According to a blog post on adgooroo.com, in the first four months of 2013.

“Paid search spend in the Travel category on U.S. AdWords is down in 2013.

At $238 million for the months of January through April, it’s actually down 19% from 2012’s $295 million during the same period, which was down 17% from 2011.

 

 
“Clearly, there’s a downward trend starting in 2011. And the trend holds throughout the summer months as well, with spend from May through August 2012 down 15% from the same period 2011. If the trend continues, then we estimate the spend this summer will total only $242 million, more than $100 million less than two years ago.”

 

“A more plausible explanation is that Google has been cannibalizing its advertisers’ clickthroughs and spend with their own travel marketing efforts. ”

“After all, the decline in PPC spend began in 2011, a year in which Google Flight Search and Google Hotel Finder launched (in September and August, respectively). ”

“It would not be a stretch to conclude that the presence of these new Google features in the first SERP results–the travel equivalent of their Product Listing Ads in that they display a provider AND a price–may be poaching large amounts of clickthrough traffic (and thus PPC spend) from the paid ads on the page”.

With the vast majority of travel bookings now taking place online, Travel is a highly competitive category for paid search. Based on PPC-generated impressions, the Top 10 paid search advertisers on U.S. AdWords in the Travel category in 2012 were:

 

1. kayak.com – 883 million impressions
2. priceline.com – 699 million impressions
3. orbitz.com – 670 million impressions
4. tripadvisor.com – 663 million impressions
5. cheapoair.com – 629 million impressions
6. expedia.com – 595 million impressions
7. booking.com – 538 million impressions
8. travelzoo.com – 469 million impressions
9. bookingbuddy.com – 353 million impressions
10. hotels.com – 349 million impressions

The following insights were derived from examining the Top 100 Most Clicked Keywords:

 

• The growing popularity of the keyword “vrbo” (vacation rental by owner), which rose to position 51 in 2013 from 78 in 2012, may indicate a new trend in consumer travel habits and a threat to the hotel business.
• Average clickthrough rate was 8.1%, with navigational terms posting much higher rates and generic terms yielding much lower clickthroughs (“flight” was lowest at 1.4%)
• Queries on “Airlines” yielded the most paid ads: 10.6 per SERP, while searches on “Greyhound” yielded less than 1, on average
• “Vacation packages” was the term with the most bidders, with 259 advertisers gaining first SERP impressions during the first quarter of the year. “Greyhound” had the fewest bidders (4).