagens, is reliably encountered with 20 or more on a typical trip. Barolo Shearwater (the Macaronesian form) appears regularly; Great Shearwater adds trans-equatorial passage interest.
Long-tailed Skua is reliably recorded under optimal conditions; Pomarine Skua and South Polar Skua have both been recorded on these trips.
Late August vs. Early September
The two annual departures typically fall in late August and early to mid-September. Late August offers the strongest overlap with peak White-faced Storm-Petrel activity and the highest Barolo Shearwater numbers. Early September brings more Great Shearwaters and increases the probability of Black-bellied Storm-Petrel vagrancy; skua activity also increases slightly. Both windows are productive and the difference between them is marginal compared to the difference between going and not going.
Best Months by Target Species
| Species | Best Months | Location |
|---|---|---|
| Balearic Shearwater | August–September | Gulf of Cádiz |
| Cory’s / Scopoli’s Shearwater | July–October | Both |
| Great Shearwater | July–August | Gulf of Cádiz |
| Sooty Shearwater | July–September | Gulf of Cádiz |
| Barolo Shearwater | August–September | Canary Islands |
| Bulwer’s Petrel | August–September | Canary Islands |
| Wilson’s Storm-Petrel | July–September | Both |
| European Storm-Petrel | August–October | Gulf of Cádiz |
| White-faced Storm-Petrel | August–September | Canary Islands |
| Band-rumped Storm-Petrel | August–September | Canary Islands |
| Black-bellied Storm-Petrel (vagrant) | August–October | Canary Islands |
| Leach’s Storm-Petrel | September–October | Gulf of Cádiz |
| Great Skua | August–October | Gulf of Cádiz |
| Pomarine Skua | September–October | Gulf of Cádiz |
| Arctic Skua | August–October | Gulf of Cádiz |
| Long-tailed Skua | October | Gulf of Cádiz |
| Sabine’s Gull | August–September | Gulf of Cádiz |
| Grey Phalarope | October | Gulf of Cádiz |
| Audouin’s Gull | July–October | Gulf of Cádiz |
| South Polar Skua (vagrant) | August–September | Canary Islands |
Quick Reference: Which Site, Which Month?
July: Only the Gulf of Cádiz season is open. The early season emphasises Great and Sooty Shearwaters alongside building Balearic numbers. The Canary Islands expeditions do not run in July.
August: Both sites are active and near peak. The Gulf of Cádiz delivers the highest Balearic Shearwater counts of the season and the first significant skua movement. The Canary Islands overnight trip in late August offers White-faced Storm-Petrel, Band-rumped Storm-Petrel, and Cory’s Shearwater in the thousands.
September: Both sites remain productive. Gulf of Cádiz reaches peak skua diversity — all four species overlap — while Balearic Shearwater numbers remain solid into mid-September. The second Canary Islands departure falls in early September. Storm-petrel variety is at its highest at both sites.
October: Only the Gulf of Cádiz is running. October is the best month for Long-tailed Skua, Grey Phalarope, and Leach’s Storm-Petrel — species that reward end-of-season trips. The Canary Islands expeditions are finished for the year by October.
Can You Combine Both?
August is the single month when both destinations are simultaneously at or near peak productivity. Lanzarote Airport receives direct flights from London, Amsterdam, Frankfurt, and other northern European hubs; flights from mainland Spain (Seville, Jerez, Madrid) take under two hours. A combined Spain pelagic itinerary is feasible: travel to Chipiona or Cádiz for Gulf of Cádiz day trips in early August, then fly to Lanzarote for the late-August overnight Banco de la Concepción departure, returning to mainland Spain afterwards.
September offers a second combination window if the Canary Islands trip falls in early September: a September Gulf of Cádiz trip emphasising skua diversity, followed by the Lanzarote departure, gives breadth across the eastern Atlantic seabird assemblage in a single two-week trip.
The constraint is the availability of the Canary Islands departures: with only two per season and each filling months in advance, the Lanzarote departure date determines the itinerary rather than the other way around. Contact Juan Sagardía to confirm departure dates before booking mainland travel.
Practical Notes
Gulf of Cádiz access: Jerez de la Frontera Airport (XRY) is the closest airport to Chipiona, with connections from Madrid, Barcelona, and several European cities. Seville Airport (SVQ) is the primary international hub for Andalucía — Chipiona is approximately 1.5 hours by road. The Birding the Strait trips depart from Chipiona harbour.
Canary Islands access: Lanzarote Airport (ACE) receives direct flights from London, Amsterdam, Frankfurt, and across northern Europe. Participants take a public ferry from Órzola at the northern tip of Lanzarote to La Graciosa (approximately 25 minutes), the departure point for the overnight expedition. Allow one full buffer night on each end in Lanzarote for flight and ferry connections.
Booking lead times: Gulf of Cádiz trips are announced via the Birding the Strait newsletter at the start of each season — the minimum six-participant threshold means early registration affects whether a trip runs. Lanzarote Pelagics departures must be booked directly with Juan Sagardía and routinely fill months in advance; contact him as soon as the upcoming season’s dates are announced.
Seasickness: The Gulf of Cádiz shelf-break crossing is generally manageable, but the shelf edge can be rough in southwesterly conditions. The overnight Lanzarote trip involves extended open-ocean time and represents genuinely demanding sea conditions — come prepared with scopolamine patches or meclizine taken the night before. The nocturnal storm-petrel observation around the chum slick is the highlight of the Canary Islands trip; being incapacitated by seasickness for it would be a significant loss.
Optics: Quality binoculars pay dividends at both sites. At the Gulf of Cádiz, storm-petrel identification in Atlantic conditions rewards magnification and good low-light performance. On the overnight Lanzarote trip, storm-petrels approach the chum slick at close range after dark — bring a headtorch for viewing them at close quarters.
For the full guide to which trips are available and what to expect on each, see our Best Pelagic Birding Trips in Spain. Browse all listed Spain pelagic trips at the Spain directory.